Merge branch 'master' into all-contributors/add-jinishavora
This commit is contained in:
Subhrodip Mohanta
GitHub
commit
07a7b291ce
@ -9,21 +9,156 @@ tags:
|
||||
---
|
||||
|
||||
## Intent
|
||||
|
||||
The Business Delegate pattern adds an abstraction layer between
|
||||
presentation and business tiers. By using the pattern we gain loose coupling
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between the tiers and encapsulate knowledge about how to locate, connect to,
|
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and interact with the business objects that make up the application.
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||||
|
||||
## Explanation
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||||
|
||||
Real world example
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||||
|
||||
> A mobile phone application promises to stream any movie in existence to your phone. It captures
|
||||
> the user's search string and passes this on to the business delegate. The business delegate
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||||
> selects the most suitable video streaming service and plays the video from there.
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|
||||
In Plain Words
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|
||||
> Business delegate adds an abstraction layer between the presentation and business tiers.
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||||
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Wikipedia says
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|
||||
> Business delegate is a Java EE design pattern. This pattern is directing to reduce the coupling
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> in between business services and the connected presentation tier, and to hide the implementation
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> details of services (including lookup and accessibility of EJB architecture). Business delegates
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> acts as an adaptor to invoke business objects from the presentation tier.
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**Programmatic Example**
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First, we have an abstraction for video streaming services and a couple of implementations.
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```java
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public interface VideoStreamingService {
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void doProcessing();
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}
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@Slf4j
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public class NetflixService implements VideoStreamingService {
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@Override
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public void doProcessing() {
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LOGGER.info("NetflixService is now processing");
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}
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}
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@Slf4j
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public class YouTubeService implements VideoStreamingService {
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@Override
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public void doProcessing() {
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LOGGER.info("YouTubeService is now processing");
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}
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}
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```
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Then we have a lookup service that decides which video streaming service is used.
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```java
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@Setter
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public class BusinessLookup {
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private NetflixService netflixService;
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private YouTubeService youTubeService;
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public VideoStreamingService getBusinessService(String movie) {
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if (movie.toLowerCase(Locale.ROOT).contains("die hard")) {
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return netflixService;
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} else {
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return youTubeService;
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}
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}
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}
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```
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The business delegate uses a business lookup to route movie playback requests to a suitable
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video streaming service.
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```java
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@Setter
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public class BusinessDelegate {
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private BusinessLookup lookupService;
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public void playbackMovie(String movie) {
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VideoStreamingService videoStreamingService = lookupService.getBusinessService(movie);
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videoStreamingService.doProcessing();
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}
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}
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```
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The mobile client utilizes business delegate to call the business tier.
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```java
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public class MobileClient {
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private final BusinessDelegate businessDelegate;
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public MobileClient(BusinessDelegate businessDelegate) {
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this.businessDelegate = businessDelegate;
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}
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public void playbackMovie(String movie) {
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businessDelegate.playbackMovie(movie);
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}
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}
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```
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Finally, we can show the full example in action.
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```java
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public static void main(String[] args) {
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// prepare the objects
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var businessDelegate = new BusinessDelegate();
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var businessLookup = new BusinessLookup();
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businessLookup.setNetflixService(new NetflixService());
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businessLookup.setYouTubeService(new YouTubeService());
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businessDelegate.setLookupService(businessLookup);
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// create the client and use the business delegate
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var client = new MobileClient(businessDelegate);
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client.playbackMovie("Die Hard 2");
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client.playbackMovie("Maradona: The Greatest Ever");
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}
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```
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Here is the console output.
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```
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21:15:33.790 [main] INFO com.iluwatar.business.delegate.NetflixService - NetflixService is now processing
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21:15:33.794 [main] INFO com.iluwatar.business.delegate.YouTubeService - YouTubeService is now processing
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```
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## Class diagram
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## Related patterns
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* [Service locator pattern](https://java-design-patterns.com/patterns/service-locator/)
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## Applicability
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Use the Business Delegate pattern when
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* you want loose coupling between presentation and business tiers
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* you want to orchestrate calls to multiple business services
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* you want to encapsulate service lookups and service calls
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* You want loose coupling between presentation and business tiers
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* You want to orchestrate calls to multiple business services
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* You want to encapsulate service lookups and service calls
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## Tutorials
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* [Business Delegate Pattern at TutorialsPoint](https://www.tutorialspoint.com/design_pattern/business_delegate_pattern.htm)
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## Credits
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* [J2EE Design Patterns](https://www.amazon.com/gp/product/0596004273/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596004273&linkCode=as2&tag=javadesignpat-20&linkId=48d37c67fb3d845b802fa9b619ad8f31)
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||||
* [Core J2EE Patterns: Best Practices and Design Strategies](https://www.amazon.com/gp/product/0130648841/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0130648841&linkId=a0100de2b28c71ede8db1757fb2b5947)
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Binary file not shown.
