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11 Commits
Author | SHA1 | Date | |
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d149c34307 | |||
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d9e55c7c81 | |||
c234ee7207 | |||
c6aae59407 | |||
e3f8ef00ae | |||
74481a0267 | |||
325b68908e | |||
694a1eeafa | |||
1496a468c5 | |||
af77911a84 |
18
.travis.yml
18
.travis.yml
@ -1,18 +1,20 @@
|
||||
language: java
|
||||
|
||||
jdk:
|
||||
- oraclejdk8
|
||||
- oraclejdk8
|
||||
|
||||
env:
|
||||
global:
|
||||
- GH_REF: github.com/iluwatar/java-design-patterns.git
|
||||
- secure: LxTDuNS/rBWIvKkaEqr79ImZAe48mCdoYCF41coxNXgNoippo4GIBArknqtv+XvdkiuRZ1yGyj6pn8GU33c/yn+krddTUkVCwTbVatbalW5jhQjDbHYym/JcxaK9ZS/3JTeGcWrBgiPqHEEDhCf26vPZsXoMSeVCEORVKTp1BSg=
|
||||
|
||||
- secure: "LxTDuNS/rBWIvKkaEqr79ImZAe48mCdoYCF41coxNXgNoippo4GIBArknqtv+XvdkiuRZ1yGyj6pn8GU33c/yn+krddTUkVCwTbVatbalW5jhQjDbHYym/JcxaK9ZS/3JTeGcWrBgiPqHEEDhCf26vPZsXoMSeVCEORVKTp1BSg="
|
||||
|
||||
before_install:
|
||||
- export DISPLAY=:99.0
|
||||
- sh -e /etc/init.d/xvfb start
|
||||
|
||||
- "export DISPLAY=:99.0"
|
||||
- "sh -e /etc/init.d/xvfb start"
|
||||
|
||||
after_success:
|
||||
- mvn clean test jacoco:report coveralls:report
|
||||
- bash update-ghpages.sh
|
||||
- mvn clean test jacoco:report coveralls:report
|
||||
- bash update-ghpages.sh
|
||||
|
||||
# Migration to container-based infrastructure
|
||||
sudo: false
|
||||
|
@ -1,13 +0,0 @@
|
||||
# Code Coverage Report generation
|
||||
|
||||
To generate the code coverage report, execute the following command:
|
||||
> mvn clean verify
|
||||
|
||||
This will generate code coverage report in each of the modules. In order to view the same, open the following file in your browser.
|
||||
> target/site/jacoco/index.html
|
||||
|
||||
Please note that the above folder is created under each of the modules. For example:
|
||||
* adapter/target/site/jacoco/index.html
|
||||
* busniess-delegate/target/site/jacoco/index.html
|
||||
|
||||
|
14
README.md
14
README.md
@ -23,16 +23,10 @@ are familiar with the patterns.
|
||||
|
||||
# Getting started
|
||||
|
||||
Before you dive into the material, you should be familiar with various
|
||||
[Programming/Software Design Principles](http://webpro.github.io/programming-principles/).
|
||||
Before you dive into the material, you should be familiar with various
|
||||
[Programming/Software Design Principles](http://webpro.github.io/programming-principles/).
|
||||
|
||||
All designs should be as simple as possible. You should start with KISS, YAGNI,
|
||||
and Do The Simplest Thing That Could Possibly Work principles. Complexity and
|
||||
patterns should only be introduced when they are needed for practical
|
||||
extensibility.
|
||||
|
||||
Once you are familiar with these concepts you can start drilling down into
|
||||
patterns by any of the following approaches
|
||||
Once you are familiar with these concepts you can start drilling down into patterns by any of the following approaches
|
||||
|
||||
- Using difficulty tags, `Difficulty-Beginner`, `Difficulty-Intermediate` & `Difficulty-Expert`.
|
||||
- Using pattern categories, `Creational`, `Behavioral` and others.
|
||||
@ -44,6 +38,7 @@ If you are willing to contribute to the project you will find the relevant infor
|
||||
|
||||
# Credits
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
* [Effective Java (2nd Edition)](http://www.amazon.com/Effective-Java-Edition-Joshua-Bloch/dp/0321356683)
|
||||
* [Java Generics and Collections](http://www.amazon.com/Java-Generics-Collections-Maurice-Naftalin/dp/0596527756/)
|
||||
* [Let's Modify the Objects-First Approach into Design-Patterns-First](http://edu.pecinovsky.cz/papers/2006_ITiCSE_Design_Patterns_First.pdf)
|
||||
@ -53,6 +48,7 @@ If you are willing to contribute to the project you will find the relevant infor
|
||||
* [Patterns of Enterprise Application Architecture](http://www.amazon.com/Patterns-Enterprise-Application-Architecture-Martin/dp/0321127420)
|
||||
* [Spring Data](http://www.amazon.com/Spring-Data-Mark-Pollack/dp/1449323952/ref=sr_1_1)
|
||||
* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)
|
||||
* [Pattern Oriented Software Architecture Vol I-V](http://www.amazon.com/Pattern-Oriented-Software-Architecture-Volume-Patterns/dp/0471958697)
|
||||
|
||||
# License
|
||||
|
||||
|
@ -4,13 +4,9 @@ title: Abstract Factory
|
||||
folder: abstract-factory
|
||||
permalink: /patterns/abstract-factory/
|
||||
categories: Creational
|
||||
tags:
|
||||
- Java
|
||||
- Gang Of Four
|
||||
tags: Java
|
||||
---
|
||||
|
||||
**Also known as:** Kit
|
||||
|
||||
**Intent:** Provide an interface for creating families of related or dependent
|
||||
objects without specifying their concrete classes.
|
||||
|
||||
@ -26,7 +22,3 @@ objects without specifying their concrete classes.
|
||||
**Real world examples:**
|
||||
|
||||
* [javax.xml.parsers.DocumentBuilderFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/parsers/DocumentBuilderFactory.html)
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>abstract-factory</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>abstract-factory</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -3,108 +3,71 @@ package com.iluwatar.abstractfactory;
|
||||
|
||||
/**
|
||||
*
|
||||
* The Abstract Factory pattern provides a way to encapsulate a group of individual factories that
|
||||
* have a common theme without specifying their concrete classes. In normal usage, the client
|
||||
* software creates a concrete implementation of the abstract factory and then uses the generic
|
||||
* interface of the factory to create the concrete objects that are part of the theme. The client
|
||||
* does not know (or care) which concrete objects it gets from each of these internal factories,
|
||||
* since it uses only the generic interfaces of their products. This pattern separates the details
|
||||
* of implementation of a set of objects from their general usage and relies on object composition,
|
||||
* as object creation is implemented in methods exposed in the factory interface.
|
||||
* The essence of the Abstract Factory pattern is a factory interface
|
||||
* ({@link KingdomFactory}) and its implementations ({@link ElfKingdomFactory},
|
||||
* {@link OrcKingdomFactory}).
|
||||
* <p>
|
||||
* The essence of the Abstract Factory pattern is a factory interface ({@link KingdomFactory}) and
|
||||
* its implementations ({@link ElfKingdomFactory}, {@link OrcKingdomFactory}). The example uses both
|
||||
* concrete implementations to create a king, a castle and an army.
|
||||
* The example uses both concrete implementations to create a king, a castle and
|
||||
* an army.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
private King king;
|
||||
private Castle castle;
|
||||
private Army army;
|
||||
private King king;
|
||||
private Castle castle;
|
||||
private Army army;
|
||||
|
||||
|
||||
/**
|
||||
* Creates kingdom
|
||||
*
|
||||
* @param factory
|
||||
*/
|
||||
public void createKingdom(final KingdomFactory factory) {
|
||||
setKing(factory.createKing());
|
||||
setCastle(factory.createCastle());
|
||||
setArmy(factory.createArmy());
|
||||
}
|
||||
|
||||
ElfKingdomFactory getElfKingdomFactory() {
|
||||
return new ElfKingdomFactory();
|
||||
}
|
||||
|
||||
OrcKingdomFactory getOrcKingdomFactory() {
|
||||
return new OrcKingdomFactory();
|
||||
}
|
||||
|
||||
King getKing(final KingdomFactory factory) {
|
||||
return factory.createKing();
|
||||
}
|
||||
|
||||
Castle getCastle(final KingdomFactory factory) {
|
||||
return factory.createCastle();
|
||||
}
|
||||
|
||||
Army getArmy(final KingdomFactory factory) {
|
||||
return factory.createArmy();
|
||||
}
|
||||
|
||||
public King getKing() {
|
||||
return king;
|
||||
}
|
||||
|
||||
private void setKing(final King king) {
|
||||
this.king = king;
|
||||
}
|
||||
|
||||
public Castle getCastle() {
|
||||
return castle;
|
||||
}
|
||||
|
||||
private void setCastle(final Castle castle) {
|
||||
this.castle = castle;
|
||||
}
|
||||
|
||||
public Army getArmy() {
|
||||
return army;
|
||||
}
|
||||
|
||||
private void setArmy(final Army army) {
|
||||
this.army = army;
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
App app = new App();
|
||||
|
||||
System.out.println("Elf Kingdom");
|
||||
KingdomFactory elfKingdomFactory;
|
||||
elfKingdomFactory = app.getElfKingdomFactory();
|
||||
app.createKingdom(elfKingdomFactory);
|
||||
System.out.println(app.getArmy().getDescription());
|
||||
System.out.println(app.getCastle().getDescription());
|
||||
System.out.println(app.getKing().getDescription());
|
||||
/**
|
||||
* Creates kingdom
|
||||
* @param factory
|
||||
*/
|
||||
public void createKingdom(final KingdomFactory factory) {
|
||||
setKing(factory.createKing());
|
||||
setCastle(factory.createCastle());
|
||||
setArmy(factory.createArmy());
|
||||
}
|
||||
|
||||
System.out.println("\nOrc Kingdom");
|
||||
KingdomFactory orcKingdomFactory;
|
||||
orcKingdomFactory = app.getOrcKingdomFactory();
|
||||
app.createKingdom(orcKingdomFactory);
|
||||
System.out.println(app.getArmy().getDescription());
|
||||
System.out.println(app.getCastle().getDescription());
|
||||
System.out.println(app.getKing().getDescription());
|
||||
|
||||
}
|
||||
|
||||
ElfKingdomFactory getElfKingdomFactory() {
|
||||
return new ElfKingdomFactory();
|
||||
}
|
||||
|
||||
OrcKingdomFactory getOrcKingdomFactory() {
|
||||
return new OrcKingdomFactory();
|
||||
}
|
||||
|
||||
King getKing(final KingdomFactory factory) {
|
||||
return factory.createKing();
|
||||
}
|
||||
|
||||
Castle getCastle(final KingdomFactory factory) {
|
||||
return factory.createCastle();
|
||||
}
|
||||
|
||||
Army getArmy(final KingdomFactory factory) {
|
||||
return factory.createArmy();
|
||||
}
|
||||
|
||||
public King getKing() {
|
||||
return king;
|
||||
}
|
||||
|
||||
private void setKing(final King king) {
|
||||
this.king = king;
|
||||
}
|
||||
|
||||
public Castle getCastle() {
|
||||
return castle;
|
||||
}
|
||||
|
||||
private void setCastle(final Castle castle) {
|
||||
this.castle = castle;
|
||||
}
|
||||
|
||||
public Army getArmy() {
|
||||
return army;
|
||||
}
|
||||
|
||||
private void setArmy(final Army army) {
|
||||
this.army = army;
|
||||
}
|
||||
}
|
||||
|
@ -7,5 +7,5 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public interface Army {
|
||||
|
||||
String getDescription();
|
||||
String getDescription();
|
||||
}
|
||||
|
@ -7,5 +7,5 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public interface Castle {
|
||||
|
||||
String getDescription();
|
||||
String getDescription();
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class ElfArmy implements Army {
|
||||
|
||||
static final String DESCRIPTION = "This is the Elven Army!";
|
||||
static final String DESCRIPTION = "This is the Elven Army!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class ElfCastle implements Castle {
|
||||
|
||||
static final String DESCRIPTION = "This is the Elven castle!";
|
||||
static final String DESCRIPTION = "This is the Elven castle!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class ElfKing implements King {
|
||||
|
||||
static final String DESCRIPTION = "This is the Elven king!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
static final String DESCRIPTION = "This is the Elven king!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,16 +7,16 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class ElfKingdomFactory implements KingdomFactory {
|
||||
|
||||
public Castle createCastle() {
|
||||
return new ElfCastle();
|
||||
}
|
||||
public Castle createCastle() {
|
||||
return new ElfCastle();
|
||||
}
|
||||
|
||||
public King createKing() {
|
||||
return new ElfKing();
|
||||
}
|
||||
public King createKing() {
|
||||
return new ElfKing();
|
||||
}
|
||||
|
||||
public Army createArmy() {
|
||||
return new ElfArmy();
|
||||
}
|
||||
public Army createArmy() {
|
||||
return new ElfArmy();
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,5 +7,5 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public interface King {
|
||||
|
||||
String getDescription();
|
||||
String getDescription();
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public interface KingdomFactory {
|
||||
|
||||
Castle createCastle();
|
||||
Castle createCastle();
|
||||
|
||||
King createKing();
|
||||
King createKing();
|
||||
|
||||
Army createArmy();
|
||||
Army createArmy();
|
||||
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class OrcArmy implements Army {
|
||||
|
||||
static final String DESCRIPTION = "This is the Orc Army!";
|
||||
static final String DESCRIPTION = "This is the Orc Army!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class OrcCastle implements Castle {
|
||||
|
||||
static final String DESCRIPTION = "This is the Orc castle!";
|
||||
static final String DESCRIPTION = "This is the Orc castle!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class OrcKing implements King {
|
||||
|
||||
static final String DESCRIPTION = "This is the Orc king!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
static final String DESCRIPTION = "This is the Orc king!";
|
||||
|
||||
@Override
|
||||
public String getDescription() {
|
||||
return DESCRIPTION;
|
||||
}
|
||||
}
|
||||
|
@ -7,15 +7,16 @@ package com.iluwatar.abstractfactory;
|
||||
*/
|
||||
public class OrcKingdomFactory implements KingdomFactory {
|
||||
|
||||
public Castle createCastle() {
|
||||
return new OrcCastle();
|
||||
}
|
||||
public Castle createCastle() {
|
||||
return new OrcCastle();
|
||||
}
|
||||
|
||||
public King createKing() {
|
||||
return new OrcKing();
|
||||
}
|
||||
public King createKing() {
|
||||
return new OrcKing();
|
||||
}
|
||||
|
||||
public Army createArmy() {
|
||||
return new OrcArmy();
|
||||
}
|
||||
|
||||
public Army createArmy() {
|
||||
return new OrcArmy();
|
||||
}
|
||||
}
|
||||
|
@ -1,5 +1,4 @@
|
||||
package com.iluwatar.abstractfactory;
|
||||
|
||||
import static org.junit.Assert.assertEquals;
|
||||
import static org.junit.Assert.assertTrue;
|
||||
|
||||
@ -8,71 +7,71 @@ import org.junit.Test;
|
||||
|
||||
public class AppTest {
|
||||
|
||||
private App app = new App();
|
||||
private KingdomFactory elfFactory;
|
||||
private KingdomFactory orcFactory;
|
||||
|
||||
@Before
|
||||
public void setUp() {
|
||||
elfFactory = app.getElfKingdomFactory();
|
||||
orcFactory = app.getOrcKingdomFactory();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void king() {
|
||||
final King elfKing = app.getKing(elfFactory);
|
||||
assertTrue(elfKing instanceof ElfKing);
|
||||
assertEquals(ElfKing.DESCRIPTION, elfKing.getDescription());
|
||||
