组合实体模式

组合实体模式(Composite Entity Pattern)用在 EJB 持久化机制中。一个组合实体是一个 EJB 实体 bean,代表了对象的图解。

当更新一个组合实体时,内部依赖对象 beans 会自动更新,因为它们是由 EJB 实体 bean 管理的。以下是组合实体 bean 的参与者。

  • 组合实体(Composite Entity)

它是主要的实体 bean。它可以是粗粒的,或者可以包含一个粗粒度对象,用于持续生命周期。

  • 粗粒度对象(Coarse-Grained Object)

该对象包含依赖对象。它有自己的生命周期,也能管理依赖对象的生命周期。

  • 依赖对象(Dependent Object)

依赖对象是一个持续生命周期依赖于粗粒度对象的对象。

  • 策略(Strategies)

策略表示如何实现组合实体。

实际案例

类信息概览:

类名 说明
Main.java 方法的总入口
Client.java 客户端
DependentObjectOne.java 依赖实体 one
DependentObjectTwo.java 依赖实体 two
CompositeEntity.java 组合实体
CoarseGrainedObject.java 粗粒度的实体

定义

  • Client.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> 创建使用组合实体的客户端类 </p>
 *
 * <pre> Created: 2018/5/27 下午7:19  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class Client {

    private CompositeEntity compositeEntity = new CompositeEntity();

    public void printData(){
        for (int i = 0; i < compositeEntity.getData().length; i++) {
            System.out.println("Data: " + compositeEntity.getData()[i]);
        }
    }

    public void setData(String data1, String data2){
        compositeEntity.setData(data1, data2);
    }

}

  • DependentObjectTwo.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> 依赖对象 </p>
 *
 * <pre> Created: 2018/5/27 下午7:15  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class DependentObjectTwo {

    private String data;

    public void setData(String data){
        this.data = data;
    }

    public String getData(){
        return data;
    }

}

  • CompositeEntity.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> 创建组合实体 </p>
 *
 * <pre> Created: 2018/5/27 下午7:18  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class CompositeEntity {

    private CoarseGrainedObject cgo = new CoarseGrainedObject();

    public void setData(String data1, String data2){
        cgo.setData(data1, data2);
    }

    public String[] getData(){
        return cgo.getData();
    }

}

  • CoarseGrainedObject.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> 创建粗粒度对象 </p>
 *
 * <pre> Created: 2018/5/27 下午7:16  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class CoarseGrainedObject {

    DependentObjectOne do1 = new DependentObjectOne();
    DependentObjectTwo do2 = new DependentObjectTwo();

    public void setData(String data1, String data2){
        do1.setData(data1);
        do2.setData(data2);
    }

    public String[] getData(){
        return new String[] {do1.getData(),do2.getData()};
    }

}

  • DependentObjectOne.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> 依赖对象 </p>
 *
 * <pre> Created: 2018/5/27 下午7:15  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class DependentObjectOne {

    private String data;

    public void setData(String data){
        this.data = data;
    }

    public String getData(){
        return data;
    }

}

测试

  • Main.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.compositeEntity;

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/27 下午7:24  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class Main {

    public static void main(String[] args) {
        Client client = new Client();
        client.setData("Test", "Data");
        client.printData();
        client.setData("Second Test", "Data1");
        client.printData();
    }

}

  • 测试结果
Data: Test
Data: Data
Data: Second Test
Data: Data1

实现方式

UML & Code

UML

UML 图示如下

Code

代码地址

组合实体模式

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