|
Before Width: | Height: | Size: 24 KiB |
@ -1,136 +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="com.iluwatar.business.delegate.BusinessDelegate" project="business-delegate"
|
||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/BusinessDelegate.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="272" y="219"/>
|
||||
<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>
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||||
<class id="2" language="java" name="com.iluwatar.business.delegate.Client" project="business-delegate"
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||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/Client.java" binary="false"
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||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="272" y="64"/>
|
||||
<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="3" language="java" name="com.iluwatar.business.delegate.ServiceType" project="business-delegate"
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||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/ServiceType.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="89" y="383"/>
|
||||
<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>
|
||||
<interface id="4" language="java" name="com.iluwatar.business.delegate.BusinessService" project="business-delegate"
|
||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/BusinessService.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="630" y="365"/>
|
||||
<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>
|
||||
</interface>
|
||||
<class id="5" language="java" name="com.iluwatar.business.delegate.JmsService" project="business-delegate"
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||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/JmsService.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="489" y="210"/>
|
||||
<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="com.iluwatar.business.delegate.BusinessLookup" project="business-delegate"
|
||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/BusinessLookup.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="360" y="399"/>
|
||||
<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="com.iluwatar.business.delegate.EjbService" project="business-delegate"
|
||||
file="/business-delegate/src/main/java/com/iluwatar/business/delegate/EjbService.java" binary="false"
|
||||
corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="668" y="210"/>
|
||||
<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>
|
||||
<realization id="8">
|
||||
<end type="SOURCE" refId="7"/>
|
||||
<end type="TARGET" refId="4"/>
|
||||
</realization>
|
||||
<association id="9">
|
||||
<end type="SOURCE" refId="1" navigable="false">
|
||||
<attribute id="10" name="lookupService">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</attribute>
|
||||
<multiplicity id="11" minimum="0" maximum="1">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</multiplicity>
|
||||
</end>
|
||||
<end type="TARGET" refId="6" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<association id="12">
|
||||
<end type="SOURCE" refId="1" navigable="false">
|
||||
<attribute id="13" name="serviceType">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</attribute>
|
||||
<multiplicity id="14" minimum="0" maximum="1">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</multiplicity>
|
||||
</end>
|
||||
<end type="TARGET" refId="3" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<realization id="15">
|
||||
<end type="SOURCE" refId="5"/>
|
||||
<end type="TARGET" refId="4"/>
|
||||
</realization>
|
||||
<association id="16">
|
||||
<end type="SOURCE" refId="2" navigable="false">
|
||||
<attribute id="17" name="businessDelegate">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</attribute>
|
||||
<multiplicity id="18" minimum="0" maximum="1">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</multiplicity>
|
||||
</end>
|
||||
<end type="TARGET" refId="1" navigable="true"/>
|
||||
<display labels="true" multiplicity="true"/>
|
||||
</association>
|
||||
<association id="19">
|
||||
<end type="SOURCE" refId="1" navigable="false">
|
||||
<attribute id="20" name="businessService">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</attribute>
|
||||
<multiplicity id="21" minimum="0" maximum="1">
|
||||
<position height="0" width="0" x="0" y="0"/>
|
||||
</multiplicity>
|
||||
</end>
|
||||
<end type="TARGET" refId="4" 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>
|
||||
BIN
business-delegate/etc/business-delegate.urm.png
Normal file
BIN
business-delegate/etc/business-delegate.urm.png
Normal file
Binary file not shown.
|
After Width: | Height: | Size: 49 KiB |
@ -5,53 +5,42 @@ package com.iluwatar.business.delegate {
|
||||
+ main(args : String[]) {static}
|
||||
}
|
||||
class BusinessDelegate {
|
||||
- businessService : BusinessService
|
||||
- lookupService : BusinessLookup
|
||||
- serviceType : ServiceType
|
||||
+ BusinessDelegate()
|
||||
+ doTask()
|
||||
+ setLookupService(businessLookup : BusinessLookup)
|
||||
+ setServiceType(serviceType : ServiceType)
|
||||
+ playbackMovie(movie : String)
|
||||
+ setLookupService(lookupService : BusinessLookup)
|
||||
}
|
||||
class BusinessLookup {
|
||||
- ejbService : EjbService
|
||||
- jmsService : JmsService
|
||||
- netflixService : NetflixService
|
||||
- youTubeService : YouTubeService
|
||||
+ BusinessLookup()
|
||||
+ getBusinessService(serviceType : ServiceType) : BusinessService
|
||||
+ setEjbService(ejbService : EjbService)
|
||||
+ setJmsService(jmsService : JmsService)
|
||||
+ getBusinessService(movie : String) : VideoStreamingService
|
||||
+ setNetflixService(netflixService : NetflixService)
|
||||
+ setYouTubeService(youTubeService : YouTubeService)
|
||||
}
|
||||
interface BusinessService {
|
||||
class MobileClient {
|
||||
- businessDelegate : BusinessDelegate
|
||||
+ MobileClient(businessDelegate : BusinessDelegate)
|
||||
+ playbackMovie(movie : String)
|
||||
}
|
||||
class NetflixService {
|
||||
- LOGGER : Logger {static}
|
||||
+ NetflixService()
|
||||
+ doProcessing()
|
||||
}
|
||||
interface VideoStreamingService {
|
||||
+ doProcessing() {abstract}
|
||||
}
|
||||
class Client {
|
||||
- businessDelegate : BusinessDelegate
|
||||
+ Client(businessDelegate : BusinessDelegate)
|
||||
+ doTask()
|
||||
}
|
||||
class EjbService {
|
||||
class YouTubeService {
|
||||
- LOGGER : Logger {static}
|
||||
+ EjbService()
|
||||
+ YouTubeService()
|
||||
+ doProcessing()
|
||||
}
|
||||
class JmsService {
|
||||
- LOGGER : Logger {static}
|
||||
+ JmsService()
|
||||
+ doProcessing()
|
||||
}
|
||||
enum ServiceType {
|
||||
+ EJB {static}
|
||||
+ JMS {static}
|
||||
+ valueOf(name : String) : ServiceType {static}
|
||||
+ values() : ServiceType[] {static}
|
||||
}
|
||||
}
|
||||
BusinessLookup --> "-ejbService" EjbService
|
||||
BusinessDelegate --> "-serviceType" ServiceType
|
||||
Client --> "-businessDelegate" BusinessDelegate
|
||||
BusinessDelegate --> "-businessService" BusinessService
|
||||
BusinessLookup --> "-netflixService" NetflixService
|
||||
BusinessLookup --> "-youTubeService" YouTubeService
|
||||
MobileClient --> "-businessDelegate" BusinessDelegate
|
||||
BusinessDelegate --> "-lookupService" BusinessLookup
|
||||
BusinessLookup --> "-jmsService" JmsService
|
||||
EjbService ..|> BusinessService
|
||||
JmsService ..|> BusinessService
|
||||
NetflixService ..|> VideoStreamingService
|
||||
YouTubeService ..|> VideoStreamingService
|
||||
@enduml
|
||||
@ -33,9 +33,9 @@ package com.iluwatar.business.delegate;
|
||||
* 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.