final King orcKing = app.getKing(orcFactory);
|
||||
assertTrue(orcKing instanceof OrcKing);
|
||||
assertEquals(OrcKing.DESCRIPTION, orcKing.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void castle() {
|
||||
final Castle elfCastle = app.getCastle(elfFactory);
|
||||
assertTrue(elfCastle instanceof ElfCastle);
|
||||
assertEquals(ElfCastle.DESCRIPTION, elfCastle.getDescription());
|
||||
final Castle orcCastle = app.getCastle(orcFactory);
|
||||
assertTrue(orcCastle instanceof OrcCastle);
|
||||
assertEquals(OrcCastle.DESCRIPTION, orcCastle.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void army() {
|
||||
final Army elfArmy = app.getArmy(elfFactory);
|
||||
assertTrue(elfArmy instanceof ElfArmy);
|
||||
assertEquals(ElfArmy.DESCRIPTION, elfArmy.getDescription());
|
||||
final Army orcArmy = app.getArmy(orcFactory);
|
||||
assertTrue(orcArmy instanceof OrcArmy);
|
||||
assertEquals(OrcArmy.DESCRIPTION, orcArmy.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void createElfKingdom() {
|
||||
app.createKingdom(elfFactory);
|
||||
final King king = app.getKing();
|
||||
final Castle castle = app.getCastle();
|
||||
final Army army = app.getArmy();
|
||||
assertTrue(king instanceof ElfKing);
|
||||
assertEquals(ElfKing.DESCRIPTION, king.getDescription());
|
||||
assertTrue(castle instanceof ElfCastle);
|
||||
assertEquals(ElfCastle.DESCRIPTION, castle.getDescription());
|
||||
assertTrue(army instanceof ElfArmy);
|
||||
assertEquals(ElfArmy.DESCRIPTION, army.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void createOrcKingdom() {
|
||||
app.createKingdom(orcFactory);
|
||||
final King king = app.getKing();
|
||||
final Castle castle = app.getCastle();
|
||||
final Army army = app.getArmy();
|
||||
assertTrue(king instanceof OrcKing);
|
||||
assertEquals(OrcKing.DESCRIPTION, king.getDescription());
|
||||
assertTrue(castle instanceof OrcCastle);
|
||||
assertEquals(OrcCastle.DESCRIPTION, castle.getDescription());
|
||||
assertTrue(army instanceof OrcArmy);
|
||||
assertEquals(OrcArmy.DESCRIPTION, army.getDescription());
|
||||
}
|
||||
private App app = new App();;
|
||||
private KingdomFactory elfFactory;
|
||||
private KingdomFactory orcFactory;
|
||||
|
||||
@Before
|
||||
public void setUp() {
|
||||
elfFactory = app.getElfKingdomFactory();
|
||||
orcFactory = app.getOrcKingdomFactory();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void king() {
|
||||
final King elfKing = app.getKing(elfFactory);
|
||||
assertTrue(elfKing instanceof ElfKing);
|
||||
assertEquals(ElfKing.DESCRIPTION, elfKing.getDescription());
|
||||
final King orcKing = app.getKing(orcFactory);
|
||||
assertTrue(orcKing instanceof OrcKing);
|
||||
assertEquals(OrcKing.DESCRIPTION, orcKing.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void castle() {
|
||||
final Castle elfCastle = app.getCastle(elfFactory);
|
||||
assertTrue(elfCastle instanceof ElfCastle);
|
||||
assertEquals(ElfCastle.DESCRIPTION, elfCastle.getDescription());
|
||||
final Castle orcCastle = app.getCastle(orcFactory);
|
||||
assertTrue(orcCastle instanceof OrcCastle);
|
||||
assertEquals(OrcCastle.DESCRIPTION, orcCastle.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void army() {
|
||||
final Army elfArmy = app.getArmy(elfFactory);
|
||||
assertTrue(elfArmy instanceof ElfArmy);
|
||||
assertEquals(ElfArmy.DESCRIPTION, elfArmy.getDescription());
|
||||
final Army orcArmy = app.getArmy(orcFactory);
|
||||
assertTrue(orcArmy instanceof OrcArmy);
|
||||
assertEquals(OrcArmy.DESCRIPTION, orcArmy.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void createElfKingdom() {
|
||||
app.createKingdom(elfFactory);
|
||||
final King king = app.getKing();
|
||||
final Castle castle = app.getCastle();
|
||||
final Army army = app.getArmy();
|
||||
assertTrue(king instanceof ElfKing);
|
||||
assertEquals(ElfKing.DESCRIPTION, king.getDescription());
|
||||
assertTrue(castle instanceof ElfCastle);
|
||||
assertEquals(ElfCastle.DESCRIPTION, castle.getDescription());
|
||||
assertTrue(army instanceof ElfArmy);
|
||||
assertEquals(ElfArmy.DESCRIPTION, army.getDescription());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void createOrcKingdom() {
|
||||
app.createKingdom(orcFactory);
|
||||
final King king = app.getKing();
|
||||
final Castle castle = app.getCastle();
|
||||
final Army army = app.getArmy();
|
||||
assertTrue(king instanceof OrcKing);
|
||||
assertEquals(OrcKing.DESCRIPTION, king.getDescription());
|
||||
assertTrue(castle instanceof OrcCastle);
|
||||
assertEquals(OrcCastle.DESCRIPTION, castle.getDescription());
|
||||
assertTrue(army instanceof OrcArmy);
|
||||
assertEquals(OrcArmy.DESCRIPTION, army.getDescription());
|
||||
}
|
||||
}
|
||||
|
@ -4,13 +4,9 @@ title: Adapter
|
||||
folder: adapter
|
||||
permalink: /patterns/adapter/
|
||||
categories: Structural
|
||||
tags:
|
||||
- Java
|
||||
- Gang Of Four
|
||||
tags: Java
|
||||
---
|
||||
|
||||
**Also known as:** Wrapper
|
||||
|
||||
**Intent:** Convert the interface of a class into another interface the clients
|
||||
expect. Adapter lets classes work together that couldn't otherwise because of
|
||||
incompatible interfaces.
|
||||
@ -26,7 +22,3 @@ incompatible interfaces.
|
||||
**Real world examples:**
|
||||
|
||||
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
|
@ -1,23 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>adapter</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
<dependency>
|
||||
<groupId>org.mockito</groupId>
|
||||
<artifactId>mockito-core</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>adapter</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -1,28 +1,25 @@
|
||||
package com.iluwatar.adapter;
|
||||
|
||||
/**
|
||||
* An adapter helps two incompatible interfaces to work together. This is the real world definition
|
||||
* for an adapter. Interfaces may be incompatible but the inner functionality should suit the need.
|
||||
* The Adapter design pattern allows otherwise incompatible classes to work together by converting
|
||||
* the interface of one class into an interface expected by the clients.
|
||||
*
|
||||
* <p>There are two variations of the Adapter pattern: The class adapter implements the adaptee's
|
||||
* interface whereas the object adapter uses composition to contain the adaptee in the adapter
|
||||
* object. This example uses the object adapter approach.
|
||||
* There are two variations of the Adapter pattern: The class adapter implements
|
||||
* the adaptee's interface whereas the object adapter uses composition to
|
||||
* contain the adaptee in the adapter object. This example uses the object
|
||||
* adapter approach.
|
||||
* <p>
|
||||
* The Adapter ({@link GnomeEngineer}) converts the interface of the target class
|
||||
* ({@link GoblinGlider}) into a suitable one expected by the client
|
||||
* ({@link GnomeEngineeringManager}).
|
||||
*
|
||||
* <p>The Adapter ({@link GnomeEngineer}) converts the interface of the target class (
|
||||
* {@link GoblinGlider}) into a suitable one expected by the client ({@link GnomeEngineeringManager}
|
||||
* ).
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point.
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
Engineer manager = new GnomeEngineeringManager(new GnomeEngineer());
|
||||
manager.operateDevice();
|
||||
}
|
||||
/**
|
||||
* Program entry point
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
Engineer manager = new GnomeEngineeringManager();
|
||||
manager.operateDevice();
|
||||
}
|
||||
}
|
||||
|
@ -7,5 +7,6 @@ package com.iluwatar.adapter;
|
||||
*/
|
||||
public interface Engineer {
|
||||
|
||||
void operateDevice();
|
||||
void operateDevice();
|
||||
|
||||
}
|
||||
|
@ -2,22 +2,23 @@ package com.iluwatar.adapter;
|
||||
|
||||
/**
|
||||
*
|
||||
* Adapter class. Adapts the interface of the device ({@link GoblinGlider}) into {@link Engineer}
|
||||
* interface expected by the client ({@link GnomeEngineeringManager}).
|
||||
* Adapter class. Adapts the interface of the device ({@link GoblinGlider}) into
|
||||
* {@link Engineer} interface expected by the client ({@link GnomeEngineeringManager}).
|
||||
*
|
||||
*/
|
||||
public class GnomeEngineer implements Engineer {
|
||||
|
||||
private GoblinGlider glider;
|
||||
private GoblinGlider glider;
|
||||
|
||||
public GnomeEngineer() {
|
||||
glider = new GoblinGlider();
|
||||
}
|
||||
public GnomeEngineer() {
|
||||
glider = new GoblinGlider();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void operateDevice() {
|
||||
glider.attachGlider();
|
||||
glider.gainSpeed();
|
||||
glider.takeOff();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void operateDevice() {
|
||||
glider.attachGlider();
|
||||
glider.gainSpeed();
|
||||
glider.takeOff();
|
||||
}
|
||||
}
|
||||
|
@ -1,26 +1,20 @@
|
||||
package com.iluwatar.adapter;
|
||||
|
||||
/**
|
||||
*
|
||||
* GnomeEngineering manager uses {@link Engineer} to operate devices.
|
||||
*
|
||||
*/
|
||||
public class GnomeEngineeringManager implements Engineer {
|
||||
|
||||
private Engineer engineer;
|
||||
private Engineer engineer;
|
||||
|
||||
public GnomeEngineeringManager() {
|
||||
public GnomeEngineeringManager() {
|
||||
engineer = new GnomeEngineer();
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
public GnomeEngineeringManager(Engineer engineer) {
|
||||
this.engineer = engineer;
|
||||
}
|
||||
|
||||
@Override
|
||||
public void operateDevice() {
|
||||
engineer.operateDevice();
|
||||
}
|
||||
|
||||
public void setEngineer(Engineer engineer) {
|
||||
this.engineer = engineer;
|
||||
}
|
||||
@Override
|
||||
public void operateDevice() {
|
||||
engineer.operateDevice();
|
||||
}
|
||||
}
|
||||
|
@ -7,15 +7,15 @@ package com.iluwatar.adapter;
|
||||
*/
|
||||
public class GoblinGlider {
|
||||
|
||||
public void attachGlider() {
|
||||
System.out.println("Glider attached.");
|
||||
}
|
||||
public void attachGlider() {
|
||||
System.out.println("Glider attached.");
|
||||
}
|
||||
|
||||
public void gainSpeed() {
|
||||
System.out.println("Gaining speed.");
|
||||
}
|
||||
public void gainSpeed() {
|
||||
System.out.println("Gaining speed.");
|
||||
}
|
||||
|
||||
public void takeOff() {
|
||||
System.out.println("Lift-off!");
|
||||
}
|
||||
public void takeOff() {
|
||||
System.out.println("Lift-off!");
|
||||
}
|
||||
}
|
||||
|
@ -1,68 +0,0 @@
|
||||
package com.iluwatar.adapter;
|
||||
|
||||
import static org.mockito.Mockito.spy;
|
||||
import static org.mockito.Mockito.verify;
|
||||
|
||||
import java.util.HashMap;
|
||||
import java.util.Map;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
/**
|
||||
* An adapter helps two incompatible interfaces to work together. This is the real world definition
|
||||
* for an adapter. Interfaces may be incompatible but the inner functionality should suit the need.
|
||||
* The Adapter design pattern allows otherwise incompatible classes to work together by converting
|
||||
* the interface of one class into an interface expected by the clients.
|
||||
*
|
||||
* <p>There are two variations of the Adapter pattern:
|
||||
* The class adapter implements the adaptee's
|
||||
* interface whereas the object adapter uses composition to contain the adaptee in the adapter
|
||||
* object. This example uses the object adapter approach.
|
||||
*
|
||||
* <p>The Adapter ({@link GnomeEngineer}) converts the interface
|
||||
* of the target class ({@link GoblinGlider}) into a suitable one expected by
|
||||
* the client ({@link GnomeEngineeringManager}
|
||||
* ).
|
||||
*/
|
||||
public class AdapterPatternTest {
|
||||
|
||||
private Map<String, Object> beans;
|
||||
|
||||
private static final String ENGINEER_BEAN = "engineer";
|
||||
|
||||
private static final String MANAGER_BEAN = "manager";
|
||||
|
||||
/**
|
||||
* This method runs before the test execution and sets the bean objects in the beans Map.
|
||||
*/
|
||||
@Before
|
||||
public void setup() {
|
||||
beans = new HashMap<>();
|
||||
|
||||
GnomeEngineer gnomeEngineer = spy(new GnomeEngineer());
|
||||
beans.put(ENGINEER_BEAN, gnomeEngineer);
|
||||
|
||||
GnomeEngineeringManager manager = new GnomeEngineeringManager();
|
||||
manager.setEngineer((GnomeEngineer) beans.get(ENGINEER_BEAN));
|
||||
beans.put(MANAGER_BEAN, manager);
|
||||
}
|
||||
|
||||
/**
|
||||
* This test asserts that when we call operateDevice() method on a manager bean, it is internally
|
||||
* calling operateDevice method on the engineer object. The Adapter ({@link GnomeEngineer})
|
||||
* converts the interface of the target class ( {@link GoblinGlider}) into a suitable one expected
|
||||
* by the client ({@link GnomeEngineeringManager} ).
|
||||
*/
|
||||
@Test
|
||||
public void testAdapter() {
|
||||
Engineer manager = (Engineer) beans.get(MANAGER_BEAN);
|
||||
|
||||
// when manager is asked to operate device
|
||||
manager.operateDevice();
|
||||
|
||||
// Manager internally calls the engineer object to operateDevice
|
||||
Engineer engineer = (Engineer) beans.get(ENGINEER_BEAN);
|
||||
verify(engineer).operateDevice();
|
||||
}
|
||||
}
|
19
adapter/src/test/java/com/iluwatar/adapter/AppTest.java
Normal file
19
adapter/src/test/java/com/iluwatar/adapter/AppTest.java
Normal file
@ -0,0 +1,19 @@
|
||||
package com.iluwatar.adapter;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
import com.iluwatar.adapter.App;
|
||||
|
||||
/**
|
||||
*
|
||||
* Application test
|
||||
*
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
}
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>async-method-invocation</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>async-method-invocation</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -4,24 +4,23 @@ import java.util.concurrent.Callable;
|
||||
|
||||
/**
|
||||
* This application demonstrates the async method invocation pattern. Key parts of the pattern are
|
||||
* <code>AsyncResult</code> which is an intermediate container for an asynchronously evaluated
|
||||
* value, <code>AsyncCallback</code> which can be provided to be executed on task completion and
|
||||
* <code>AsyncResult</code> which is an intermediate container for an asynchronously evaluated value,
|
||||
* <code>AsyncCallback</code> which can be provided to be executed on task completion and
|
||||
* <code>AsyncExecutor</code> that manages the execution of the async tasks.
|
||||
* <p>
|
||||
* The main method shows example flow of async invocations. The main thread starts multiple tasks
|
||||
* with variable durations and then continues its own work. When the main thread has done it's job
|
||||
* it collects the results of the async tasks. Two of the tasks are handled with callbacks, meaning
|
||||
* the callbacks are executed immediately when the tasks complete.
