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描述

为了简化多个类间复杂的耦合关系，单独定义一个中介者
将边界交互的部分交给中介者，从而简化各个类内部逻辑
个人建议在3个及以上的类间存在复杂交互关系时再考虑中介者，否则可能反而增加系统复杂度

基本使用

• 定义抽象业务对象（引用中介者）

public abstract class AbstractColleague {protected AbstractMediator mediator;public AbstractColleague(AbstractMediator _mediator) {this.mediator = _mediator;}
}

• 定义三个具体业务对象

public class ColleagueA extends AbstractColleague {public ColleagueA(AbstractMediator _mediator) {super(_mediator);}/*** 外部调a* @param a*/public void action(int a) {System.out.println("a..." + a);}public void action2() {System.out.println("a 内部业务");this.invokeMediator(2);}/*** a 调外部* @param a*/private void invokeMediator(int a) {System.out.println("a外部交互..." + a);mediator.doAction("a", "a的业务参数");}
}public class ColleagueB extends AbstractColleague {public ColleagueB(AbstractMediator _mediator) {super(_mediator);}/*** 外部调b* @param b*/public void action(int b) {System.out.println("b..." + b);}public void action2() {System.out.println("b 内部业务");this.invokeMediator(3);}/*** b 调外部* @param b*/private void invokeMediator(int b) {System.out.println("invokeMediator..." + b);mediator.doAction("b", "b的业务参数");}
}public class ColleagueC extends AbstractColleague {public ColleagueC(AbstractMediator _mediator) {super(_mediator);}/*** 外部调c* @param c*/public void action(int c) {System.out.println("c..." + c);}public void action2() {System.out.println("c 内部业务");this.invokeMediator(3);}/*** c 调外部* @param c*/private void invokeMediator(int c) {System.out.println("invokeMediator..." + c);mediator.doAction("c", "c的业务参数");}
}

• 定义提抽象中介者

public abstract class AbstractMediator {public abstract void doAction(String command, Object... param);
}

• 定义具体中介者（中介者要关联所有相关方，代替各方直接调用其他业务方）

public class MediatorAbc extends AbstractMediator {private ColleagueA colleagueA;private ColleagueB colleagueB;private ColleagueC colleagueC;public MediatorAbc() {this.colleagueA = new ColleagueA(this);this.colleagueB = new ColleagueB(this);this.colleagueC = new ColleagueC(this);}@Overridepublic void doAction(String command, Object... param) {switch (command) {case "a":// a -> 调用 b cthis.colleagueB.action(param.length);this.colleagueC.action(param.length);break;case "b":// b -> 调用 a cthis.colleagueA.action(param.length);this.colleagueC.action(param.length);break;case "c":// c -> 调用 a bthis.colleagueA.action(param.length);this.colleagueB.action(param.length);break;default:throw new RuntimeException();}}
}

使用

其实就是字面意思，将和其他模块交互的部分交给中介完成（由中介去沟通各方 这和现实中的中介如出一辙）

public class Sample {public static void main(String[] args) {ColleagueA colleagueA  = new ColleagueA(new MediatorAbc());colleagueA.action2();}
}