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一、概述

       中介者模式（Mediator），用一个中介对象来封装一系列的对象交互 。中介者使个对象不需要显示的互相引用，使其耦合松散，而且可以独立的改变他们之间的交互。

二、UML图示

三、代码实现

1、抽象中介者

public abstract class Mediator {    public abstract void send(String message,Colleague colleague);}

2、抽象同事类

public abstract class Colleague {    protected Mediator mediator;    public Colleague(Mediator mediator) {        this.mediator = mediator;    }}

3、具体同事类

public class ConcreteColleagueA extends Colleague {    public ConcreteColleagueA(Mediator mediator) {        super(mediator);    }    public void send(String message){        mediator.send(message,this);    }    public void notifyMessage(String message){        System.out.println("同事A收到信息:"+message);    }}public class ConcreteColleagueB extends Colleague {    public ConcreteColleagueB(Mediator mediator) {        super(mediator);    }    public void send(String message){        mediator.send(message,this);    }    public void notifyMessage(String message){        System.out.println("同事B收到的信息:"+message);    }}

4、具体中介者

public class ConcreteMediator extends Mediator {    private ConcreteColleagueA concreteColleagueA;    private ConcreteColleagueB concreteColleagueB;    @Override    public void send(String message, Colleague colleague) {        if(colleague == concreteColleagueA){            concreteColleagueB.notifyMessage(message);        }else {            concreteColleagueA.notifyMessage(message);        }    }    public ConcreteColleagueA getConcreteColleagueA() {        return concreteColleagueA;    }    public void setConcreteColleagueA(ConcreteColleagueA concreteColleagueA) {        this.concreteColleagueA = concreteColleagueA;    }    public ConcreteColleagueB getConcreteColleagueB() {        return concreteColleagueB;    }    public void setConcreteColleagueB(ConcreteColleagueB concreteColleagueB) {        this.concreteColleagueB = concreteColleagueB;    }}

5、测试类

public class Test {    public static void main(String[] args) {        ConcreteMediator concreteMediator = new ConcreteMediator();        ConcreteColleagueA concreteColleagueA = new ConcreteColleagueA(concreteMediator);        ConcreteColleagueB concreteColleagueB = new ConcreteColleagueB(concreteMediator);        concreteMediator.setConcreteColleagueA(concreteColleagueA);        concreteMediator.setConcreteColleagueB(concreteColleagueB);        concreteColleagueA.send("吃饭了吗？");        concreteColleagueB.send("没有呢，你要请客吗？");    }}输出：同事B收到的信息:吃饭了吗？同事A收到信息:没有呢，你要请客吗？

注：参考文献《大话设计模式》程杰著。