|
||||
* The main method shows example flow of async invocations. The main thread starts multiple tasks with
|
||||
* variable durations and then continues its own work. When the main thread has done it's job it collects
|
||||
* the results of the async tasks. Two of the tasks are handled with callbacks, meaning the callbacks are
|
||||
* executed immediately when the tasks complete.
|
||||
* <p>
|
||||
* Noteworthy difference of thread usage between the async results and callbacks is that the async
|
||||
* results are collected in the main thread but the callbacks are executed within the worker
|
||||
* threads. This should be noted when working with thread pools.
|
||||
* Noteworthy difference of thread usage between the async results and callbacks is that the async results
|
||||
* are collected in the main thread but the callbacks are executed within the worker threads. This should be
|
||||
* noted when working with thread pools.
|
||||
* <p>
|
||||
* Java provides its own implementations of async method invocation pattern. FutureTask,
|
||||
* CompletableFuture and ExecutorService are the real world implementations of this pattern. But due
|
||||
* to the nature of parallel programming, the implementations are not trivial. This example does not
|
||||
* take all possible scenarios into account but rather provides a simple version that helps to
|
||||
* understand the pattern.
|
||||
* Java provides its own implementations of async method invocation pattern. FutureTask, CompletableFuture
|
||||
* and ExecutorService are the real world implementations of this pattern. But due to the nature of parallel
|
||||
* programming, the implementations are not trivial. This example does not take all possible scenarios into
|
||||
* account but rather provides a simple version that helps to understand the pattern.
|
||||
*
|
||||
* @see AsyncResult
|
||||
* @see AsyncCallback
|
||||
@ -33,68 +32,66 @@ import java.util.concurrent.Callable;
|
||||
*/
|
||||
public class App {
|
||||
|
||||
public static void main(String[] args) throws Exception {
|
||||
// construct a new executor that will run async tasks
|
||||
AsyncExecutor executor = new ThreadAsyncExecutor();
|
||||
public static void main(String[] args) throws Exception {
|
||||
// construct a new executor that will run async tasks
|
||||
AsyncExecutor executor = new ThreadAsyncExecutor();
|
||||
|
||||
// start few async tasks with varying processing times, two last with callback handlers
|
||||
AsyncResult<Integer> asyncResult1 = executor.startProcess(lazyval(10, 500));
|
||||
AsyncResult<String> asyncResult2 = executor.startProcess(lazyval("test", 300));
|
||||
AsyncResult<Long> asyncResult3 = executor.startProcess(lazyval(50L, 700));
|
||||
AsyncResult<Integer> asyncResult4 =
|
||||
executor.startProcess(lazyval(20, 400), callback("Callback result 4"));
|
||||
AsyncResult<String> asyncResult5 =
|
||||
executor.startProcess(lazyval("callback", 600), callback("Callback result 5"));
|
||||
// start few async tasks with varying processing times, two last with callback handlers
|
||||
AsyncResult<Integer> asyncResult1 = executor.startProcess(lazyval(10, 500));
|
||||
AsyncResult<String> asyncResult2 = executor.startProcess(lazyval("test", 300));
|
||||
AsyncResult<Long> asyncResult3 = executor.startProcess(lazyval(50L, 700));
|
||||
AsyncResult<Integer> asyncResult4 = executor.startProcess(lazyval(20, 400), callback("Callback result 4"));
|
||||
AsyncResult<String> asyncResult5 = executor.startProcess(lazyval("callback", 600), callback("Callback result 5"));
|
||||
|
||||
// emulate processing in the current thread while async tasks are running in their own threads
|
||||
Thread.sleep(350); // Oh boy I'm working hard here
|
||||
log("Some hard work done");
|
||||
// emulate processing in the current thread while async tasks are running in their own threads
|
||||
Thread.sleep(350); // Oh boy I'm working hard here
|
||||
log("Some hard work done");
|
||||
|
||||
// wait for completion of the tasks
|
||||
Integer result1 = executor.endProcess(asyncResult1);
|
||||
String result2 = executor.endProcess(asyncResult2);
|
||||
Long result3 = executor.endProcess(asyncResult3);
|
||||
asyncResult4.await();
|
||||
asyncResult5.await();
|
||||
// wait for completion of the tasks
|
||||
Integer result1 = executor.endProcess(asyncResult1);
|
||||
String result2 = executor.endProcess(asyncResult2);
|
||||
Long result3 = executor.endProcess(asyncResult3);
|
||||
asyncResult4.await();
|
||||
asyncResult5.await();
|
||||
|
||||
// log the results of the tasks, callbacks log immediately when complete
|
||||
log("Result 1: " + result1);
|
||||
log("Result 2: " + result2);
|
||||
log("Result 3: " + result3);
|
||||
}
|
||||
// log the results of the tasks, callbacks log immediately when complete
|
||||
log("Result 1: " + result1);
|
||||
log("Result 2: " + result2);
|
||||
log("Result 3: " + result3);
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates a callable that lazily evaluates to given value with artificial delay.
|
||||
*
|
||||
* @param value value to evaluate
|
||||
* @param delayMillis artificial delay in milliseconds
|
||||
* @return new callable for lazy evaluation
|
||||
*/
|
||||
private static <T> Callable<T> lazyval(T value, long delayMillis) {
|
||||
return () -> {
|
||||
Thread.sleep(delayMillis);
|
||||
log("Task completed with: " + value);
|
||||
return value;
|
||||
};
|
||||
}
|
||||
/**
|
||||
* Creates a callable that lazily evaluates to given value with artificial delay.
|
||||
*
|
||||
* @param value value to evaluate
|
||||
* @param delayMillis artificial delay in milliseconds
|
||||
* @return new callable for lazy evaluation
|
||||
*/
|
||||
private static <T> Callable<T> lazyval(T value, long delayMillis) {
|
||||
return () -> {
|
||||
Thread.sleep(delayMillis);
|
||||
log("Task completed with: " + value);
|
||||
return value;
|
||||
};
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates a simple callback that logs the complete status of the async result.
|
||||
*
|
||||
* @param name callback name
|
||||
* @return new async callback
|
||||
*/
|
||||
private static <T> AsyncCallback<T> callback(String name) {
|
||||
return (value, ex) -> {
|
||||
if (ex.isPresent()) {
|
||||
log(name + " failed: " + ex.map(Exception::getMessage).orElse(""));
|
||||
} else {
|
||||
log(name + ": " + value);
|
||||
}
|
||||
};
|
||||
}
|
||||
/**
|
||||
* Creates a simple callback that logs the complete status of the async result.
|
||||
*
|
||||
* @param name callback name
|
||||
* @return new async callback
|
||||
*/
|
||||
private static <T> AsyncCallback<T> callback(String name) {
|
||||
return (value, ex) -> {
|
||||
if (ex.isPresent()) {
|
||||
log(name + " failed: " + ex.map(Exception::getMessage).orElse(""));
|
||||
} else {
|
||||
log(name + ": " + value);
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
private static void log(String msg) {
|
||||
System.out.println(String.format("[%1$-10s] - %2$s", Thread.currentThread().getName(), msg));
|
||||
}
|
||||
private static void log(String msg) {
|
||||
System.out.println(String.format("[%1$-10s] - %2$s", Thread.currentThread().getName(), msg));
|
||||
}
|
||||
}
|
||||
|
@ -11,11 +11,12 @@ import java.util.Optional;
|
||||
*/
|
||||
public interface AsyncCallback<T> {
|
||||
|
||||
/**
|
||||
* Complete handler which is executed when async task is completed or fails execution.
|
||||
*
|
||||
* @param value the evaluated value from async task, undefined when execution fails
|
||||
* @param ex empty value if execution succeeds, some exception if executions fails
|
||||
*/
|
||||
void onComplete(T value, Optional<Exception> ex);
|
||||
/**
|
||||
* Complete handler which is executed when async task is completed or fails execution.
|
||||
*
|
||||
* @param value the evaluated value from async task, undefined when execution fails
|
||||
* @param ex empty value if execution succeeds, some exception if executions fails
|
||||
*/
|
||||
void onComplete(T value, Optional<Exception> ex);
|
||||
|
||||
}
|
||||
|
@ -10,32 +10,33 @@ import java.util.concurrent.ExecutionException;
|
||||
*/
|
||||
public interface AsyncExecutor {
|
||||
|
||||
/**
|
||||
* Starts processing of an async task. Returns immediately with async result.
|
||||
*
|
||||
* @param task task to be executed asynchronously
|
||||
* @return async result for the task
|
||||
*/
|
||||
<T> AsyncResult<T> startProcess(Callable<T> task);
|
||||
/**
|
||||
* Starts processing of an async task. Returns immediately with async result.
|
||||
*
|
||||
* @param task task to be executed asynchronously
|
||||
* @return async result for the task
|
||||
*/
|
||||
<T> AsyncResult<T> startProcess(Callable<T> task);
|
||||
|
||||
/**
|
||||
* Starts processing of an async task. Returns immediately with async result. Executes callback
|
||||
* when the task is completed.
|
||||
*
|
||||
* @param task task to be executed asynchronously
|
||||
* @param callback callback to be executed on task completion
|
||||
* @return async result for the task
|
||||
*/
|
||||
<T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);
|
||||
/**
|
||||
* Starts processing of an async task. Returns immediately with async result. Executes callback
|
||||
* when the task is completed.
|
||||
*
|
||||
* @param task task to be executed asynchronously
|
||||
* @param callback callback to be executed on task completion
|
||||
* @return async result for the task
|
||||
*/
|
||||
<T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);
|
||||
|
||||
/**
|
||||
* Ends processing of an async task. Blocks the current thread if necessary and returns the
|
||||
* evaluated value of the completed task.
|
||||
*
|
||||
* @param asyncResult async result of a task
|
||||
* @return evaluated value of the completed task
|
||||
* @throws ExecutionException if execution has failed, containing the root cause
|
||||
* @throws InterruptedException if the execution is interrupted
|
||||
*/
|
||||
<T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
|
||||
|
||||
/**
|
||||
* Ends processing of an async task. Blocks the current thread if necessary and returns the
|
||||
* evaluated value of the completed task.
|
||||
*
|
||||
* @param asyncResult async result of a task
|
||||
* @return evaluated value of the completed task
|
||||
* @throws ExecutionException if execution has failed, containing the root cause
|
||||
* @throws InterruptedException if the execution is interrupted
|
||||
*/
|
||||
<T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
|
||||
}
|
||||
|
@ -10,26 +10,26 @@ import java.util.concurrent.ExecutionException;
|
||||
*/
|
||||
public interface AsyncResult<T> {
|
||||
|
||||
/**
|
||||
* Status of the async task execution.
|
||||
*
|
||||
* @return <code>true</code> if execution is completed or failed
|
||||
*/
|
||||
boolean isCompleted();
|
||||
/**
|
||||
* Status of the async task execution.
|
||||
*
|
||||
* @return <code>true</code> if execution is completed or failed
|
||||
*/
|
||||
boolean isCompleted();
|
||||
|
||||
/**
|
||||
* Gets the value of completed async task.
|
||||
*
|
||||
* @return evaluated value or throws ExecutionException if execution has failed
|
||||
* @throws ExecutionException if execution has failed, containing the root cause
|
||||
* @throws IllegalStateException if execution is not completed
|
||||
*/
|
||||
T getValue() throws ExecutionException;
|
||||
/**
|
||||
* Gets the value of completed async task.
|
||||
*
|
||||
* @return evaluated value or throws ExecutionException if execution has failed
|
||||
* @throws ExecutionException if execution has failed, containing the root cause
|
||||
* @throws IllegalStateException if execution is not completed
|
||||
*/
|
||||
T getValue() throws ExecutionException;
|
||||
|
||||
/**
|
||||
* Blocks the current thread until the async task is completed.
|
||||
*
|
||||
* @throws InterruptedException if the execution is interrupted
|
||||
*/
|
||||
void await() throws InterruptedException;
|
||||
/**
|
||||
* Blocks the current thread until the async task is completed.
|
||||
*
|
||||
* @throws InterruptedException if the execution is interrupted
|
||||
*/
|
||||
void await() throws InterruptedException;
|
||||
}
|
||||
|
@ -12,117 +12,116 @@ import java.util.concurrent.atomic.AtomicInteger;
|
||||
*/
|
||||
public class ThreadAsyncExecutor implements AsyncExecutor {
|
||||
|
||||
/** Index for thread naming */
|
||||
private final AtomicInteger idx = new AtomicInteger(0);
|
||||
/** Index for thread naming */
|
||||
private final AtomicInteger idx = new AtomicInteger(0);
|
||||
|
||||
@Override
|
||||
public <T> AsyncResult<T> startProcess(Callable<T> task) {
|
||||
return startProcess(task, null);
|
||||
}
|
||||
@Override
|
||||
public <T> AsyncResult<T> startProcess(Callable<T> task) {
|
||||
return startProcess(task, null);
|
||||
}
|
||||
|
||||
@Override
|
||||
public <T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback) {
|
||||
CompletableResult<T> result = new CompletableResult<>(callback);
|
||||
new Thread(() -> {
|
||||
try {
|
||||
result.setValue(task.call());
|
||||
} catch (Exception ex) {
|
||||
result.setException(ex);
|
||||
}
|
||||
}, "executor-" + idx.incrementAndGet()).start();
|
||||
return result;
|
||||
}
|
||||
@Override
|
||||
public <T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback) {
|
||||
CompletableResult<T> result = new CompletableResult<>(callback);
|
||||
new Thread(() -> {
|
||||
try {
|
||||
result.setValue(task.call());
|
||||
} catch (Exception ex) {
|
||||
result.setException(ex);
|
||||
}
|
||||
}, "executor-" + idx.incrementAndGet()).start();
|
||||
return result;
|
||||
}
|
||||
|
||||
@Override
|
||||
public <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException,
|
||||
InterruptedException {
|
||||
if (asyncResult.isCompleted()) {
|
||||
return asyncResult.getValue();
|
||||
} else {
|
||||
asyncResult.await();
|
||||
return asyncResult.getValue();
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public <T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException {
|
||||
if (asyncResult.isCompleted()) {
|
||||
return asyncResult.getValue();
|
||||
} else {
|
||||
asyncResult.await();
|
||||
return asyncResult.getValue();
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Simple implementation of async result that allows completing it successfully with a value or
|
||||
* exceptionally with an exception. A really simplified version from its real life cousins
|
||||
* FutureTask and CompletableFuture.
|
||||
*
|
||||
* @see java.util.concurrent.FutureTask
|
||||
* @see java.util.concurrent.CompletableFuture
|
||||
*/
|
||||
private static class CompletableResult<T> implements AsyncResult<T> {
|
||||
/**
|
||||
* Simple implementation of async result that allows completing it successfully with a value
|
||||
* or exceptionally with an exception. A really simplified version from its real life cousins
|
||||
* FutureTask and CompletableFuture.
|
||||
*
|
||||
* @see java.util.concurrent.FutureTask
|
||||
* @see java.util.concurrent.CompletableFuture
|
||||
*/
|
||||
private static class CompletableResult<T> implements AsyncResult<T> {
|
||||
|
||||
static final int RUNNING = 1;
|
||||
static final int FAILED = 2;
|
||||
static final int COMPLETED = 3;
|
||||
static final int RUNNING = 1;
|
||||
static final int FAILED = 2;
|
||||
static final int COMPLETED = 3;
|
||||
|
||||
final Object lock;
|
||||
final Optional<AsyncCallback<T>> callback;
|
||||
final Object lock;
|
||||
final Optional<AsyncCallback<T>> callback;
|
||||
|
||||
volatile int state = RUNNING;
|
||||
T value;
|
||||
Exception exception;
|
||||
volatile int state = RUNNING;
|
||||
T value;
|
||||
Exception exception;
|
||||
|
||||
CompletableResult(AsyncCallback<T> callback) {
|
||||
this.lock = new Object();
|
||||
this.callback = Optional.ofNullable(callback);
|
||||
}
|
||||
CompletableResult(AsyncCallback<T> callback) {
|
||||
this.lock = new Object();
|
||||
this.callback = Optional.ofNullable(callback);
|
||||
}
|
||||
|
||||
/**
|
||||
* Sets the value from successful execution and executes callback if available. Notifies any
|
||||
* thread waiting for completion.