|
||||
* <p>In this example the client ({@link MobileClient}) utilizes a business delegate (
|
||||
* {@link BusinessDelegate}) to search for movies in video streaming services. The Business Delegate
|
||||
* then selects the appropriate service and makes the service call.
|
||||
*/
|
||||
public class App {
|
||||
|
||||
@ -46,18 +46,16 @@ public class App {
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
// prepare the objects
|
||||
var businessDelegate = new BusinessDelegate();
|
||||
var businessLookup = new BusinessLookup();
|
||||
businessLookup.setEjbService(new EjbService());
|
||||
businessLookup.setJmsService(new JmsService());
|
||||
|
||||
businessLookup.setNetflixService(new NetflixService());
|
||||
businessLookup.setYouTubeService(new YouTubeService());
|
||||
businessDelegate.setLookupService(businessLookup);
|
||||
businessDelegate.setServiceType(ServiceType.EJB);
|
||||
|
||||
var client = new Client(businessDelegate);
|
||||
client.doTask();
|
||||
|
||||
businessDelegate.setServiceType(ServiceType.JMS);
|
||||
client.doTask();
|
||||
// create the client and use the business delegate
|
||||
var client = new MobileClient(businessDelegate);
|
||||
client.playbackMovie("Die Hard 2");
|
||||
client.playbackMovie("Maradona: The Greatest Ever");
|
||||
}
|
||||
}
|
||||
|
||||
@ -23,24 +23,18 @@
|
||||
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
import lombok.Setter;
|
||||
|
||||
/**
|
||||
* BusinessDelegate separates the presentation and business tiers.
|
||||
*/
|
||||
@Setter
|
||||
public class BusinessDelegate {
|
||||
|
||||
private BusinessLookup lookupService;
|
||||
private ServiceType serviceType;
|
||||
|
||||
public void setLookupService(BusinessLookup businessLookup) {
|
||||
this.lookupService = businessLookup;
|
||||
}
|
||||
|
||||
public void setServiceType(ServiceType serviceType) {
|
||||
this.serviceType = serviceType;
|
||||
}
|
||||
|
||||
public void doTask() {
|
||||
BusinessService businessService = lookupService.getBusinessService(serviceType);
|
||||
businessService.doProcessing();
|
||||
public void playbackMovie(String movie) {
|
||||
VideoStreamingService videoStreamingService = lookupService.getBusinessService(movie);
|
||||
videoStreamingService.doProcessing();
|
||||
}
|
||||
}
|
||||
|
||||
@ -23,6 +23,7 @@
|
||||
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
import java.util.Locale;
|
||||
import lombok.Setter;
|
||||
|
||||
/**
|
||||
@ -31,21 +32,21 @@ import lombok.Setter;
|
||||
@Setter
|
||||
public class BusinessLookup {
|
||||
|
||||
private EjbService ejbService;
|
||||
private NetflixService netflixService;
|
||||
|
||||
private JmsService jmsService;
|
||||
private YouTubeService youTubeService;
|
||||
|
||||
/**
|
||||
* Gets service instance based on service type.
|
||||
* Gets service instance based on given movie search string.
|
||||
*
|
||||
* @param serviceType Type of service instance to be returned.
|
||||
* @param movie Search string for the movie.
|
||||
* @return Service instance.
|
||||
*/
|
||||
public BusinessService getBusinessService(ServiceType serviceType) {
|
||||
if (serviceType.equals(ServiceType.EJB)) {
|
||||
return ejbService;
|
||||
public VideoStreamingService getBusinessService(String movie) {
|
||||
if (movie.toLowerCase(Locale.ROOT).contains("die hard")) {
|
||||
return netflixService;
|
||||
} else {
|
||||
return jmsService;
|
||||
return youTubeService;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@ -24,17 +24,17 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
/**
|
||||
* Client utilizes BusinessDelegate to call the business tier.
|
||||
* MobileClient utilizes BusinessDelegate to call the business tier.
|
||||
*/
|
||||
public class Client {
|
||||
public class MobileClient {
|
||||
|
||||
private final BusinessDelegate businessDelegate;
|
||||
|
||||
public Client(BusinessDelegate businessDelegate) {
|
||||
public MobileClient(BusinessDelegate businessDelegate) {
|
||||
this.businessDelegate = businessDelegate;
|
||||
}
|
||||
|
||||
public void doTask() {
|
||||
businessDelegate.doTask();
|
||||
public void playbackMovie(String movie) {
|
||||
businessDelegate.playbackMovie(movie);
|
||||
}
|
||||
}
|
||||
@ -26,13 +26,13 @@ package com.iluwatar.business.delegate;
|
||||
import lombok.extern.slf4j.Slf4j;
|
||||
|
||||
/**
|
||||
* Service EJB implementation.
