gaspersic/java-design-patterns
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Work on #404, javadocs and test cases for DB and in memory dao.

Browse Source
This commit is contained in:
Narendra Pathai
2016-03-21 17:55:29 +05:30
parent 448d855809
commit fa077c8be9
8 changed files with 345 additions and 213 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
dao/src/main/java/com/iluwatar/dao/App.java
View File

@@ -49,9 +49,11 @@ public class App {
* Program entry point.
*
* @param args command line args.
* @throws Exception if any error occurs.
*/
public static void main(final String[] args) {
final CustomerDao customerDao = new InMemoryCustomerDao(generateSampleCustomers());
public static void main(final String[] args) throws Exception {
final CustomerDao customerDao = new InMemoryCustomerDao();
addCustomers(customerDao);
log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
log.info("customerDao.getCusterById(2): " + customerDao.getById(2));
final Customer customer = new Customer(4, "Dan", "Danson");
@@ -65,6 +67,12 @@ public class App {
log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
}
private static void addCustomers(CustomerDao customerDao) throws Exception {
for (Customer customer : generateSampleCustomers()) {
customerDao.add(customer);
}
}
/**
* Generate customers.
*

52
dao/src/main/java/com/iluwatar/dao/CustomerDao.java
View File

@@ -26,18 +26,54 @@ import java.util.stream.Stream;
/**
*
* CustomerDao
*
* In an application the Data Access Object (DAO) is a part of Data access layer. It is an object
* that provides an interface to some type of persistence mechanism. By mapping application calls
* to the persistence layer, DAO provides some specific data operations without exposing details
* of the database. This isolation supports the Single responsibility principle. It separates what
* data accesses the application needs, in terms of domain-specific objects and data types
* (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS,
* database schema, etc.
* <br/><br/>
* Any change in the way data is stored and retrieved will not change the client code as the client
* will be using interface and need not worry about exact source.
*
* @see InMemoryCustomerDao
* @see DBCustomerDao
*/
public interface CustomerDao {
Stream<Customer> getAll();
/**
* @return all the customers as a stream. The stream may be lazily or eagerly evaluated based on the
* implementation. The stream must be closed after use.
* @throws Exception if any error occurs.
*/
Stream<Customer> getAll() throws Exception;
/**
* @param id unique identifier of the customer.
* @return customer with unique identifier <code>id</code> is found, null otherwise.
* @throws Exception if any error occurs.
*/
Customer getById(int id) throws Exception;
Customer getById(int id);
/**
* @param customer the customer to be added.
* @return true if customer is successfully added, false if customer already exists.
* @throws Exception if any error occurs.
*/
boolean add(Customer customer) throws Exception;
boolean add(Customer customer);
/**
* @param customer the customer to be updated.
* @return true if customer exists and is successfully updated, false otherwise.
* @throws Exception if any error occurs.
*/
boolean update(Customer customer) throws Exception;
boolean update(Customer customer);
boolean delete(Customer customer);
/**
* @param customer the customer to be deleted.
* @return true if customer exists and is successfully deleted, false otherwise.
* @throws Exception if any error occurs.
*/
boolean delete(Customer customer) throws Exception;
}

72
dao/src/main/java/com/iluwatar/dao/DBCustomerDao.java
View File

@@ -1,7 +1,28 @@
/**
* The MIT License
* Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
@@ -11,16 +32,22 @@ import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import javax.sql.DataSource;
/**
*
*
*/
public class DBCustomerDao implements CustomerDao {
private String dbUrl;
private final DataSource dataSource;
public DBCustomerDao(String dbUrl) {
this.dbUrl = dbUrl;
public DBCustomerDao(DataSource dataSource) {
this.dataSource = dataSource;
}
@Override
public Stream<Customer> getAll() {
public Stream<Customer> getAll() throws Exception {
Connection connection;
try {
@@ -41,14 +68,16 @@ public class DBCustomerDao implements CustomerDao {
e.printStackTrace();
return false;
}
}}, false).onClose(() -> mutedClose(connection));
} catch (SQLException e) {
e.printStackTrace();
return null;
throw new Exception(e.getMessage(), e);
}
}
private Connection getConnection() throws SQLException {
return dataSource.getConnection();
}
private void mutedClose(Connection connection) {
try {
connection.close();
@@ -64,22 +93,23 @@ public class DBCustomerDao implements CustomerDao {
}
@Override
public Customer getById(int id) {
public Customer getById(int id) throws Exception {
try (Connection connection = getConnection();
PreparedStatement statement = connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
statement.setInt(1, id);
ResultSet resultSet = statement.executeQuery();
if (resultSet.next()) {
return createCustomer(resultSet);
} else {
return null;
}
} catch (SQLException ex) {
ex.printStackTrace();
throw new Exception(ex.getMessage(), ex);
}
return null;
}
@Override
public boolean add(Customer customer) {
public boolean add(Customer customer) throws Exception {
if (getById(customer.getId()) != null) {
return false;
}
@@ -92,13 +122,12 @@ public class DBCustomerDao implements CustomerDao {
statement.execute();
return true;
} catch (SQLException ex) {
ex.printStackTrace();
return false;
throw new Exception(ex.getMessage(), ex);
}
}
@Override
public boolean update(Customer customer) {
public boolean update(Customer customer) throws Exception {
try (Connection connection = getConnection();
PreparedStatement statement = connection.prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
statement.setString(1, customer.getFirstName());
@@ -106,25 +135,18 @@ public class DBCustomerDao implements CustomerDao {
statement.setInt(3, customer.getId());
return statement.executeUpdate() > 0;
} catch (SQLException ex) {
ex.printStackTrace();
return false;
throw new Exception(ex.getMessage(), ex);
}
}
@Override
public boolean delete(Customer customer) {
public boolean delete(Customer customer) throws Exception {
try (Connection connection = getConnection();
PreparedStatement statement = connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
statement.setInt(1, customer.getId());
return statement.executeUpdate() > 0;
} catch (SQLException ex) {
ex.printStackTrace();
return false;
throw new Exception(ex.getMessage(), ex);
}
}
private Connection getConnection() throws SQLException {
return DriverManager.getConnection(dbUrl);
}
}

23
dao/src/main/java/com/iluwatar/dao/InMemoryCustomerDao.java
View File

@@ -23,30 +23,22 @@
package com.iluwatar.dao;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Stream;
/**
*
* The data access object (DAO) is an object that provides an abstract interface to some type of
* database or other persistence mechanism. By mapping application calls to the persistence layer,
* DAO provide some specific data operations without exposing details of the database. This
* isolation supports the Single responsibility principle. It separates what data accesses the
* application needs, in terms of domain-specific objects and data types (the public interface of
* the DAO), from how these needs can be satisfied with a specific DBMS, database schema, etc.
*
* An in memory implementation of {@link CustomerDao}, which stores the customers in JVM memory
* and data is lost when the application exits.
* <br/>
* This implementation is useful as temporary database or for testing.
*/
// TODO update the javadoc
public class InMemoryCustomerDao implements CustomerDao {
private Map<Integer, Customer> idToCustomer = new HashMap<>();
public InMemoryCustomerDao(final List<Customer> customers) {
customers.stream()
.forEach((customer) -> idToCustomer.put(customer.getId(), customer));
}
/**
* An eagerly evaluated stream of customers stored in memory.
*/
@Override
public Stream<Customer> getAll() {
return idToCustomer.values().stream();
@@ -67,7 +59,6 @@ public class InMemoryCustomerDao implements CustomerDao {
return true;
}
@Override
public boolean update(final Customer customer) {
return idToCustomer.replace(customer.getId(), customer) != null;