|
||||
*
|
||||
* @param value value of the evaluated task
|
||||
*/
|
||||
void setValue(T value) {
|
||||
this.value = value;
|
||||
this.state = COMPLETED;
|
||||
this.callback.ifPresent(ac -> ac.onComplete(value, Optional.<Exception>empty()));
|
||||
synchronized (lock) {
|
||||
lock.notifyAll();
|
||||
}
|
||||
}
|
||||
/**
|
||||
* Sets the value from successful execution and executes callback if available. Notifies
|
||||
* any thread waiting for completion.
|
||||
*
|
||||
* @param value value of the evaluated task
|
||||
*/
|
||||
void setValue(T value) {
|
||||
this.value = value;
|
||||
this.state = COMPLETED;
|
||||
this.callback.ifPresent(ac -> ac.onComplete(value, Optional.<Exception>empty()));
|
||||
synchronized (lock) {
|
||||
lock.notifyAll();
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Sets the exception from failed execution and executes callback if available. Notifies any
|
||||
* thread waiting for completion.
|
||||
*
|
||||
* @param exception exception of the failed task
|
||||
*/
|
||||
void setException(Exception exception) {
|
||||
this.exception = exception;
|
||||
this.state = FAILED;
|
||||
this.callback.ifPresent(ac -> ac.onComplete(null, Optional.of(exception)));
|
||||
synchronized (lock) {
|
||||
lock.notifyAll();
|
||||
}
|
||||
}
|
||||
/**
|
||||
* Sets the exception from failed execution and executes callback if available. Notifies
|
||||
* any thread waiting for completion.
|
||||
*
|
||||
* @param exception exception of the failed task
|
||||
*/
|
||||
void setException(Exception exception) {
|
||||
this.exception = exception;
|
||||
this.state = FAILED;
|
||||
this.callback.ifPresent(ac -> ac.onComplete(null, Optional.of(exception)));
|
||||
synchronized (lock) {
|
||||
lock.notifyAll();
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public boolean isCompleted() {
|
||||
return (state > RUNNING);
|
||||
}
|
||||
@Override
|
||||
public boolean isCompleted() {
|
||||
return (state > RUNNING);
|
||||
}
|
||||
|
||||
@Override
|
||||
public T getValue() throws ExecutionException {
|
||||
if (state == COMPLETED) {
|
||||
return value;
|
||||
} else if (state == FAILED) {
|
||||
throw new ExecutionException(exception);
|
||||
} else {
|
||||
throw new IllegalStateException("Execution not completed yet");
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public T getValue() throws ExecutionException {
|
||||
if (state == COMPLETED) {
|
||||
return value;
|
||||
} else if (state == FAILED) {
|
||||
throw new ExecutionException(exception);
|
||||
} else {
|
||||
throw new IllegalStateException("Execution not completed yet");
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public void await() throws InterruptedException {
|
||||
synchronized (lock) {
|
||||
if (!isCompleted()) {
|
||||
lock.wait();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public void await() throws InterruptedException {
|
||||
synchronized (lock) {
|
||||
if (!isCompleted()) {
|
||||
lock.wait();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
@ -9,9 +9,10 @@ import org.junit.Test;
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
@Test
|
||||
public void test() throws Exception {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
@Test
|
||||
public void test() throws Exception {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -4,13 +4,9 @@ title: Bridge
|
||||
folder: bridge
|
||||
permalink: /patterns/bridge/
|
||||
categories: Structural
|
||||
tags:
|
||||
- Java
|
||||
- Gang Of Four
|
||||
tags: Java
|
||||
---
|
||||
|
||||
**Also known as:** Handle/Body
|
||||
|
||||
**Intent:** Decouple an abstraction from its implementation so that the two can
|
||||
vary independently.
|
||||
|
||||
@ -24,7 +20,3 @@ vary independently.
|
||||
* changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled.
|
||||
* you have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies
|
||||
* you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation.
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>bridge</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>bridge</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -2,38 +2,38 @@ package com.iluwatar.bridge;
|
||||
|
||||
/**
|
||||
*
|
||||
* The Bridge pattern can also be thought of as two layers of abstraction. With Bridge, you can
|
||||
* decouple an abstraction from its implementation so that the two can vary independently.
|
||||
* <p>
|
||||
* In Bridge pattern both abstraction ({@link MagicWeapon}) and implementation (
|
||||
* {@link MagicWeaponImpl}) have their own class hierarchies. The interface of the implementations
|
||||
* can be changed without affecting the clients.
|
||||
* In Bridge pattern both abstraction ({@link MagicWeapon}) and implementation
|
||||
* ({@link MagicWeaponImpl}) have their own class hierarchies. The interface of the
|
||||
* implementations can be changed without affecting the clients.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(new Excalibur());
|
||||
blindingMagicWeapon.wield();
|
||||
blindingMagicWeapon.blind();
|
||||
blindingMagicWeapon.swing();
|
||||
blindingMagicWeapon.unwield();
|
||||
/**
|
||||
* Program entry point
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
BlindingMagicWeapon blindingMagicWeapon = new BlindingMagicWeapon(
|
||||
new Excalibur());
|
||||
blindingMagicWeapon.wield();
|
||||
blindingMagicWeapon.blind();
|
||||
blindingMagicWeapon.swing();
|
||||
blindingMagicWeapon.unwield();
|
||||
|
||||
FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(new Mjollnir());
|
||||
flyingMagicWeapon.wield();
|
||||
flyingMagicWeapon.fly();
|
||||
flyingMagicWeapon.swing();
|
||||
flyingMagicWeapon.unwield();
|
||||
FlyingMagicWeapon flyingMagicWeapon = new FlyingMagicWeapon(
|
||||
new Mjollnir());
|
||||
flyingMagicWeapon.wield();
|
||||
flyingMagicWeapon.fly();
|
||||
flyingMagicWeapon.swing();
|
||||
flyingMagicWeapon.unwield();
|
||||
|
||||
SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(new Stormbringer());
|
||||
soulEatingMagicWeapon.wield();
|
||||
soulEatingMagicWeapon.swing();
|
||||
soulEatingMagicWeapon.eatSoul();
|
||||
soulEatingMagicWeapon.unwield();
|
||||
}
|
||||
SoulEatingMagicWeapon soulEatingMagicWeapon = new SoulEatingMagicWeapon(
|
||||
new Stormbringer());
|
||||
soulEatingMagicWeapon.wield();
|
||||
soulEatingMagicWeapon.swing();
|
||||
soulEatingMagicWeapon.eatSoul();
|
||||
soulEatingMagicWeapon.unwield();
|
||||
|
||||
}
|
||||
}
|
||||
|
@ -7,31 +7,32 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class BlindingMagicWeapon extends MagicWeapon {
|
||||
|
||||
public BlindingMagicWeapon(BlindingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
public BlindingMagicWeapon(BlindingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
|
||||
@Override
|
||||
public BlindingMagicWeaponImpl getImp() {
|
||||
return (BlindingMagicWeaponImpl) imp;
|
||||
}
|
||||
@Override
|
||||
public BlindingMagicWeaponImpl getImp() {
|
||||
return (BlindingMagicWeaponImpl) imp;
|
||||
}
|
||||
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
|
||||
public void blind() {
|
||||
getImp().blindImp();
|
||||
}
|
||||
|
||||
public void blind() {
|
||||
getImp().blindImp();
|
||||
}
|
||||
}
|
||||
|
@ -7,6 +7,6 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public abstract class BlindingMagicWeaponImpl extends MagicWeaponImpl {
|
||||
|
||||
public abstract void blindImp();
|
||||
public abstract void blindImp();
|
||||
|
||||
}
|
||||
|
@ -7,23 +7,25 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class Excalibur extends BlindingMagicWeaponImpl {
|
||||
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Excalibur");
|
||||
}
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Excalibur");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Excalibur");
|
||||
}
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Excalibur");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Excalibur");
|
||||
}
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Excalibur");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void blindImp() {
|
||||
System.out
|
||||
.println("bright light streams from Excalibur blinding the enemy");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void blindImp() {
|
||||
System.out.println("bright light streams from Excalibur blinding the enemy");
|
||||
}
|
||||
}
|
||||
|
@ -7,31 +7,31 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class FlyingMagicWeapon extends MagicWeapon {
|
||||
|
||||
public FlyingMagicWeapon(FlyingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
public FlyingMagicWeapon(FlyingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
|
||||
public FlyingMagicWeaponImpl getImp() {
|
||||
return (FlyingMagicWeaponImpl) imp;
|
||||
}
|
||||
public FlyingMagicWeaponImpl getImp() {
|
||||
return (FlyingMagicWeaponImpl) imp;
|
||||
}
|
||||
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
|
||||
public void fly() {
|
||||
getImp().flyImp();
|
||||
}
|
||||
public void fly() {
|
||||
getImp().flyImp();
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,6 +7,6 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public abstract class FlyingMagicWeaponImpl extends MagicWeaponImpl {
|
||||
|
||||
public abstract void flyImp();
|
||||
public abstract void flyImp();
|
||||
|
||||
}
|
||||
|
@ -7,19 +7,20 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public abstract class MagicWeapon {
|
||||
|
||||
protected MagicWeaponImpl imp;
|
||||
protected MagicWeaponImpl imp;
|
||||
|
||||
public MagicWeapon(MagicWeaponImpl imp) {
|
||||
this.imp = imp;
|
||||
}
|
||||
public MagicWeapon(MagicWeaponImpl imp) {
|
||||
this.imp = imp;
|
||||
}
|
||||
|
||||
public abstract void wield();
|
||||
public abstract void wield();
|
||||
|
||||
public abstract void swing();
|
||||
public abstract void swing();
|
||||
|
||||
public abstract void unwield();
|
||||
public abstract void unwield();
|
||||
|
||||
public MagicWeaponImpl getImp() {
|
||||
return imp;
|
||||
}
|
||||
|
||||
public MagicWeaponImpl getImp() {
|
||||
return imp;
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,10 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public abstract class MagicWeaponImpl {
|
||||
|
||||
public abstract void wieldImp();
|
||||
public abstract void wieldImp();
|
||||
|
||||
public abstract void swingImp();
|
||||
public abstract void swingImp();
|
||||
|
||||
public abstract void unwieldImp();
|
||||
public abstract void unwieldImp();
|
||||
|
||||
}
|
||||
|
@ -7,23 +7,25 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class Mjollnir extends FlyingMagicWeaponImpl {
|
||||
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Mjollnir");
|
||||
}
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Mjollnir");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Mjollnir");
|
||||
}
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Mjollnir");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Mjollnir");
|
||||
}
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Mjollnir");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void flyImp() {
|
||||
System.out
|
||||
.println("Mjollnir hits the enemy in the air and returns back to the owner's hand");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void flyImp() {
|
||||
System.out.println("Mjollnir hits the enemy in the air and returns back to the owner's hand");
|
||||
}
|
||||
}
|
||||
|
@ -7,32 +7,32 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class SoulEatingMagicWeapon extends MagicWeapon {
|
||||
|
||||
public SoulEatingMagicWeapon(SoulEatingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
public SoulEatingMagicWeapon(SoulEatingMagicWeaponImpl imp) {
|
||||
super(imp);
|
||||
}
|
||||
|
||||
@Override
|
||||
public SoulEatingMagicWeaponImpl getImp() {
|
||||
return (SoulEatingMagicWeaponImpl) imp;
|
||||
}
|
||||
@Override
|
||||
public SoulEatingMagicWeaponImpl getImp() {
|
||||
return (SoulEatingMagicWeaponImpl) imp;
|
||||
}
|
||||
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
@Override
|
||||
public void wield() {
|
||||
getImp().wieldImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
@Override
|
||||
public void swing() {
|
||||
getImp().swingImp();
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
@Override
|
||||
public void unwield() {
|
||||
getImp().unwieldImp();
|
||||
}
|
||||
|
||||
public void eatSoul() {
|
||||
getImp().eatSoulImp();
|
||||
}
|
||||
public void eatSoul() {
|
||||
getImp().eatSoulImp();
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,6 +7,6 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public abstract class SoulEatingMagicWeaponImpl extends MagicWeaponImpl {
|
||||
|
||||
public abstract void eatSoulImp();
|
||||
public abstract void eatSoulImp();
|
||||
|
||||
}
|
||||
|
@ -7,23 +7,24 @@ package com.iluwatar.bridge;
|
||||
*/
|
||||
public class Stormbringer extends SoulEatingMagicWeaponImpl {
|
||||
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Stormbringer");
|
||||
}
|
||||
@Override
|
||||
public void wieldImp() {
|
||||
System.out.println("wielding Stormbringer");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Stormbringer");
|
||||
}
|
||||
@Override
|
||||
public void swingImp() {
|
||||
System.out.println("swinging Stormbringer");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Stormbringer");
|
||||
}
|
||||
@Override
|
||||
public void unwieldImp() {
|
||||
System.out.println("unwielding Stormbringer");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void eatSoulImp() {
|
||||
System.out.println("Stormbringer devours the enemy's soul");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void eatSoulImp() {
|
||||
System.out.println("Stormbringer devours the enemy's soul");
|
||||
}
|
||||
}
|
||||
|
@ -11,9 +11,9 @@ import com.iluwatar.bridge.App;
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
}
|
||||
|
@ -4,9 +4,7 @@ title: Builder
|
||||
folder: builder
|
||||
permalink: /patterns/builder/
|
||||
categories: Creational
|
||||
tags:
|
||||
- Java
|
||||
- Gang Of Four
|
||||
tags: Java
|
||||
---
|
||||
|
||||
**Intent:** Separate the construction of a complex object from its
|
||||
@ -24,7 +22,3 @@ representations.
|
||||
|
||||
* [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html)
|
||||
* [Apache Camel builders](https://github.com/apache/camel/tree/0e195428ee04531be27a0b659005e3aa8d159d23/camel-core/src/main/java/org/apache/camel/builder)
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>builder</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>builder</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -1,55 +1,42 @@
|
||||
package com.iluwatar.builder;
|
||||
|
||||
import com.iluwatar.builder.Hero.HeroBuilder;
|
||||
import com.iluwatar. builder.Hero.HeroBuilder;
|
||||
|
||||
/**
|
||||
*
|
||||
* The intention of the Builder pattern is to find a solution to the telescoping constructor
|
||||
* anti-pattern. The telescoping constructor anti-pattern occurs when the increase of object
|
||||
* constructor parameter combination leads to an exponential list of constructors. Instead of using
|
||||
* numerous constructors, the builder pattern uses another object, a builder, that receives each
|
||||
* initialization parameter step by step and then returns the resulting constructed object at once.
|
||||
* This is the Builder pattern variation as described by Joshua Bloch in
|
||||
* Effective Java 2nd Edition.
|
||||
* <p>
|
||||
* The Builder pattern has another benefit. It can be used for objects that contain flat data (html
|
||||
* code, SQL query, X.509 certificate...), that is to say, data that can't be easily edited. This
|
||||
* type of data cannot be edited step by step and must be edited at once. The best way to construct
|
||||
* such an object is to use a builder class.
|
||||
* <p>
|
||||
* In this example we have the Builder pattern variation as described by Joshua Bloch in Effective
|
||||
* Java 2nd Edition.