|
||||
* NetflixService implementation.
|
||||
*/
|
||||
@Slf4j
|
||||
public class EjbService implements BusinessService {
|
||||
public class NetflixService implements VideoStreamingService {
|
||||
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
LOGGER.info("EjbService is now processing");
|
||||
LOGGER.info("NetflixService is now processing");
|
||||
}
|
||||
}
|
||||
@ -1,33 +0,0 @@
|
||||
/*
|
||||
* The MIT License
|
||||
* Copyright © 2014-2021 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.business.delegate;
|
||||
|
||||
/**
|
||||
* Enumeration for service types.
|
||||
*/
|
||||
public enum ServiceType {
|
||||
|
||||
EJB,
|
||||
JMS
|
||||
}
|
||||
@ -24,9 +24,9 @@
|
||||
package com.iluwatar.business.delegate;
|
||||
|
||||
/**
|
||||
* Interface for service implementations.
|
||||
* Interface for video streaming service implementations.
|
||||
*/
|
||||
public interface BusinessService {
|
||||
public interface VideoStreamingService {
|
||||
|
||||
void doProcessing();
|
||||
}
|
||||
@ -26,13 +26,13 @@ package com.iluwatar.business.delegate;
|
||||
import lombok.extern.slf4j.Slf4j;
|
||||
|
||||
/**
|
||||
* Service JMS implementation.
|
||||
* YouTubeService implementation.
|
||||
*/
|
||||
@Slf4j
|
||||
public class JmsService implements BusinessService {
|
||||
public class YouTubeService implements VideoStreamingService {
|
||||
|
||||
@Override
|
||||
public void doProcessing() {
|
||||
LOGGER.info("JmsService is now processing");
|
||||
LOGGER.info("YouTubeService is now processing");
|
||||
}
|
||||
}
|
||||
@ -26,25 +26,20 @@ package com.iluwatar.business.delegate;
|
||||
import org.junit.jupiter.api.BeforeEach;
|
||||
import org.junit.jupiter.api.Test;
|
||||
|
||||
|
||||
import static org.mockito.ArgumentMatchers.anyString;
|
||||
import static org.mockito.Mockito.spy;
|
||||
import static org.mockito.Mockito.times;
|
||||
import static org.mockito.Mockito.verify;
|
||||
|
||||
/**
|
||||
* 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.
|
||||
* Tests for the {@link BusinessDelegate}
|
||||
*/
|
||||
class BusinessDelegateTest {
|
||||
|
||||
private EjbService ejbService;
|
||||
private NetflixService netflixService;
|
||||
|
||||
private JmsService jmsService;
|
||||
private YouTubeService youTubeService;
|
||||
|
||||
private BusinessDelegate businessDelegate;
|
||||
|
||||
@ -54,19 +49,19 @@ class BusinessDelegateTest {
|
||||
*/
|
||||
@BeforeEach
|
||||
public void setup() {
|
||||
ejbService = spy(new EjbService());
|
||||
jmsService = spy(new JmsService());
|
||||
netflixService = spy(new NetflixService());
|
||||
youTubeService = spy(new YouTubeService());
|
||||
|
||||
BusinessLookup businessLookup = spy(new BusinessLookup());
|
||||
businessLookup.setEjbService(ejbService);
|
||||
businessLookup.setJmsService(jmsService);
|
||||
businessLookup.setNetflixService(netflixService);
|
||||
businessLookup.setYouTubeService(youTubeService);
|
||||
|
||||
businessDelegate = spy(new BusinessDelegate());
|
||||
businessDelegate.setLookupService(businessLookup);
|
||||
}
|
||||
|
||||
/**
|
||||
* In this example the client ({@link Client}) utilizes a business delegate (
|
||||
* In this example the client ({@link MobileClient}) utilizes a business delegate (
|
||||
* {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
|
||||
* service and makes the service call.
|
||||
*/
|
||||
@ -74,26 +69,20 @@ class BusinessDelegateTest {
|
||||
void testBusinessDelegate() {
|
||||
|
||||
// setup a client object
|
||||
var client = new Client(businessDelegate);
|
||||
|
||||
// set the service type
|
||||
businessDelegate.setServiceType(ServiceType.EJB);
|
||||
var client = new MobileClient(businessDelegate);
|
||||
|
||||
// action
|
||||
client.doTask();
|
||||
client.playbackMovie("Die hard");
|
||||
|
||||
// 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);
|
||||
// verifying that the businessDelegate was used by client during playbackMovie() method.
|
||||
verify(businessDelegate).playbackMovie(anyString());
|
||||
verify(netflixService).doProcessing();
|
||||
|
||||
// action
|
||||
client.doTask();
|
||||
client.playbackMovie("Maradona");
|
||||
|
||||
// verifying that the businessDelegate was used by client during doTask() method.
|
||||
verify(businessDelegate, times(2)).doTask();
|
||||
verify(jmsService).doProcessing();
|
||||
verify(businessDelegate, times(2)).playbackMovie(anyString());
|
||||
verify(youTubeService).doProcessing();
|
||||
}
|
||||
}
|
||||
|
||||
@ -9,18 +9,234 @@ tags:
|
||||
---
|
||||
|
||||
## Intent
|
||||
Allows to encode behaviour as instructions for virtual machine.
|
||||
|
||||
Allows encoding behavior as instructions for a virtual machine.
