中介者模式，又称为调停者模式或调解者模式

１．中介者模式结构图

2. 示例代码

   //　抽象中介类
   public abstract class Mediator {
   
       protected ConcreteColleagueA concreteColleagueA;
   
       protected ConcreteColleagueB concreteColleagueB;
   
       public void setConcreteColleagueA(ConcreteColleagueA concreteColleagueA) {
           this.concreteColleagueA = concreteColleagueA;
       }
   
       public void setConcreteColleagueB(ConcreteColleagueB concreteColleagueB) {
           this.concreteColleagueB = concreteColleagueB;
       }
   
       public abstract void methodA();
   
       public abstract void methodB();
   }
   
   //　具体中介类
   public class ConcreteMediator extends Mediator{
   
       public void methodA(){
           concreteColleagueB.doWorkB();
       }
   
       public void methodB(){
           concreteColleagueA.doWorkA();
       }
   }
   
   
   // 抽象同事类
   public abstract class Colleague {
   
       protected Mediator mediator;
   
       public Colleague(Mediator mediator) {
           this.mediator = mediator;
       }
   }
   
   //　具体同事类Ａ
   public class ConcreteColleagueA extends Colleague{
   
       public ConcreteColleagueA(Mediator mediator) {
           super(mediator);
       }
   
       public void selfMethodA(){
           mediator.methodA();
       }
   
       public void doWorkA(){
           System.out.println("具体处理对象A开始处理问题");
       }
   }
   
   //　具体同事类Ｂ
   public class ConcreteColleagueB extends Colleague{
   
       public ConcreteColleagueB(Mediator mediator) {
           super(mediator);
       }
   
       public void selfMethodB(){
           mediator.methodB();
       }
   
       public void doWorkB(){
           System.out.println("具体处理对象B开始处理问题");
       }
   }
   
   // 测试类
   public class MediatorTest {
   
       public static void main(String[] args) {
           ConcreteMediator mediator = new ConcreteMediator();
           ConcreteColleagueA colleagueA = new ConcreteColleagueA(mediator);
           ConcreteColleagueB colleagueB = new ConcreteColleagueB(mediator);
           mediator.setConcreteColleagueA(colleagueA);
           mediator.setConcreteColleagueB(colleagueB);
   
           colleagueA.selfMethodA();
       }
   }
   
   

   3. 总结：

      优点：由多对多关系转化为一对多，降低了类间的耦合，符合迪米特法则；

      缺点：当同事类复杂较多时，中介者就会变得臃肿且不易维护．