|
||||
* <p>
|
||||
* We want to build {@link Hero} objects, but its construction is complex because of the many
|
||||
* parameters needed. To aid the user we introduce {@link HeroBuilder} class. {@link HeroBuilder}
|
||||
* takes the minimum parameters to build {@link Hero} object in its constructor. After that
|
||||
* additional configuration for the {@link Hero} object can be done using the fluent
|
||||
* {@link HeroBuilder} interface. When configuration is ready the build method is called to receive
|
||||
* the final {@link Hero} object.
|
||||
* We want to build {@link Hero} objects, but its construction is complex because of the
|
||||
* many parameters needed. To aid the user we introduce {@link HeroBuilder} class.
|
||||
* {@link HeroBuilder} takes the minimum parameters to build {@link Hero} object in its
|
||||
* constructor. After that additional configuration for the {@link Hero} object can be
|
||||
* done using the fluent {@link HeroBuilder} interface. When configuration is ready the
|
||||
* build method is called to receive the final {@link Hero} object.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
/**
|
||||
* Program entry point
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
Hero mage =
|
||||
new HeroBuilder(Profession.MAGE, "Riobard").withHairColor(HairColor.BLACK)
|
||||
.withWeapon(Weapon.DAGGER).build();
|
||||
System.out.println(mage);
|
||||
Hero mage = new HeroBuilder(Profession.MAGE, "Riobard")
|
||||
.withHairColor(HairColor.BLACK).withWeapon(Weapon.DAGGER)
|
||||
.build();
|
||||
System.out.println(mage);
|
||||
|
||||
Hero warrior =
|
||||
new HeroBuilder(Profession.WARRIOR, "Amberjill").withHairColor(HairColor.BLOND)
|
||||
.withHairType(HairType.LONG_CURLY).withArmor(Armor.CHAIN_MAIL).withWeapon(Weapon.SWORD)
|
||||
.build();
|
||||
System.out.println(warrior);
|
||||
Hero warrior = new HeroBuilder(Profession.WARRIOR, "Amberjill")
|
||||
.withHairColor(HairColor.BLOND)
|
||||
.withHairType(HairType.LONG_CURLY).withArmor(Armor.CHAIN_MAIL)
|
||||
.withWeapon(Weapon.SWORD).build();
|
||||
System.out.println(warrior);
|
||||
|
||||
Hero thief =
|
||||
new HeroBuilder(Profession.THIEF, "Desmond").withHairType(HairType.BALD)
|
||||
.withWeapon(Weapon.BOW).build();
|
||||
System.out.println(thief);
|
||||
Hero thief = new HeroBuilder(Profession.THIEF, "Desmond")
|
||||
.withHairType(HairType.BALD).withWeapon(Weapon.BOW).build();
|
||||
System.out.println(thief);
|
||||
|
||||
}
|
||||
}
|
||||
}
|
||||
|
@ -7,16 +7,16 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public enum Armor {
|
||||
|
||||
CLOTHES("clothes"), LEATHER("leather"), CHAIN_MAIL("chain mail"), PLATE_MAIL("plate mail");
|
||||
CLOTHES("clothes"), LEATHER("leather"), CHAIN_MAIL("chain mail"), PLATE_MAIL("plate mail");
|
||||
|
||||
private String title;
|
||||
private String title;
|
||||
|
||||
Armor(String title) {
|
||||
this.title = title;
|
||||
}
|
||||
Armor(String title) {
|
||||
this.title = title;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return title;
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return title;
|
||||
}
|
||||
}
|
||||
|
@ -7,11 +7,11 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public enum HairColor {
|
||||
|
||||
WHITE, BLOND, RED, BROWN, BLACK;
|
||||
WHITE, BLOND, RED, BROWN, BLACK;
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,17 +7,16 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public enum HairType {
|
||||
|
||||
BALD("bald"), SHORT("short"), CURLY("curly"), LONG_STRAIGHT("long straight"), LONG_CURLY(
|
||||
"long curly");
|
||||
BALD("bald"), SHORT("short"), CURLY("curly"), LONG_STRAIGHT("long straight"), LONG_CURLY("long curly");
|
||||
|
||||
private String title;
|
||||
private String title;
|
||||
|
||||
HairType(String title) {
|
||||
this.title = title;
|
||||
}
|
||||
HairType(String title) {
|
||||
this.title = title;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return title;
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return title;
|
||||
}
|
||||
}
|
||||
|
@ -7,122 +7,123 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public class Hero {
|
||||
|
||||
private final Profession profession;
|
||||
private final String name;
|
||||
private final HairType hairType;
|
||||
private final HairColor hairColor;
|
||||
private final Armor armor;
|
||||
private final Weapon weapon;
|
||||
private final Profession profession;
|
||||
private final String name;
|
||||
private final HairType hairType;
|
||||
private final HairColor hairColor;
|
||||
private final Armor armor;
|
||||
private final Weapon weapon;
|
||||
|
||||
public Profession getProfession() {
|
||||
return profession;
|
||||
}
|
||||
public Profession getProfession() {
|
||||
return profession;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return name;
|
||||
}
|
||||
public String getName() {
|
||||
return name;
|
||||
}
|
||||
|
||||
public HairType getHairType() {
|
||||
return hairType;
|
||||
}
|
||||
public HairType getHairType() {
|
||||
return hairType;
|
||||
}
|
||||
|
||||
public HairColor getHairColor() {
|
||||
return hairColor;
|
||||
}
|
||||
public HairColor getHairColor() {
|
||||
return hairColor;
|
||||
}
|
||||
|
||||
public Armor getArmor() {
|
||||
return armor;
|
||||
}
|
||||
public Armor getArmor() {
|
||||
return armor;
|
||||
}
|
||||
|
||||
public Weapon getWeapon() {
|
||||
return weapon;
|
||||
}
|
||||
public Weapon getWeapon() {
|
||||
return weapon;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
@Override
|
||||
public String toString() {
|
||||
|
||||
StringBuilder sb = new StringBuilder();
|
||||
sb.append("This is a ");
|
||||
sb.append(profession);
|
||||
sb.append(" named ");
|
||||
sb.append(name);
|
||||
if (hairColor != null || hairType != null) {
|
||||
sb.append(" with ");
|
||||
if (hairColor != null) {
|
||||
sb.append(hairColor);
|
||||
sb.append(" ");
|
||||
}
|
||||
if (hairType != null) {
|
||||
sb.append(hairType);
|
||||
sb.append(" ");
|
||||
}
|
||||
sb.append(hairType != HairType.BALD ? "hair" : "head");
|
||||
}
|
||||
if (armor != null) {
|
||||
sb.append(" wearing ");
|
||||
sb.append(armor);
|
||||
}
|
||||
if (weapon != null) {
|
||||
sb.append(" and wielding a ");
|
||||
sb.append(weapon);
|
||||
}
|
||||
sb.append(".");
|
||||
return sb.toString();
|
||||
}
|
||||
StringBuilder sb = new StringBuilder();
|
||||
sb.append("This is a ");
|
||||
sb.append(profession);
|
||||
sb.append(" named ");
|
||||
sb.append(name);
|
||||
if (hairColor != null || hairType != null) {
|
||||
sb.append(" with ");
|
||||
if (hairColor != null) {
|
||||
sb.append(hairColor);
|
||||
sb.append(" ");
|
||||
}
|
||||
if (hairType != null) {
|
||||
sb.append(hairType);
|
||||
sb.append(" ");
|
||||
}
|
||||
sb.append(hairType != HairType.BALD ? "hair" : "head");
|
||||
}
|
||||
if (armor != null) {
|
||||
sb.append(" wearing ");
|
||||
sb.append(armor);
|
||||
}
|
||||
if (weapon != null) {
|
||||
sb.append(" and wielding a ");
|
||||
sb.append(weapon);
|
||||
}
|
||||
sb.append(".");
|
||||
return sb.toString();
|
||||
}
|
||||
|
||||
private Hero(HeroBuilder builder) {
|
||||
this.profession = builder.profession;
|
||||
this.name = builder.name;
|
||||
this.hairColor = builder.hairColor;
|
||||
this.hairType = builder.hairType;
|
||||
this.weapon = builder.weapon;
|
||||
this.armor = builder.armor;
|
||||
}
|
||||
private Hero(HeroBuilder builder) {
|
||||
this.profession = builder.profession;
|
||||
this.name = builder.name;
|
||||
this.hairColor = builder.hairColor;
|
||||
this.hairType = builder.hairType;
|
||||
this.weapon = builder.weapon;
|
||||
this.armor = builder.armor;
|
||||
}
|
||||
|
||||
/**
|
||||
*
|
||||
* The builder class.
|
||||
*
|
||||
*/
|
||||
public static class HeroBuilder {
|
||||
/**
|
||||
*
|
||||
* The builder class.
|
||||
*
|
||||
*/
|
||||
public static class HeroBuilder {
|
||||
|
||||
private final Profession profession;
|
||||
private final String name;
|
||||
private HairType hairType;
|
||||
private HairColor hairColor;
|
||||
private Armor armor;
|
||||
private Weapon weapon;
|
||||
private final Profession profession;
|
||||
private final String name;
|
||||
private HairType hairType;
|
||||
private HairColor hairColor;
|
||||
private Armor armor;
|
||||
private Weapon weapon;
|
||||
|
||||
public HeroBuilder(Profession profession, String name) {
|
||||
if (profession == null || name == null) {
|
||||
throw new IllegalArgumentException("profession and name can not be null");
|
||||
}
|
||||
this.profession = profession;
|
||||
this.name = name;
|
||||
}
|
||||
public HeroBuilder(Profession profession, String name) {
|
||||
if (profession == null || name == null) {
|
||||
throw new IllegalArgumentException(
|
||||
"profession and name can not be null");
|
||||
}
|
||||
this.profession = profession;
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public HeroBuilder withHairType(HairType hairType) {
|
||||
this.hairType = hairType;
|
||||
return this;
|
||||
}
|
||||
public HeroBuilder withHairType(HairType hairType) {
|
||||
this.hairType = hairType;
|
||||
return this;
|
||||
}
|
||||
|
||||
public HeroBuilder withHairColor(HairColor hairColor) {
|
||||
this.hairColor = hairColor;
|
||||
return this;
|
||||
}
|
||||
public HeroBuilder withHairColor(HairColor hairColor) {
|
||||
this.hairColor = hairColor;
|
||||
return this;
|
||||
}
|
||||
|
||||
public HeroBuilder withArmor(Armor armor) {
|
||||
this.armor = armor;
|
||||
return this;
|
||||
}
|
||||
public HeroBuilder withArmor(Armor armor) {
|
||||
this.armor = armor;
|
||||
return this;
|
||||
}
|
||||
|
||||
public HeroBuilder withWeapon(Weapon weapon) {
|
||||
this.weapon = weapon;
|
||||
return this;
|
||||
}
|
||||
public HeroBuilder withWeapon(Weapon weapon) {
|
||||
this.weapon = weapon;
|
||||
return this;
|
||||
}
|
||||
|
||||
public Hero build() {
|
||||
return new Hero(this);
|
||||
}
|
||||
}
|
||||
public Hero build() {
|
||||
return new Hero(this);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,11 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public enum Profession {
|
||||
|
||||
WARRIOR, THIEF, MAGE, PRIEST;
|
||||
WARRIOR, THIEF, MAGE, PRIEST;
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
}
|
||||
|
@ -7,10 +7,11 @@ package com.iluwatar.builder;
|
||||
*/
|
||||
public enum Weapon {
|
||||
|
||||
DAGGER, SWORD, AXE, WARHAMMER, BOW;
|
||||
DAGGER, SWORD, AXE, WARHAMMER, BOW;
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return name().toLowerCase();
|
||||
}
|
||||
}
|
||||
|
@ -2,7 +2,7 @@ package com.iluwatar.builder;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
import com.iluwatar.builder.App;
|
||||
import com.iluwatar. builder.App;
|
||||
|
||||
/**
|
||||
*
|
||||
@ -11,9 +11,9 @@ import com.iluwatar.builder.App;
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
}
|
||||
|
@ -6,7 +6,7 @@
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>business-delegate</artifactId>
|
||||
<dependencies>
|
||||
@ -15,10 +15,5 @@
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
<dependency>
|
||||
<groupId>org.mockito</groupId>
|
||||
<artifactId>mockito-core</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -1,40 +1,35 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
/**
|
||||
* The Business Delegate pattern adds an abstraction layer between the presentation and business
|
||||
* tiers. By using the pattern we gain loose coupling between the tiers. The Business Delegate
|
||||
* encapsulates knowledge about how to locate, connect to, and interact with the business objects
|
||||
* that make up the application.
|
||||
*
|
||||
* <p>Some of the services the Business Delegate uses are instantiated directly, and some can be
|
||||
* retrieved through service lookups. The Business Delegate itself may contain business logic too
|
||||
* potentially tying together multiple service calls, exception handling, retrying etc.
|
||||
*
|
||||
* <p>In this example the client ({@link Client}) utilizes a business delegate (
|
||||
* {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
|
||||
* service and makes the service call.
|
||||
* The Business Delegate pattern adds an abstraction layer between the presentation and business tiers.
|
||||
* By using the pattern we gain loose coupling between the tiers. The Business Delegate encapsulates
|
||||
* knowledge about how to locate, connect to, and interact with the business objects that make up
|
||||
* the application.
|
||||
* <p>
|
||||
* Some of the services the Business Delegate uses are instantiated directly, and some can be retrieved
|
||||
* through service lookups. The Business Delegate itself may contain business logic too potentially tying
|
||||
* together multiple service calls, exception handling, retrying etc.
|
||||
* <p>
|
||||
* In this example the client ({@link Client}) utilizes a business delegate ({@link BusinessDelegate}) to execute a task.
|
||||
* The Business Delegate then selects the appropriate service and makes the service call.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
BusinessDelegate businessDelegate = new BusinessDelegate();
|
||||
businessDelegate.setServiceType(ServiceType.EJB);
|
||||
|
||||
/**
|
||||
* Program entry point.