|
||||
|
||||
## Explanation
|
||||
|
||||
Real world example
|
||||
|
||||
> A team is working on a new game where wizards battle against each other. The wizard behavior
|
||||
> needs to be carefully adjusted and iterated hundreds of times through playtesting. It's not
|
||||
> optimal to ask the programmer to make changes each time the game designer wants to vary the
|
||||
> behavior, so the wizard behavior is implemented as a data-driven virtual machine.
|
||||
|
||||
In plain words
|
||||
|
||||
> Bytecode pattern enables behavior driven by data instead of code.
|
||||
|
||||
[Gameprogrammingpatterns.com](https://gameprogrammingpatterns.com/bytecode.html) documentation
|
||||
states:
|
||||
|
||||
> An instruction set defines the low-level operations that can be performed. A series of
|
||||
> instructions is encoded as a sequence of bytes. A virtual machine executes these instructions one
|
||||
> at a time, using a stack for intermediate values. By combining instructions, complex high-level
|
||||
> behavior can be defined.
|
||||
|
||||
**Programmatic Example**
|
||||
|
||||
One of the most important game objects is the `Wizard` class.
|
||||
|
||||
```java
|
||||
@AllArgsConstructor
|
||||
@Setter
|
||||
@Getter
|
||||
@Slf4j
|
||||
public class Wizard {
|
||||
|
||||
private int health;
|
||||
private int agility;
|
||||
private int wisdom;
|
||||
private int numberOfPlayedSounds;
|
||||
private int numberOfSpawnedParticles;
|
||||
|
||||
public void playSound() {
|
||||
LOGGER.info("Playing sound");
|
||||
numberOfPlayedSounds++;
|
||||
}
|
||||
|
||||
public void spawnParticles() {
|
||||
LOGGER.info("Spawning particles");
|
||||
numberOfSpawnedParticles++;
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
Next, we show the available instructions for our virtual machine. Each of the instructions has its
|
||||
own semantics on how it operates with the stack data. For example, the ADD instruction takes the top
|
||||
two items from the stack, adds them together and pushes the result to the stack.
|
||||
|
||||
```java
|
||||
@AllArgsConstructor
|
||||
@Getter
|
||||
public enum Instruction {
|
||||
|
||||
LITERAL(1), // e.g. "LITERAL 0", push 0 to stack
|
||||
SET_HEALTH(2), // e.g. "SET_HEALTH", pop health and wizard number, call set health
|
||||
SET_WISDOM(3), // e.g. "SET_WISDOM", pop wisdom and wizard number, call set wisdom
|
||||
SET_AGILITY(4), // e.g. "SET_AGILITY", pop agility and wizard number, call set agility
|
||||
PLAY_SOUND(5), // e.g. "PLAY_SOUND", pop value as wizard number, call play sound
|
||||
SPAWN_PARTICLES(6), // e.g. "SPAWN_PARTICLES", pop value as wizard number, call spawn particles
|
||||
GET_HEALTH(7), // e.g. "GET_HEALTH", pop value as wizard number, push wizard's health
|
||||
GET_AGILITY(8), // e.g. "GET_AGILITY", pop value as wizard number, push wizard's agility
|
||||
GET_WISDOM(9), // e.g. "GET_WISDOM", pop value as wizard number, push wizard's wisdom
|
||||
ADD(10), // e.g. "ADD", pop 2 values, push their sum
|
||||
DIVIDE(11); // e.g. "DIVIDE", pop 2 values, push their division
|
||||
// ...
|
||||
}
|
||||
```
|
||||
|
||||
At the heart of our example is the `VirtualMachine` class. It takes instructions as input and
|
||||
executes them to provide the game object behavior.
|
||||
|
||||
```java
|
||||
@Getter
|
||||
@Slf4j
|
||||
public class VirtualMachine {
|
||||
|
||||
private final Stack<Integer> stack = new Stack<>();
|
||||
|
||||
private final Wizard[] wizards = new Wizard[2];
|
||||
|
||||
public VirtualMachine() {
|
||||
wizards[0] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
|
||||
0, 0);
|
||||
wizards[1] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
|
||||
0, 0);
|
||||
}
|
||||
|
||||
public VirtualMachine(Wizard wizard1, Wizard wizard2) {
|
||||
wizards[0] = wizard1;
|
||||
wizards[1] = wizard2;
|
||||
}
|
||||
|
||||
public void execute(int[] bytecode) {
|
||||
for (var i = 0; i < bytecode.length; i++) {
|
||||
Instruction instruction = Instruction.getInstruction(bytecode[i]);
|
||||
switch (instruction) {
|
||||
case LITERAL:
|
||||
// Read the next byte from the bytecode.