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
Client client = new Client(businessDelegate);
|
||||
client.doTask();
|
||||
|
||||
BusinessDelegate businessDelegate = new BusinessDelegate();
|
||||
BusinessLookup businessLookup = new BusinessLookup();
|
||||
businessLookup.setEjbService(new EjbService());
|
||||
businessLookup.setJmsService(new JmsService());
|
||||
|
||||
businessDelegate.setLookupService(businessLookup);
|
||||
businessDelegate.setServiceType(ServiceType.EJB);
|
||||
|
||||
Client client = new Client(businessDelegate);
|
||||
client.doTask();
|
||||
|
||||
businessDelegate.setServiceType(ServiceType.JMS);
|
||||
client.doTask();
|
||||
}
|
||||
businessDelegate.setServiceType(ServiceType.JMS);
|
||||
client.doTask();
|
||||
}
|
||||
}
|
||||
|
@ -1,24 +1,22 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
/**
|
||||
*
|
||||
* BusinessDelegate separates the presentation and business tiers
|
||||
*
|
||||
*/
|
||||
public class BusinessDelegate {
|
||||
|
||||
private BusinessLookup lookupService = new BusinessLookup();
|
||||
private BusinessService businessService;
|
||||
private ServiceType serviceType;
|
||||
|
||||
private BusinessLookup lookupService;
|
||||
private BusinessService businessService;
|
||||
private ServiceType serviceType;
|
||||
public void setServiceType(ServiceType serviceType) {
|
||||
this.serviceType = serviceType;
|
||||
}
|
||||
|
||||
public void setLookupService(BusinessLookup businessLookup) {
|
||||
this.lookupService = businessLookup;
|
||||
}
|
||||
|
||||
public void setServiceType(ServiceType serviceType) {
|
||||
this.serviceType = serviceType;
|
||||
}
|
||||
|
||||
public void doTask() {
|
||||
businessService = lookupService.getBusinessService(serviceType);
|
||||
businessService.doProcessing();
|
||||
}
|
||||
public void doTask() {
|
||||
businessService = lookupService.getBusinessService(serviceType);
|
||||
businessService.doProcessing();
|
||||
}
|
||||
}
|
||||
|
@ -1,31 +1,17 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
/**
|
||||
* Class for performing service lookups.
|
||||
*
|
||||
* Class for performing service lookups
|
||||
*
|
||||
*/
|
||||
public class BusinessLookup {
|
||||
|
||||
private EjbService ejbService;
|
||||
|
||||
private JmsService jmsService;
|
||||
|
||||
/**
|
||||
* @param serviceType Type of service instance to be returned.
|
||||
* @return Service instance.
|
||||
*/
|
||||
public BusinessService getBusinessService(ServiceType serviceType) {
|
||||
if (serviceType.equals(ServiceType.EJB)) {
|
||||
return ejbService;
|
||||
} else {
|
||||
return jmsService;
|
||||
}
|
||||
}
|
||||
|
||||
public void setJmsService(JmsService jmsService) {
|
||||
this.jmsService = jmsService;
|
||||
}
|
||||
|
||||
public void setEjbService(EjbService ejbService) {
|
||||
this.ejbService = ejbService;
|
||||
}
|
||||
public BusinessService getBusinessService(ServiceType serviceType) {
|
||||
if (serviceType.equals(ServiceType.EJB)) {
|
||||
return new EjbService();
|
||||
} else {
|
||||
return new JmsService();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
@ -7,5 +7,5 @@ package com.iluwatar.business.delegate;
|
||||
*/
|
||||
public interface BusinessService {
|
||||
|
||||
void doProcessing();
|
||||
void doProcessing();
|
||||
}
|
||||
|
@ -7,13 +7,13 @@ package com.iluwatar.business.delegate;
|
||||
*/
|
||||
public class Client {
|
||||
|
||||
private BusinessDelegate businessDelegate;
|
||||
private BusinessDelegate businessDelegate;
|
||||
|
||||
public Client(BusinessDelegate businessDelegate) {
|
||||
this.businessDelegate = businessDelegate;
|
||||
}
|
||||
public Client(BusinessDelegate businessDelegate) {
|
||||
this.businessDelegate = businessDelegate;
|
||||
}
|
||||
|
||||
public void doTask() {
|
||||
businessDelegate.doTask();
|
||||
}
|
||||
public void doTask() {
|
||||
businessDelegate.doTask();
|
||||
}
|
||||
}
|
||||
|
@ -7,8 +7,8 @@ package com.iluwatar.business.delegate;
|
||||
*/
|
||||
public class EjbService implements BusinessService {
|
||||
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
System.out.println("EjbService is now processing");
|
||||
}
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
System.out.println("EjbService is now processing");
|
||||
}
|
||||
}
|
||||
|
@ -7,8 +7,8 @@ package com.iluwatar.business.delegate;
|
||||
*/
|
||||
public class JmsService implements BusinessService {
|
||||
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
System.out.println("JmsService is now processing");
|
||||
}
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
System.out.println("JmsService is now processing");
|
||||
}
|
||||
}
|
||||
|
@ -6,6 +6,6 @@ package com.iluwatar.business.delegate;
|
||||
*
|
||||
*/
|
||||
public enum ServiceType {
|
||||
|
||||
EJB, JMS;
|
||||
|
||||
EJB, JMS;
|
||||
}
|
||||
|
@ -0,0 +1,19 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
import com.iluwatar.business.delegate.App;
|
||||
|
||||
/**
|
||||
*
|
||||
* Application test
|
||||
*
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
}
|
@ -1,78 +0,0 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
import static org.mockito.Mockito.spy;
|
||||
import static org.mockito.Mockito.times;
|
||||
import static org.mockito.Mockito.verify;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
/**
|
||||
* The Business Delegate pattern adds an abstraction layer between the presentation and business
|
||||
* tiers. By using the pattern we gain loose coupling between the tiers. The Business Delegate
|
||||
* encapsulates knowledge about how to locate, connect to, and interact with the business objects
|
||||
* that make up the application.
|
||||
*
|
||||
* <p>Some of the services the Business Delegate uses are instantiated directly, and some can be
|
||||
* retrieved through service lookups. The Business Delegate itself may contain business logic too
|
||||
* potentially tying together multiple service calls, exception handling, retrying etc.
|
||||
*/
|
||||
public class BusinessDelegateTest {
|
||||
|
||||
private EjbService ejbService;
|
||||
|
||||
private JmsService jmsService;
|
||||
|
||||
private BusinessLookup businessLookup;
|
||||
|
||||
private BusinessDelegate businessDelegate;
|
||||
|
||||
/**
|
||||
* This method sets up the instance variables of this test class. It is executed before the
|
||||
* execution of every test.
|
||||
*/
|
||||
@Before
|
||||
public void setup() {
|
||||
ejbService = spy(new EjbService());
|
||||
jmsService = spy(new JmsService());
|
||||
|
||||
businessLookup = spy(new BusinessLookup());
|
||||
businessLookup.setEjbService(ejbService);
|
||||
businessLookup.setJmsService(jmsService);
|
||||
|
||||
businessDelegate = spy(new BusinessDelegate());
|
||||
businessDelegate.setLookupService(businessLookup);
|
||||
}
|
||||
|
||||
/**
|
||||
* In this example the client ({@link Client}) utilizes a business delegate (
|
||||
* {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
|
||||
* service and makes the service call.
|
||||
*/
|
||||
@Test
|
||||
public void testBusinessDelegate() {
|
||||
|
||||
// setup a client object
|
||||
Client client = new Client(businessDelegate);
|
||||
|
||||
// set the service type
|
||||
businessDelegate.setServiceType(ServiceType.EJB);
|
||||
|
||||
// action
|
||||
client.doTask();
|
||||
|
||||
// verifying that the businessDelegate was used by client during doTask() method.
|
||||
verify(businessDelegate).doTask();
|
||||
verify(ejbService).doProcessing();
|
||||
|
||||
// set the service type
|
||||
businessDelegate.setServiceType(ServiceType.JMS);
|
||||
|
||||
// action
|
||||
client.doTask();
|
||||
|
||||
// verifying that the businessDelegate was used by client during doTask() method.
|
||||
verify(businessDelegate, times(2)).doTask();
|
||||
verify(jmsService).doProcessing();
|
||||
}
|
||||
}
|
1
caching/.gitignore
vendored
1
caching/.gitignore
vendored
@ -1 +0,0 @@
|
||||
/target/
|
Binary file not shown.
Before Width: | Height: | Size: 55 KiB |
@ -1,106 +0,0 @@
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true"
|
||||
realizations="true" associations="true" dependencies="false" nesting-relationships="true">
|
||||
<class id="1" language="java" name="main.java.com.wssia.caching.App" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/App.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="249" y="150"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<class id="2" language="java" name="main.java.com.wssia.caching.AppManager" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/AppManager.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="502" y="163"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<class id="3" language="java" name="main.java.com.wssia.caching.CacheStore" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/CacheStore.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="537" y="436"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<enumeration id="4" language="java" name="main.java.com.wssia.caching.CachingPolicy" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/CachingPolicy.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="789" y="162"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</enumeration>
|
||||
<class id="5" language="java" name="main.java.com.wssia.caching.DBManager" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/DBManager.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="1137" y="134"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<class id="6" language="java" name="main.java.com.wssia.caching.LRUCache" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/LRUCache.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="884" y="435"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<class id="7" language="java" name="main.java.com.wssia.caching.UserAccount" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/main/java/com/wssia/caching/UserAccount.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="1140" y="405"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<class id="8" language="java" name="test.java.com.wssia.caching.AppTest" project="CachingPatterns"
|
||||
file="/CachingPatterns/src/test/java/com/wssia/caching/AppTest.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="251" y="374"/>
|
||||
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</display>
|
||||
</class>
|
||||
<association id="9">
|
||||
<end type="SOURCE" refId="2" navigable="false">
|
||||
<attribute id="10" name="cachingPolicy"/>
|
||||
<multiplicity id="11" minimum="0" maximum="1"/>
|
||||
</end>
|
||||
<end type="TARGET" refId="4" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<association id="12">
|
||||
<end type="SOURCE" refId="8" navigable="false">
|
||||
<attribute id="13" name="app"/>
|
||||
<multiplicity id="14" minimum="0" maximum="1"/>
|
||||
</end>
|
||||
<end type="TARGET" refId="1" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<association id="15">
|
||||
<end type="SOURCE" refId="3" navigable="false">
|
||||
<attribute id="16" name="cache"/>
|
||||
<multiplicity id="17" minimum="0" maximum="1"/>
|
||||
</end>
|
||||
<end type="TARGET" refId="6" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
|
||||
sort-features="false" accessors="true" visibility="true">
|
||||
<attributes public="true" package="true" protected="true" private="true" static="true"/>
|
||||
<operations public="true" package="true" protected="true" private="true" static="true"/>
|
||||
</classifier-display>
|
||||
<association-display labels="true" multiplicity="true"/>
|
||||
</class-diagram>
|
@ -1,24 +0,0 @@
|
||||
---
|
||||
layout: pattern
|
||||
title: Caching
|
||||
folder: caching
|
||||
permalink: /patterns/caching/
|
||||
categories: Other
|
||||
tags:
|
||||
- Java
|
||||
---
|
||||
|
||||
**Intent:** To avoid expensive re-acquisition of resources by not releasing
|
||||
the resources immediately after their use. The resources retain their identity, are kept in some
|
||||
fast-access storage, and are re-used to avoid having to acquire them again.
|
||||
|
||||

|
||||
|
||||
**Applicability:** Use the Caching pattern(s) when
|
||||
|
||||
* Repetitious acquisition, initialization, and release of the same resource causes unnecessary performance overhead.
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained)
|
||||
* [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177)
|
@ -1,51 +0,0 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>caching</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
<dependency>
|
||||
<groupId>org.mongodb</groupId>
|
||||
<artifactId>mongodb-driver</artifactId>
|
||||
<version>3.0.4</version>
|
||||
</dependency>
|
||||
<dependency>
|
||||
<groupId>org.mongodb</groupId>
|
||||
<artifactId>mongodb-driver-core</artifactId>
|
||||
<version>3.0.4</version>
|
||||
</dependency>
|
||||
<dependency>
|
||||
<groupId>org.mongodb</groupId>
|
||||
<artifactId>bson</artifactId>
|
||||
<version>3.0.4</version>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<!--
|
||||
Due to the use of MongoDB in the test of this pattern, TRAVIS and/or MAVEN might fail if the DB connection is
|
||||
not open for the JUnit test. To avoid disrupting the compilation process, the surefire plug-in was used
|
||||
to SKIP the running of the JUnit tests for this pattern. To ACTIVATE the running of the tests, change the
|
||||
skipTests (below) flag to 'false' and vice-versa.
|
||||
-->
|
||||
<build>
|
||||
<plugins>
|
||||
<plugin>
|
||||
<groupId>org.apache.maven.plugins</groupId>
|
||||
<artifactId>maven-surefire-plugin</artifactId>
|
||||
<version>2.19</version>
|
||||
<configuration>
|
||||
<skipTests>false</skipTests>
|
||||
</configuration>
|
||||
</plugin>
|
||||
</plugins>
|
||||
</build>
|
||||
</project>
|
@ -1,117 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
/**
|
||||
*
|
||||
* The Caching pattern describes how to avoid expensive re-acquisition of resources by not releasing
|
||||
* the resources immediately after their use. The resources retain their identity, are kept in some
|
||||
* fast-access storage, and are re-used to avoid having to acquire them again. There are three main
|
||||
* caching strategies/techniques in this pattern; each with their own pros and cons. They are:
|
||||
* <code>write-through</code> which writes data to the cache and DB in a single transaction,
|
||||
* <code>write-around</code> which writes data immediately into the DB instead of the cache, and
|
||||
* <code>write-behind</code> which writes data into the cache initially whilst the data is only
|
||||
* written into the DB when the cache is full. The <code>read-through</code> strategy is also
|
||||
* included in the mentioned three strategies -- returns data from the cache to the caller <b>if</b>
|
||||
* it exists <b>else</b> queries from DB and stores it into the cache for future use. These
|
||||
* strategies determine when the data in the cache should be written back to the backing store (i.e.
|
||||
* Database) and help keep both data sources synchronized/up-to-date. This pattern can improve
|
||||
* performance and also helps to maintain consistency between data held in the cache and the data in
|
||||
* the underlying data store.
|
||||
* <p>
|
||||
* In this example, the user account ({@link UserAccount}) entity is used as the underlying
|
||||
* application data. The cache itself is implemented as an internal (Java) data structure. It adopts
|
||||
* a Least-Recently-Used (LRU) strategy for evicting data from itself when its full. The three
|
||||
* strategies are individually tested. The testing of the cache is restricted towards saving and
|
||||
* querying of user accounts from the underlying data store ( {@link DBManager}). The main class (
|
||||
* {@link App} is not aware of the underlying mechanics of the application (i.e. save and query) and
|
||||
* whether the data is coming from the cache or the DB (i.e. separation of concern). The AppManager
|
||||
* ({@link AppManager}) handles the transaction of data to-and-from the underlying data store
|
||||
* (depending on the preferred caching policy/strategy).
|
||||
*
|
||||
* <i>App --> AppManager --> CacheStore/LRUCache/CachingPolicy --> DBManager</i>
|
||||
* </p>
|
||||
*
|
||||
* @see CacheStore
|
||||
* @See LRUCache
|
||||
* @see CachingPolicy
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
AppManager.initDB(false); // VirtualDB (instead of MongoDB) was used in running the JUnit tests
|
||||
// and the App class to avoid Maven compilation errors. Set flag to
|
||||
// true to run the tests with MongoDB (provided that MongoDB is
|
||||
// installed and socket connection is open).
|
||||
AppManager.initCacheCapacity(3);
|
||||
App app = new App();
|
||||
app.useReadAndWriteThroughStrategy();
|
||||
app.useReadThroughAndWriteAroundStrategy();
|
||||
app.useReadThroughAndWriteBehindStrategy();
|
||||
}
|
||||
|
||||
/**
|
||||
* Read-through and write-through
|
||||
*/
|
||||
public void useReadAndWriteThroughStrategy() {
|
||||
System.out.println("# CachingPolicy.THROUGH");
|
||||
AppManager.initCachingPolicy(CachingPolicy.THROUGH);
|
||||
|
||||
UserAccount userAccount1 = new UserAccount("001", "John", "He is a boy.");
|
||||
|
||||
AppManager.save(userAccount1);
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount1 = AppManager.find("001");
|
||||
userAccount1 = AppManager.find("001");
|
||||
}
|
||||
|
||||
/**
|
||||
* Read-through and write-around
|
||||
*/
|
||||
public void useReadThroughAndWriteAroundStrategy() {
|
||||
System.out.println("# CachingPolicy.AROUND");
|
||||
AppManager.initCachingPolicy(CachingPolicy.AROUND);
|
||||
|
||||
UserAccount userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
|
||||
|
||||
AppManager.save(userAccount2);
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount2 = AppManager.find("002");
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount2 = AppManager.find("002");
|
||||
userAccount2.setUserName("Jane G.");
|
||||
AppManager.save(userAccount2);
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount2 = AppManager.find("002");
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount2 = AppManager.find("002");
|
||||
}
|
||||
|
||||
/**
|
||||
* Read-through and write-behind
|
||||
*/
|
||||
public void useReadThroughAndWriteBehindStrategy() {
|
||||
System.out.println("# CachingPolicy.BEHIND");
|
||||
AppManager.initCachingPolicy(CachingPolicy.BEHIND);
|
||||
|
||||
UserAccount userAccount3 = new UserAccount("003", "Adam", "He likes food.");
|
||||
UserAccount userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
|
||||
UserAccount userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
|
||||
|
||||
AppManager.save(userAccount3);
|
||||
AppManager.save(userAccount4);
|
||||
AppManager.save(userAccount5);
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount3 = AppManager.find("003");
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
UserAccount userAccount6 = new UserAccount("006", "Yasha", "She is an only child.");
|
||||
AppManager.save(userAccount6);
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
userAccount4 = AppManager.find("004");
|
||||
System.out.println(AppManager.printCacheContent());
|
||||
}
|
||||
}
|
@ -1,75 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
import java.text.ParseException;
|
||||
|
||||
/**
|
||||
*
|
||||
* AppManager helps to bridge the gap in communication between the main class and the application's
|
||||
* back-end. DB connection is initialized through this class. The chosen caching strategy/policy is
|
||||
* also initialized here. Before the cache can be used, the size of the cache has to be set.
|
||||
* Depending on the chosen caching policy, AppManager will call the appropriate function in the
|
||||
* CacheStore class.
|
||||
*
|
||||
*/
|
||||
public class AppManager {
|
||||
|
||||
private static CachingPolicy cachingPolicy;
|
||||
|
||||
/**
|
||||
*
|
||||
* Developer/Tester is able to choose whether the application should use MongoDB as its underlying
|
||||
* data storage or a simple Java data structure to (temporarily) store the data/objects during
|
||||
* runtime.
|
||||
*/
|
||||
public static void initDB(boolean useMongoDB) {
|
||||
if (useMongoDB) {
|
||||
try {
|
||||
DBManager.connect();
|
||||
} catch (ParseException e) {
|
||||
e.printStackTrace();
|
||||
}
|
||||
} else {
|
||||
DBManager.createVirtualDB();
|
||||
}
|
||||
}
|
||||
|
||||
public static void initCachingPolicy(CachingPolicy policy) {
|
||||
cachingPolicy = policy;
|
||||
if (cachingPolicy == CachingPolicy.BEHIND) {
|
||||
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
|
||||
@Override
|
||||
public void run() {
|
||||
CacheStore.flushCache();
|
||||
}
|
||||
}));
|
||||
}
|
||||
CacheStore.clearCache();
|
||||
}
|
||||
|
||||
public static void initCacheCapacity(int capacity) {
|
||||
CacheStore.initCapacity(capacity);
|
||||
}
|
||||
|
||||
public static UserAccount find(String userID) {
|
||||
if (cachingPolicy == CachingPolicy.THROUGH || cachingPolicy == CachingPolicy.AROUND) {
|
||||
return CacheStore.readThrough(userID);
|
||||
} else if (cachingPolicy == CachingPolicy.BEHIND) {
|
||||
return CacheStore.readThroughWithWriteBackPolicy(userID);
|
||||
}
|
||||
return null;
|
||||
}
|
||||
|
||||
public static void save(UserAccount userAccount) {
|
||||
if (cachingPolicy == CachingPolicy.THROUGH) {
|
||||
CacheStore.writeThrough(userAccount);
|
||||
} else if (cachingPolicy == CachingPolicy.AROUND) {
|
||||
CacheStore.writeAround(userAccount);
|
||||
} else if (cachingPolicy == CachingPolicy.BEHIND) {
|
||||
CacheStore.writeBehind(userAccount);
|
||||
}
|
||||
}
|
||||
|
||||
public static String printCacheContent() {
|
||||
return CacheStore.print();
|
||||
}
|
||||
}
|
@ -1,104 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
import java.util.ArrayList;
|
||||
|
||||
/**
|
||||
*
|
||||
* The caching strategies are implemented in this class.
|
||||
*
|
||||
*/
|
||||
public class CacheStore {
|
||||
|
||||
static LRUCache cache = null;
|
||||
|
||||
public static void initCapacity(int capacity) {
|
||||
if (null == cache)
|
||||
cache = new LRUCache(capacity);
|
||||
else
|
||||
cache.setCapacity(capacity);
|
||||
}
|
||||
|
||||
public static UserAccount readThrough(String userID) {
|
||||
if (cache.contains(userID)) {
|
||||
System.out.println("# Cache Hit!");
|
||||
return cache.get(userID);
|
||||
}
|
||||
System.out.println("# Cache Miss!");
|
||||
UserAccount userAccount = DBManager.readFromDB(userID);
|
||||
cache.set(userID, userAccount);
|
||||
return userAccount;
|
||||
}
|
||||
|
||||
public static void writeThrough(UserAccount userAccount) {
|
||||
if (cache.contains(userAccount.getUserID())) {
|
||||
DBManager.updateDB(userAccount);
|
||||
} else {
|
||||
DBManager.writeToDB(userAccount);
|
||||
}
|
||||
cache.set(userAccount.getUserID(), userAccount);
|
||||
}
|
||||
|
||||
public static void writeAround(UserAccount userAccount) {
|
||||
if (cache.contains(userAccount.getUserID())) {
|
||||
DBManager.updateDB(userAccount);
|
||||
cache.invalidate(userAccount.getUserID()); // Cache data has been updated -- remove older
|
||||
// version from cache.
|
||||
} else {
|
||||
DBManager.writeToDB(userAccount);
|
||||
}
|
||||
}
|
||||
|
||||
public static UserAccount readThroughWithWriteBackPolicy(String userID) {
|
||||
if (cache.contains(userID)) {
|
||||
System.out.println("# Cache Hit!");
|
||||
return cache.get(userID);
|
||||
}
|
||||
System.out.println("# Cache Miss!");
|
||||
UserAccount userAccount = DBManager.readFromDB(userID);
|
||||
if (cache.isFull()) {
|
||||
System.out.println("# Cache is FULL! Writing LRU data to DB...");
|
||||
UserAccount toBeWrittenToDB = cache.getLRUData();
|
||||
DBManager.upsertDB(toBeWrittenToDB);
|
||||
}
|
||||
cache.set(userID, userAccount);
|
||||
return userAccount;
|
||||
}
|
||||
|
||||
public static void writeBehind(UserAccount userAccount) {
|
||||
if (cache.isFull() && !cache.contains(userAccount.getUserID())) {
|
||||
System.out.println("# Cache is FULL! Writing LRU data to DB...");
|
||||
UserAccount toBeWrittenToDB = cache.getLRUData();
|
||||
DBManager.upsertDB(toBeWrittenToDB);
|
||||
}
|
||||
cache.set(userAccount.getUserID(), userAccount);
|
||||
}
|
||||
|
||||
public static void clearCache() {
|
||||
if (null != cache)
|
||||
cache.clear();
|
||||
}
|
||||
|
||||
/**
|
||||
* Writes remaining content in the cache into the DB.
|
||||
*/
|
||||
public static void flushCache() {
|
||||
System.out.println("# flushCache...");
|
||||
if (null == cache)
|
||||
return;
|
||||
ArrayList<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
|
||||
for (UserAccount userAccount : listOfUserAccounts) {
|
||||
DBManager.upsertDB(userAccount);
|
||||
}
|
||||
}
|
||||
|
||||
public static String print() {
|
||||
ArrayList<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
|
||||
StringBuilder sb = new StringBuilder();
|
||||
sb.append("\n--CACHE CONTENT--\n");
|
||||
for (UserAccount userAccount : listOfUserAccounts) {
|
||||
sb.append(userAccount.toString() + "\n");
|
||||
}
|
||||
sb.append("----\n");
|
||||
return sb.toString();
|
||||
}
|
||||
}
|
@ -1,20 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
/**
|
||||
*
|
||||
* Enum class containing the three caching strategies implemented in the pattern.
|
||||
*
|
||||
*/
|
||||
public enum CachingPolicy {
|
||||
THROUGH("through"), AROUND("around"), BEHIND("behind");
|
||||
|
||||
private String policy;
|
||||
|
||||
private CachingPolicy(String policy) {
|
||||
this.policy = policy;
|
||||
}
|
||||
|
||||
public String getPolicy() {
|
||||
return policy;
|
||||
}
|
||||
}
|
@ -1,123 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
import java.text.ParseException;
|
||||
import java.util.HashMap;
|
||||
|
||||
import org.bson.Document;
|
||||
|
||||
import com.mongodb.MongoClient;
|
||||
import com.mongodb.client.FindIterable;
|
||||
import com.mongodb.client.MongoDatabase;
|
||||
import com.mongodb.client.model.UpdateOptions;
|
||||
|
||||
/**
|
||||
*
|
||||
* <p>DBManager handles the communication with the underlying data store i.e. Database. It contains the
|
||||
* implemented methods for querying, inserting, and updating data. MongoDB was used as the database
|
||||
* for the application.</p>
|
||||
*
|
||||
* <p>Developer/Tester is able to choose whether the application should use MongoDB as its underlying
|
||||
* data storage (connect()) or a simple Java data structure to (temporarily) store the data/objects
|
||||
* during runtime (createVirtualDB()).</p>
|
||||
*
|
||||
*/
|
||||
public class DBManager {
|
||||
|
||||
private static MongoClient mongoClient;
|
||||
private static MongoDatabase db;
|
||||
private static boolean useMongoDB;
|
||||
|
||||
private static HashMap<String, UserAccount> virtualDB;
|
||||
|
||||
public static void createVirtualDB() {
|
||||
useMongoDB = false;
|
||||
virtualDB = new HashMap<String, UserAccount>();
|
||||
}
|
||||
|
||||
public static void connect() throws ParseException {
|
||||
useMongoDB = true;
|
||||
mongoClient = new MongoClient();
|
||||
db = mongoClient.getDatabase("test");
|
||||
}
|
||||
|
||||
public static UserAccount readFromDB(String userID) {
|
||||
if (!useMongoDB) {
|
||||
if (virtualDB.containsKey(userID))
|
||||
return virtualDB.get(userID);
|
||||
return null;
|
||||
}
|
||||
if (null == db) {
|
||||
try {
|
||||
connect();
|
||||
} catch (ParseException e) {
|
||||
e.printStackTrace();
|
||||
}
|
||||
}
|
||||
FindIterable<Document> iterable =
|
||||
db.getCollection("user_accounts").find(new Document("userID", userID));
|
||||
if (iterable == null)
|
||||
return null;
|
||||
Document doc = iterable.first();
|
||||
UserAccount userAccount =
|
||||
new UserAccount(userID, doc.getString("userName"), doc.getString("additionalInfo"));
|
||||
return userAccount;
|
||||
}
|
||||
|
||||
public static void writeToDB(UserAccount userAccount) {
|
||||
if (!useMongoDB) {
|
||||
virtualDB.put(userAccount.getUserID(), userAccount);
|
||||
return;
|
||||
}
|
||||
if (null == db) {
|
||||
try {
|
||||
connect();
|
||||
} catch (ParseException e) {
|
||||
e.printStackTrace();
|
||||
}
|
||||
}
|
||||
db.getCollection("user_accounts").insertOne(
|
||||
new Document("userID", userAccount.getUserID()).append("userName",
|
||||
userAccount.getUserName()).append("additionalInfo", userAccount.getAdditionalInfo()));
|
||||
}
|
||||
|
||||
public static void updateDB(UserAccount userAccount) {
|
||||
if (!useMongoDB) {
|
||||
virtualDB.put(userAccount.getUserID(), userAccount);
|
||||
return;
|
||||
}
|
||||
if (null == db) {
|
||||
try {
|
||||
connect();
|
||||
} catch (ParseException e) {
|
||||
e.printStackTrace();
|
||||
}
|
||||
}
|
||||
db.getCollection("user_accounts").updateOne(
|
||||
new Document("userID", userAccount.getUserID()),
|
||||
new Document("$set", new Document("userName", userAccount.getUserName()).append(
|
||||
"additionalInfo", userAccount.getAdditionalInfo())));
|
||||
}
|
||||
|
||||
/**
|
||||
*
|
||||
* Insert data into DB if it does not exist. Else, update it.
|
||||
*/
|
||||
public static void upsertDB(UserAccount userAccount) {
|
||||
if (!useMongoDB) {
|
||||
virtualDB.put(userAccount.getUserID(), userAccount);
|
||||
return;
|
||||
}
|
||||
if (null == db) {
|
||||
try {
|
||||
connect();
|
||||
} catch (ParseException e) {
|
||||
e.printStackTrace();
|
||||
}
|
||||
}
|
||||
db.getCollection("user_accounts").updateOne(
|
||||
new Document("userID", userAccount.getUserID()),
|
||||
new Document("$set", new Document("userID", userAccount.getUserID()).append("userName",
|
||||
userAccount.getUserName()).append("additionalInfo", userAccount.getAdditionalInfo())),
|
||||
new UpdateOptions().upsert(true));
|
||||
}
|
||||
}
|
@ -1,146 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.HashMap;
|
||||
|
||||
/**
|
||||
*
|
||||
* Data structure/implementation of the application's cache. The data structure consists of a hash
|
||||
* table attached with a doubly linked-list. The linked-list helps in capturing and maintaining the
|
||||
* LRU data in the cache. When a data is queried (from the cache), added (to the cache), or updated,
|
||||
* the data is moved to the front of the list to depict itself as the most-recently-used data. The
|
||||
* LRU data is always at the end of the list.
|
||||
*
|
||||
*/
|
||||
public class LRUCache {
|
||||
|
||||
class Node {
|
||||
String userID;
|
||||
UserAccount userAccount;
|
||||
Node previous;
|
||||
Node next;
|
||||
|
||||
public Node(String userID, UserAccount userAccount) {
|
||||
this.userID = userID;
|
||||
this.userAccount = userAccount;
|
||||
}
|
||||
}
|
||||
|
||||
int capacity;
|
||||
HashMap<String, Node> cache = new HashMap<String, Node>();
|
||||
Node head = null;
|
||||
Node end = null;
|
||||
|
||||
public LRUCache(int capacity) {
|
||||
this.capacity = capacity;
|
||||
}
|
||||
|
||||
public UserAccount get(String userID) {
|
||||
if (cache.containsKey(userID)) {
|
||||
Node node = cache.get(userID);
|
||||
remove(node);
|
||||
setHead(node);
|
||||
return node.userAccount;
|
||||
}
|
||||
return null;
|
||||
}
|
||||
|
||||
/**
|
||||
*
|
||||
* Remove node from linked list.
|
||||
*/
|
||||
public void remove(Node node) {
|
||||
if (node.previous != null) {
|
||||
node.previous.next = node.next;
|
||||
} else {
|
||||
head = node.next;
|
||||
}
|
||||
if (node.next != null) {
|
||||
node.next.previous = node.previous;
|
||||
} else {
|
||||
end = node.previous;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
*
|
||||
* Move node to the front of the list.
|
||||
*/
|
||||
public void setHead(Node node) {
|
||||
node.next = head;
|
||||
node.previous = null;
|
||||
if (head != null)
|
||||
head.previous = node;
|
||||
head = node;
|
||||
if (end == null)
|
||||
end = head;
|
||||
}
|
||||
|
||||
public void set(String userID, UserAccount userAccount) {
|
||||
if (cache.containsKey(userID)) {
|
||||
Node old = cache.get(userID);
|
||||
old.userAccount = userAccount;
|
||||
remove(old);
|
||||
setHead(old);
|
||||
} else {
|
||||
Node newNode = new Node(userID, userAccount);
|
||||
if (cache.size() >= capacity) {
|
||||
System.out.println("# Cache is FULL! Removing " + end.userID + " from cache...");
|
||||
cache.remove(end.userID); // remove LRU data from cache.