|
||||
int value = bytecode[++i];
|
||||
// Push the next value to stack
|
||||
stack.push(value);
|
||||
break;
|
||||
case SET_AGILITY:
|
||||
var amount = stack.pop();
|
||||
var wizard = stack.pop();
|
||||
setAgility(wizard, amount);
|
||||
break;
|
||||
case SET_WISDOM:
|
||||
amount = stack.pop();
|
||||
wizard = stack.pop();
|
||||
setWisdom(wizard, amount);
|
||||
break;
|
||||
case SET_HEALTH:
|
||||
amount = stack.pop();
|
||||
wizard = stack.pop();
|
||||
setHealth(wizard, amount);
|
||||
break;
|
||||
case GET_HEALTH:
|
||||
wizard = stack.pop();
|
||||
stack.push(getHealth(wizard));
|
||||
break;
|
||||
case GET_AGILITY:
|
||||
wizard = stack.pop();
|
||||
stack.push(getAgility(wizard));
|
||||
break;
|
||||
case GET_WISDOM:
|
||||
wizard = stack.pop();
|
||||
stack.push(getWisdom(wizard));
|
||||
break;
|
||||
case ADD:
|
||||
var a = stack.pop();
|
||||
var b = stack.pop();
|
||||
stack.push(a + b);
|
||||
break;
|
||||
case DIVIDE:
|
||||
a = stack.pop();
|
||||
b = stack.pop();
|
||||
stack.push(b / a);
|
||||
break;
|
||||
case PLAY_SOUND:
|
||||
wizard = stack.pop();
|
||||
getWizards()[wizard].playSound();
|
||||
break;
|
||||
case SPAWN_PARTICLES:
|
||||
wizard = stack.pop();
|
||||
getWizards()[wizard].spawnParticles();
|
||||
break;
|
||||
default:
|
||||
throw new IllegalArgumentException("Invalid instruction value");
|
||||
}
|
||||
LOGGER.info("Executed " + instruction.name() + ", Stack contains " + getStack());
|
||||
}
|
||||
}
|
||||
|
||||
public void setHealth(int wizard, int amount) {
|
||||
wizards[wizard].setHealth(amount);
|
||||
}
|
||||
// other setters ->
|
||||
// ...
|
||||
}
|
||||
```
|
||||
|
||||
Now we can show the full example utilizing the virtual machine.
|
||||
|
||||
```java
|
||||
public static void main(String[] args) {
|
||||
|
||||
var vm = new VirtualMachine(
|
||||
new Wizard(45, 7, 11, 0, 0),
|
||||
new Wizard(36, 18, 8, 0, 0));
|
||||
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_HEALTH"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_AGILITY"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_WISDOM"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 2"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("DIVIDE"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("SET_HEALTH"));
|
||||
}
|
||||
```
|
||||
|
||||
Here is the console output.
|
||||
|
||||
```
|
||||
16:20:10.193 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0]
|
||||
16:20:10.196 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 0]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_HEALTH, Stack contains [0, 45]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 0]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_AGILITY, Stack contains [0, 45, 7]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 7, 0]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed GET_WISDOM, Stack contains [0, 45, 7, 11]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed ADD, Stack contains [0, 45, 18]
|
||||
16:20:10.197 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed LITERAL, Stack contains [0, 45, 18, 2]
|
||||
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed DIVIDE, Stack contains [0, 45, 9]
|
||||
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed ADD, Stack contains [0, 54]
|
||||
16:20:10.198 [main] INFO com.iluwatar.bytecode.VirtualMachine - Executed SET_HEALTH, Stack contains []
|
||||
```
|
||||
|
||||
## Class diagram
|
||||
|
||||
|
||||
|
||||
## Applicability
|
||||
|
||||
Use the Bytecode pattern when you have a lot of behavior you need to define and your
|
||||
game’s implementation language isn’t a good fit because:
|
||||
|
||||
* it’s too low-level, making it tedious or error-prone to program in.
|
||||
* iterating on it takes too long due to slow compile times or other tooling issues.
|
||||
* it has too much trust. If you want to ensure the behavior being defined can’t break the game, you need to sandbox it from the rest of the codebase.
|
||||
* It’s too low-level, making it tedious or error-prone to program in.
|
||||
* Iterating on it takes too long due to slow compile times or other tooling issues.
|
||||
* It has too much trust. If you want to ensure the behavior being defined can’t break the game, you need to sandbox it from the rest of the codebase.
|
||||
|
||||
## Related patterns
|
||||
|
||||
* [Interpreter](https://java-design-patterns.com/patterns/interpreter/)
|
||||
|
||||
## Credits
|
||||
|
||||
|
||||
Binary file not shown.
|
Before Width: | Height: | Size: 19 KiB |
@ -1,49 +0,0 @@
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<class-diagram version="1.2.3" icons="true" always-add-relationships="false" generalizations="true" realizations="true"
|
||||
associations="true" dependencies="false" nesting-relationships="true" router="FAN">
|
||||
<class id="1" language="java" name="com.iluwatar.bytecode.VirtualMachine" project="bytecode"
|
||||
file="/bytecode/src/main/java/com/iluwatar/bytecode/VirtualMachine.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="455" y="173"/>
|
||||
<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="com.iluwatar.bytecode.App" project="bytecode"
|
||||
file="/bytecode/src/main/java/com/iluwatar/bytecode/App.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="148" y="110"/>
|
||||
<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="com.iluwatar.bytecode.Wizard" project="bytecode"
|
||||
file="/bytecode/src/main/java/com/iluwatar/bytecode/Wizard.java" binary="false" corner="BOTTOM_RIGHT">
|
||||
<position height="-1" width="-1" x="148" y="416"/>
|
||||
<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="4">
|
||||
<end type="SOURCE" refId="1" navigable="false" variant="ASSOCIATION">
|
||||
<attribute id="5" name="wizards">
|
||||
<position height="18" width="48" x="296" y="291"/>
|
||||
</attribute>
|
||||
<multiplicity id="6" minimum="0" maximum="2147483647">
|
||||
<position height="0" width="0" x="-327" y="-27"/>
|
||||
</multiplicity>
|
||||
</end>
|
||||
<end type="TARGET" refId="3" navigable="true" variant="ASSOCIATION"/>
|
||||
<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>
|
||||
Binary file not shown.
|
Before Width: | Height: | Size: 67 KiB After Width: | Height: | Size: 84 KiB |
@ -3,7 +3,6 @@ package com.iluwatar.bytecode {
|
||||
class App {
|
||||
- LOGGER : Logger {static}
|
||||
+ App()
|
||||
- interpretInstruction(instruction : String, vm : VirtualMachine) {static}
|
||||
+ main(args : String[]) {static}
|
||||
}
|
||||
enum Instruction {
|
||||
@ -18,22 +17,25 @@ package com.iluwatar.bytecode {
|
||||
+ SET_HEALTH {static}
|
||||
+ SET_WISDOM {static}
|
||||
+ SPAWN_PARTICLES {static}
|
||||
- value : int
|
||||
- intValue : int
|
||||
+ getInstruction(value : int) : Instruction {static}
|
||||
+ getIntValue() : int
|
||||
+ valueOf(name : String) : Instruction {static}
|
||||
+ values() : Instruction[] {static}
|
||||
}
|
||||
class VirtualMachine {
|
||||
- LOGGER : Logger {static}
|
||||
- stack : Stack<Integer>
|
||||
- wizards : Wizard[]
|
||||
+ VirtualMachine()
|
||||
+ VirtualMachine(wizard1 : Wizard, wizard2 : Wizard)
|
||||
+ execute(bytecode : int[])
|
||||
+ getAgility(wizard : int) : int
|
||||
+ getHealth(wizard : int) : int
|
||||
+ getStack() : Stack<Integer>
|
||||
+ getWisdom(wizard : int) : int
|
||||
+ getWizards() : Wizard[]
|
||||
- randomInt(min : int, max : int) : int
|
||||
+ setAgility(wizard : int, amount : int)
|
||||
+ setHealth(wizard : int, amount : int)
|
||||
+ setWisdom(wizard : int, amount : int)
|
||||
@ -45,7 +47,7 @@ package com.iluwatar.bytecode {
|
||||
- numberOfPlayedSounds : int
|
||||
- numberOfSpawnedParticles : int
|
||||
- wisdom : int
|
||||
+ Wizard()
|
||||
+ Wizard(health : int, agility : int, wisdom : int, numberOfPlayedSounds : int, numberOfSpawnedParticles : int)
|
||||
+ getAgility() : int
|
||||
+ getHealth() : int
|
||||
+ getNumberOfPlayedSounds() : int
|
||||
@ -54,6 +56,8 @@ package com.iluwatar.bytecode {
|
||||
+ playSound()
|
||||
+ setAgility(agility : int)
|
||||
+ setHealth(health : int)
|
||||
+ setNumberOfPlayedSounds(numberOfPlayedSounds : int)
|
||||
+ setNumberOfSpawnedParticles(numberOfSpawnedParticles : int)
|
||||
+ setWisdom(wisdom : int)
|
||||
+ spawnParticles()
|
||||
}
|
||||
|
||||
@ -49,33 +49,21 @@ public class App {
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
||||
var wizard = new Wizard();
|
||||
wizard.setHealth(45);
|
||||
wizard.setAgility(7);
|
||||
wizard.setWisdom(11);
|
||||
var vm = new VirtualMachine(
|
||||
new Wizard(45, 7, 11, 0, 0),
|
||||
new Wizard(36, 18, 8, 0, 0));
|
||||
|
||||
var vm = new VirtualMachine();
|
||||
vm.getWizards()[0] = wizard;
|
||||
|
||||
String literal = "LITERAL 0";
|
||||
|
||||
interpretInstruction(literal, vm);
|
||||
interpretInstruction(literal, vm);
|
||||
interpretInstruction("GET_HEALTH", vm);
|
||||
interpretInstruction(literal, vm);
|
||||
interpretInstruction("GET_AGILITY", vm);
|
||||
interpretInstruction(literal, vm);
|
||||
interpretInstruction("GET_WISDOM ", vm);
|
||||
interpretInstruction("ADD", vm);
|
||||
interpretInstruction("LITERAL 2", vm);
|
||||
interpretInstruction("DIVIDE", vm);
|
||||
interpretInstruction("ADD", vm);
|
||||
interpretInstruction("SET_HEALTH", vm);
|
||||
}
|
||||
|
||||
private static void interpretInstruction(String instruction, VirtualMachine vm) {
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode(instruction));
|
||||
var stack = vm.getStack();
|
||||
LOGGER.info(instruction + String.format("%" + (12 - instruction.length()) + "s", "") + stack);
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_HEALTH"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_AGILITY"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 0"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("GET_WISDOM"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("LITERAL 2"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("DIVIDE"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("ADD"));
|
||||
vm.execute(InstructionConverterUtil.convertToByteCode("SET_HEALTH"));
|
||||
}
|
||||
}
|
||||
|
||||
@ -33,17 +33,17 @@ import lombok.Getter;
|
||||
@Getter
|
||||
public enum Instruction {
|
||||
|
||||
LITERAL(1),
|
||||
SET_HEALTH(2),
|
||||
SET_WISDOM(3),
|
||||
SET_AGILITY(4),
|
||||
PLAY_SOUND(5),
|
||||
SPAWN_PARTICLES(6),
|
||||
GET_HEALTH(7),
|
||||
GET_AGILITY(8),
|
||||
GET_WISDOM(9),
|
||||
ADD(10),
|
||||
DIVIDE(11);
|
||||
LITERAL(1), // e.g. "LITERAL 0", push 0 to stack
|
||||
SET_HEALTH(2), // e.g. "SET_HEALTH", pop health and wizard number, call set health
|
||||
SET_WISDOM(3), // e.g. "SET_WISDOM", pop wisdom and wizard number, call set wisdom
|
||||
SET_AGILITY(4), // e.g. "SET_AGILITY", pop agility and wizard number, call set agility
|
||||
PLAY_SOUND(5), // e.g. "PLAY_SOUND", pop value as wizard number, call play sound
|
||||
SPAWN_PARTICLES(6), // e.g. "SPAWN_PARTICLES", pop value as wizard number, call spawn particles
|
||||
GET_HEALTH(7), // e.g. "GET_HEALTH", pop value as wizard number, push wizard's health
|
||||
GET_AGILITY(8), // e.g. "GET_AGILITY", pop value as wizard number, push wizard's agility
|
||||
GET_WISDOM(9), // e.g. "GET_WISDOM", pop value as wizard number, push wizard's wisdom
|
||||
ADD(10), // e.g. "ADD", pop 2 values, push their sum
|
||||
DIVIDE(11); // e.g. "DIVIDE", pop 2 values, push their division
|
||||
|
||||
private final int intValue;
|
||||
|
||||
|
||||
@ -24,12 +24,15 @@
|
||||
package com.iluwatar.bytecode;
|
||||
|
||||
import java.util.Stack;
|
||||
import java.util.concurrent.ThreadLocalRandom;
|
||||
import lombok.Getter;
|
||||
import lombok.extern.slf4j.Slf4j;
|
||||
|
||||
/**
|
||||
* Implementation of virtual machine.