|
||||
remove(end);
|
||||
setHead(newNode);
|
||||
} else {
|
||||
setHead(newNode);
|
||||
}
|
||||
cache.put(userID, newNode);
|
||||
}
|
||||
}
|
||||
|
||||
public boolean contains(String userID) {
|
||||
return cache.containsKey(userID);
|
||||
}
|
||||
|
||||
public void invalidate(String userID) {
|
||||
System.out.println("# " + userID + " has been updated! Removing older version from cache...");
|
||||
Node toBeRemoved = cache.get(userID);
|
||||
remove(toBeRemoved);
|
||||
cache.remove(userID);
|
||||
}
|
||||
|
||||
public boolean isFull() {
|
||||
return cache.size() >= capacity;
|
||||
}
|
||||
|
||||
public UserAccount getLRUData() {
|
||||
return end.userAccount;
|
||||
}
|
||||
|
||||
public void clear() {
|
||||
head = null;
|
||||
end = null;
|
||||
cache.clear();
|
||||
}
|
||||
|
||||
/**
|
||||
*
|
||||
* Returns cache data in list form.
|
||||
*/
|
||||
public ArrayList<UserAccount> getCacheDataInListForm() {
|
||||
ArrayList<UserAccount> listOfCacheData = new ArrayList<UserAccount>();
|
||||
Node temp = head;
|
||||
while (temp != null) {
|
||||
listOfCacheData.add(temp.userAccount);
|
||||
temp = temp.next;
|
||||
}
|
||||
return listOfCacheData;
|
||||
}
|
||||
|
||||
public void setCapacity(int newCapacity) {
|
||||
if (capacity > newCapacity) {
|
||||
clear(); // Behavior can be modified to accommodate for decrease in cache size. For now, we'll
|
||||
// just clear the cache.
|
||||
} else {
|
||||
this.capacity = newCapacity;
|
||||
}
|
||||
}
|
||||
}
|
@ -1,47 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
/**
|
||||
*
|
||||
* Entity class (stored in cache and DB) used in the application.
|
||||
*
|
||||
*/
|
||||
public class UserAccount {
|
||||
private String userID;
|
||||
private String userName;
|
||||
private String additionalInfo;
|
||||
|
||||
public UserAccount(String userID, String userName, String additionalInfo) {
|
||||
this.userID = userID;
|
||||
this.userName = userName;
|
||||
this.additionalInfo = additionalInfo;
|
||||
}
|
||||
|
||||
public String getUserID() {
|
||||
return userID;
|
||||
}
|
||||
|
||||
public void setUserID(String userID) {
|
||||
this.userID = userID;
|
||||
}
|
||||
|
||||
public String getUserName() {
|
||||
return userName;
|
||||
}
|
||||
|
||||
public void setUserName(String userName) {
|
||||
this.userName = userName;
|
||||
}
|
||||
|
||||
public String getAdditionalInfo() {
|
||||
return additionalInfo;
|
||||
}
|
||||
|
||||
public void setAdditionalInfo(String additionalInfo) {
|
||||
this.additionalInfo = additionalInfo;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return userID + ", " + userName + ", " + additionalInfo;
|
||||
}
|
||||
}
|
@ -1,41 +0,0 @@
|
||||
package com.iluwatar.caching;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
/**
|
||||
*
|
||||
* Application test
|
||||
*
|
||||
*/
|
||||
public class AppTest {
|
||||
App app;
|
||||
|
||||
/**
|
||||
* Setup of application test includes: initializing DB connection and cache size/capacity.
|
||||
*/
|
||||
@Before
|
||||
public void setUp() {
|
||||
AppManager.initDB(false); // VirtualDB (instead of MongoDB) was used in running the JUnit tests
|
||||
// to avoid Maven compilation errors. Set flag to true to run the
|
||||
// tests with MongoDB (provided that MongoDB is installed and socket
|
||||
// connection is open).
|
||||
AppManager.initCacheCapacity(3);
|
||||
app = new App();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testReadAndWriteThroughStrategy() {
|
||||
app.useReadAndWriteThroughStrategy();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testReadThroughAndWriteAroundStrategy() {
|
||||
app.useReadThroughAndWriteAroundStrategy();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testReadThroughAndWriteBehindStrategy() {
|
||||
app.useReadThroughAndWriteBehindStrategy();
|
||||
}
|
||||
}
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>callback</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>callback</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -2,21 +2,20 @@ package com.iluwatar.callback;
|
||||
|
||||
/**
|
||||
*
|
||||
* Callback pattern is more native for functional languages where functions are treated as
|
||||
* first-class citizens. Prior to Java 8 callbacks can be simulated using simple (alike command)
|
||||
* interfaces.
|
||||
* Callback pattern is more native for functional languages where functions are treated as first-class citizens.
|
||||
* Prior to Java 8 callbacks can be simulated using simple (alike command) interfaces.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
public static void main(String[] args) {
|
||||
Task task = new SimpleTask();
|
||||
Callback callback = new Callback() {
|
||||
@Override
|
||||
public void call() {
|
||||
System.out.println("I'm done now.");
|
||||
}
|
||||
};
|
||||
task.executeWith(callback);
|
||||
}
|
||||
public static void main(String[] args) {
|
||||
Task task = new SimpleTask();
|
||||
Callback callback = new Callback() {
|
||||
@Override
|
||||
public void call() {
|
||||
System.out.println("I'm done now.");
|
||||
}
|
||||
};
|
||||
task.executeWith(callback);
|
||||
}
|
||||
}
|
||||
|
@ -7,5 +7,5 @@ package com.iluwatar.callback;
|
||||
*/
|
||||
public interface Callback {
|
||||
|
||||
public void call();
|
||||
public void call();
|
||||
}
|
||||
|
@ -7,8 +7,9 @@ package com.iluwatar.callback;
|
||||
*/
|
||||
public class SimpleTask extends Task {
|
||||
|
||||
@Override
|
||||
public void execute() {
|
||||
System.out.println("Perform some important activity and after call the callback method.");
|
||||
}
|
||||
@Override
|
||||
public void execute() {
|
||||
System.out.println("Perform some important activity.");
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,12 +7,12 @@ package com.iluwatar.callback;
|
||||
*/
|
||||
public abstract class Task {
|
||||
|
||||
public final void executeWith(Callback callback) {
|
||||
execute();
|
||||
if (callback != null) {
|
||||
callback.call();
|
||||
}
|
||||
}
|
||||
public final void executeWith(Callback callback) {
|
||||
execute();
|
||||
if (callback != null) {
|
||||
callback.call();
|
||||
}
|
||||
}
|
||||
|
||||
public abstract void execute();
|
||||
public abstract void execute();
|
||||
}
|
||||
|
@ -2,38 +2,18 @@ package com.iluwatar.callback;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
import static org.junit.Assert.assertEquals;
|
||||
import com.iluwatar.callback.App;
|
||||
|
||||
/**
|
||||
* Add a field as a counter. Every time the callback method is called increment this field. Unit
|
||||
* test checks that the field is being incremented.
|
||||
*
|
||||
* Application test
|
||||
*
|
||||
* Could be done with mock objects as well where the call method call is verified.
|
||||
*/
|
||||
public class AppTest {
|
||||
|
||||
private Integer callingCount = 0;
|
||||
|
||||
@Test
|
||||
public void test() {
|
||||
Callback callback = new Callback() {
|
||||
@Override
|
||||
public void call() {
|
||||
callingCount++;
|
||||
}
|
||||
};
|
||||
|
||||
Task task = new SimpleTask();
|
||||
|
||||
assertEquals("Initial calling count of 0", new Integer(0), callingCount);
|
||||
|
||||
task.executeWith(callback);
|
||||
|
||||
assertEquals("Callback called once", new Integer(1), callingCount);
|
||||
|
||||
task.executeWith(callback);
|
||||
|
||||
assertEquals("Callback called twice", new Integer(2), callingCount);
|
||||
|
||||
}
|
||||
@Test
|
||||
public void test() {
|
||||
String[] args = {};
|
||||
App.main(args);
|
||||
}
|
||||
}
|
||||
|
@ -4,9 +4,7 @@ title: Chain of responsibility
|
||||
folder: chain
|
||||
permalink: /patterns/chain/
|
||||
categories: Behavioral
|
||||
tags:
|
||||
- Java
|
||||
- Gang Of Four
|
||||
tags: Java
|
||||
---
|
||||
|
||||
**Intent:** Avoid coupling the sender of a request to its receiver by giving
|
||||
@ -25,7 +23,3 @@ objects and pass the request along the chain until an object handles it.
|
||||
|
||||
* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
|
||||
* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)
|
||||
|
||||
**Credits**
|
||||
|
||||
* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
|
||||
|
@ -1,18 +1,19 @@
|
||||
<?xml version="1.0"?>
|
||||
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
|
||||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.8.0</version>
|
||||
</parent>
|
||||
<artifactId>chain</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
<project
|
||||
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
|
||||
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|
||||
<modelVersion>4.0.0</modelVersion>
|
||||
<parent>
|
||||
<groupId>com.iluwatar</groupId>
|
||||
<artifactId>java-design-patterns</artifactId>
|
||||
<version>1.6.0</version>
|
||||
</parent>
|
||||
<artifactId>chain</artifactId>
|
||||
<dependencies>
|
||||
<dependency>
|
||||
<groupId>junit</groupId>
|
||||
<artifactId>junit</artifactId>
|
||||
<scope>test</scope>
|
||||
</dependency>
|
||||
</dependencies>
|
||||
</project>
|
||||
|
@ -2,30 +2,25 @@ package com.iluwatar.chain;
|
||||
|
||||
/**
|
||||
*
|
||||
* The Chain of Responsibility pattern is a design pattern consisting of command objects and a
|
||||
* series of processing objects. Each processing object contains logic that defines the types of
|
||||
* command objects that it can handle; the rest are passed to the next processing object in the
|
||||
* chain. A mechanism also exists for adding new processing objects to the end of this chain.
|
||||
* <p>
|
||||
* In this example we organize the request handlers ({@link RequestHandler}) into a chain where each
|
||||
* handler has a chance to act on the request on its turn. Here the king ({@link OrcKing}) makes
|
||||
* requests and the military orcs ({@link OrcCommander}, {@link OrcOfficer}, {@link OrcSoldier})
|
||||
* form the handler chain.
|
||||
* Chain of Responsibility organizes request handlers ({@link RequestHandler}) into a
|
||||
* chain where each handler has a chance to act on the request on its turn. In
|
||||
* this example the king ({@link OrcKing}) makes requests and the military orcs
|
||||
* ({@link OrcCommander}, {@link OrcOfficer}, {@link OrcSoldier}) form the handler chain.
|
||||
*
|
||||
*/
|
||||
public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
/**
|
||||
* Program entry point
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
OrcKing king = new OrcKing();
|
||||
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
|
||||
king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
|
||||
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
|
||||
OrcKing king = new OrcKing();
|
||||
king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
|
||||
king.makeRequest(new Request(RequestType.TORTURE_PRISONER,
|
||||
"torture prisoner"));
|
||||
king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
|
||||
|
||||
}
|
||||
}
|
||||
}
|
||||
|
@ -7,21 +7,21 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public class OrcCommander extends RequestHandler {
|
||||
|
||||
public OrcCommander(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
public OrcCommander(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc commander";
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc commander";
|
||||
}
|
||||
}
|
||||
|
@ -7,18 +7,18 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public class OrcKing {
|
||||
|
||||
RequestHandler chain;
|
||||
RequestHandler chain;
|
||||
|
||||
public OrcKing() {
|
||||
buildChain();
|
||||
}
|
||||
public OrcKing() {
|
||||
buildChain();
|
||||
}
|
||||
|
||||
private void buildChain() {
|
||||
chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
|
||||
}
|
||||
private void buildChain() {
|
||||
chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
|
||||
}
|
||||
|
||||
public void makeRequest(Request req) {
|
||||
chain.handleRequest(req);
|
||||
}
|
||||
public void makeRequest(Request req) {
|
||||
chain.handleRequest(req);
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,22 +7,22 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public class OrcOfficer extends RequestHandler {
|
||||
|
||||
public OrcOfficer(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
public OrcOfficer(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.TORTURE_PRISONER)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.TORTURE_PRISONER)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc officer";
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc officer";
|
||||
}
|
||||
|
||||
}
|
||||
|
@ -7,21 +7,21 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public class OrcSoldier extends RequestHandler {
|
||||
|
||||
public OrcSoldier(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
public OrcSoldier(RequestHandler handler) {
|
||||
super(handler);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.COLLECT_TAX)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
@Override
|
||||
public void handleRequest(Request req) {
|
||||
if (req.getRequestType().equals(RequestType.COLLECT_TAX)) {
|
||||
printHandling(req);
|
||||
} else {
|
||||
super.handleRequest(req);
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc soldier";
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return "Orc soldier";
|
||||
}
|
||||
}
|
||||
|
@ -7,32 +7,32 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public class Request {
|
||||
|
||||
private String requestDescription;
|
||||
private RequestType requestType;
|
||||
private String requestDescription;
|
||||
private RequestType requestType;
|
||||
|
||||
public Request(RequestType requestType, String requestDescription) {
|
||||
this.setRequestType(requestType);
|
||||
this.setRequestDescription(requestDescription);
|
||||
}
|
||||
public Request(RequestType requestType, String requestDescription) {
|
||||
this.setRequestType(requestType);
|
||||
this.setRequestDescription(requestDescription);
|
||||
}
|
||||
|
||||
public String getRequestDescription() {
|
||||
return requestDescription;
|
||||
}
|
||||
public String getRequestDescription() {
|
||||
return requestDescription;
|
||||
}
|
||||
|
||||
public void setRequestDescription(String requestDescription) {
|
||||
this.requestDescription = requestDescription;
|
||||
}
|
||||
public void setRequestDescription(String requestDescription) {
|
||||
this.requestDescription = requestDescription;
|
||||
}
|
||||
|
||||
public RequestType getRequestType() {
|
||||
return requestType;
|
||||
}
|
||||
public RequestType getRequestType() {
|
||||
return requestType;
|
||||
}
|
||||
|
||||
public void setRequestType(RequestType requestType) {
|
||||
this.requestType = requestType;
|
||||
}
|
||||
public void setRequestType(RequestType requestType) {
|
||||
this.requestType = requestType;
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
return getRequestDescription();
|
||||
}
|
||||
@Override
|
||||
public String toString() {
|
||||
return getRequestDescription();
|
||||
}
|
||||
}
|
||||
|
@ -7,22 +7,22 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public abstract class RequestHandler {
|
||||
|
||||
private RequestHandler next;
|
||||
private RequestHandler next;
|
||||
|
||||
public RequestHandler(RequestHandler next) {
|
||||
this.next = next;
|
||||
}
|
||||
public RequestHandler(RequestHandler next) {
|
||||
this.next = next;
|
||||
}
|
||||
|
||||
public void handleRequest(Request req) {
|
||||
if (next != null) {
|
||||
next.handleRequest(req);
|
||||
}
|
||||
}
|
||||
public void handleRequest(Request req) {
|
||||
if (next != null) {
|
||||
next.handleRequest(req);
|
||||
}
|
||||
}
|
||||
|
||||
protected void printHandling(Request req) {
|
||||
System.out.println(this + " handling request \"" + req + "\"");
|
||||
}
|
||||
protected void printHandling(Request req) {
|
||||
System.out.println(this + " handling request \"" + req + "\"");
|
||||
}
|
||||
|
||||
@Override
|
||||
public abstract String toString();
|
||||
@Override
|
||||
public abstract String toString();
|
||||
}
|
||||
|
@ -7,6 +7,6 @@ package com.iluwatar.chain;
|
||||
*/
|
||||
public enum RequestType {
|
||||
|
||||
DEFEND_CASTLE, TORTURE_PRISONER, COLLECT_TAX
|
||||
DEFEND_CASTLE, TORTURE_PRISONER, COLLECT_TAX
|
||||
|
||||
}
|
||||
|
Some files were not shown because too many files have changed in this diff Show More
Reference in New Issue
Block a user