|
||||
*/
|
||||
@Getter
|
||||
@Slf4j
|
||||
public class VirtualMachine {
|
||||
|
||||
private final Stack<Integer> stack = new Stack<>();
|
||||
@ -37,12 +40,21 @@ public class VirtualMachine {
|
||||
private final Wizard[] wizards = new Wizard[2];
|
||||
|
||||
/**
|
||||
* Constructor.
|
||||
* No-args constructor.
|
||||
*/
|
||||
public VirtualMachine() {
|
||||
for (var i = 0; i < wizards.length; i++) {
|
||||
wizards[i] = new Wizard();
|
||||
}
|
||||
wizards[0] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
|
||||
0, 0);
|
||||
wizards[1] = new Wizard(randomInt(3, 32), randomInt(3, 32), randomInt(3, 32),
|
||||
0, 0);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructor taking the wizards as arguments.
|
||||
*/
|
||||
public VirtualMachine(Wizard wizard1, Wizard wizard2) {
|
||||
wizards[0] = wizard1;
|
||||
wizards[1] = wizard2;
|
||||
}
|
||||
|
||||
/**
|
||||
@ -57,6 +69,7 @@ public class VirtualMachine {
|
||||
case LITERAL:
|
||||
// Read the next byte from the bytecode.
|
||||
int value = bytecode[++i];
|
||||
// Push the next value to stack
|
||||
stack.push(value);
|
||||
break;
|
||||
case SET_AGILITY:
|
||||
@ -107,6 +120,7 @@ public class VirtualMachine {
|
||||
default:
|
||||
throw new IllegalArgumentException("Invalid instruction value");
|
||||
}
|
||||
LOGGER.info("Executed " + instruction.name() + ", Stack contains " + getStack());
|
||||
}
|
||||
}
|
||||
|
||||
@ -133,4 +147,8 @@ public class VirtualMachine {
|
||||
public int getAgility(int wizard) {
|
||||
return wizards[wizard].getAgility();
|
||||
}
|
||||
|
||||
private int randomInt(int min, int max) {
|
||||
return ThreadLocalRandom.current().nextInt(min, max + 1);
|
||||
}
|
||||
}
|
||||
|
||||
@ -23,6 +23,7 @@
|
||||
|
||||
package com.iluwatar.bytecode;
|
||||
|
||||
import lombok.AllArgsConstructor;
|
||||
import lombok.Getter;
|
||||
import lombok.Setter;
|
||||
import lombok.extern.slf4j.Slf4j;
|
||||
@ -31,16 +32,15 @@ import lombok.extern.slf4j.Slf4j;
|
||||
* This class represent game objects which properties can be changed by instructions interpreted by
|
||||
* virtual machine.
|
||||
*/
|
||||
@AllArgsConstructor
|
||||
@Setter
|
||||
@Getter
|
||||
@Slf4j
|
||||
public class Wizard {
|
||||
|
||||
private int health;
|
||||
|
||||
private int agility;
|
||||
private int wisdom;
|
||||
|
||||
private int numberOfPlayedSounds;
|
||||
private int numberOfSpawnedParticles;
|
||||
|
||||
@ -53,5 +53,4 @@ public class Wizard {
|
||||
LOGGER.info("Spawning particles");
|
||||
numberOfSpawnedParticles++;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
@ -73,6 +73,4 @@ public class InstructionConverterUtil {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
}
|
||||
|
||||
@ -99,11 +99,11 @@ public class BookViewModel {
|
||||
</zk>
|
||||
```
|
||||
|
||||
Note:
|
||||
* To deploy this, go to model-view-viewmodel folder and run:
|
||||
* mvn clean install
|
||||
* mvn jetty:run -Djetty.http.port=9911
|
||||
* In browser, http://localhost:9911/model-view-viewmodel/
|
||||
To deploy the example, go to model-view-viewmodel folder and run:
|
||||
|
||||
* `mvn clean install`
|
||||
* `mvn jetty:run -Djetty.http.port=9911`
|
||||
* Open browser to address: http://localhost:9911/model-view-viewmodel/
|
||||
|
||||
## Class diagram
|
||||
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user