设计模式——中介者模式-CFANZ编程社区

模式介绍

中介者模式(Mediator Pattern)，用一个中介对象来封装一系列的对象交互。中介者使各个对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。
中介者模式属于行为型模式，使代码易于维护。
比如MVC模式，C(Controller控制器)是M(Model模型)和V(View视图)的中介者，在前后端交互时起到了中间人的作用

UML类图

类图解析：

Mediator就是抽象中介者，定义了同事对象到中介者对象的接口
Colleague是抽象同事类
ConcreteMediator具体的中介者对象，实现抽象方法，他需要知道所有的具体的同事类，即以一个集合来管理
HashMap,并接受某个同事对象消息，完成相应的任务
ConcreteColleague具体的同事类,会有很多，每个同事只知道自己的行为，而不了解其他同事类的行为(方法),
但是他们都依赖中介者对象

中介者模式案例

背景介绍:现代智能家居，根据用户需求制定智能家居相互间的联动效果：如在本案例中闹钟响起后，咖啡机会煮咖啡，并打开TV，观看热点新闻，咖啡煮好后，拉起窗帘并关闭TV...

Mediator抽象类（智能家居调控）

public abstract class Mediator {
   public abstract void Register(String colleagueName, Colleague colleague);

   public abstract void GetMessage(int stateChange, String colleagueName);

   public abstract void SendMessage();
}

Colleague(智能设备抽象类)

public abstract class Colleague {
   private Mediator mediator;
   public String name;

   public Colleague(Mediator mediator, String name) {

      this.mediator = mediator;
      this.name = name;

   }

   public Mediator GetMediator() {
      return this.mediator;
   }

   public abstract void SendMessage(int stateChange);
}

Mediator子类ConcreteMediator

public class ConcreteMediator extends Mediator {
   private HashMap<String, Colleague> colleagueMap;
   private HashMap<String, String> interMap;

   public ConcreteMediator() {
      colleagueMap = new HashMap<String, Colleague>();
      interMap = new HashMap<String, String>();
   }

   @Override
   public void Register(String colleagueName, Colleague colleague) {
      colleagueMap.put(colleagueName, colleague);

      // TODO Auto-generated method stub

      if (colleague instanceof Alarm) {
         interMap.put("Alarm", colleagueName);
      } else if (colleague instanceof CoffeeMachine) {
         interMap.put("CoffeeMachine", colleagueName);
      } else if (colleague instanceof TV) {
         interMap.put("TV", colleagueName);
      } else if (colleague instanceof Curtains) {
         interMap.put("Curtains", colleagueName);
      }

   }

   @Override
   public void GetMessage(int stateChange, String colleagueName) {
      if (colleagueMap.get(colleagueName) instanceof Alarm) {
         if (stateChange == 0) {
            ((CoffeeMachine) (colleagueMap.get(interMap
                  .get("CoffeeMachine")))).StartCoffee();
            ((TV) (colleagueMap.get(interMap.get("TV")))).StartTv();
         } else if (stateChange == 1) {
            ((TV) (colleagueMap.get(interMap.get("TV")))).StopTv();
         }

      } else if (colleagueMap.get(colleagueName) instanceof CoffeeMachine) {
         ((Curtains) (colleagueMap.get(interMap.get("Curtains")))).UpCurtains();

      } else if (colleagueMap.get(colleagueName) instanceof TV) {

      } else if (colleagueMap.get(colleagueName) instanceof Curtains) {

      }

   }

   @Override
   public void SendMessage() {
   }

}

Colleague子类Alarm、TV、CoffeeMachine、Curtains

public class Alarm extends Colleague {

   public Alarm(Mediator mediator, String name) {
      super(mediator, name);
      mediator.Register(name, this);
   }

   public void SendAlarm(int stateChange) {
      SendMessage(stateChange);
   }

   @Override
   public void SendMessage(int stateChange) {
      this.GetMediator().GetMessage(stateChange, this.name);
   }

}

public class TV extends Colleague {

   public TV(Mediator mediator, String name) {
      super(mediator, name);
      mediator.Register(name, this);
   }

   @Override
   public void SendMessage(int stateChange) {
      this.GetMediator().GetMessage(stateChange, this.name);
   }

   public void StartTv() {
      System.out.println("It's time to StartTv!");
   }

   public void StopTv() {
      System.out.println("StopTv!");
   }
}

public class CoffeeMachine extends Colleague {

   public CoffeeMachine(Mediator mediator, String name) {
      super(mediator, name);
      mediator.Register(name, this);
   }

   @Override
   public void SendMessage(int stateChange) {
      this.GetMediator().GetMessage(stateChange, this.name);
   }

   public void StartCoffee() {
      System.out.println("It's time to startcoffee!");
   }

   public void FinishCoffee() {
      System.out.println("After 5 minutes!");
      System.out.println("Coffee is ok!");
      SendMessage(0);
   }
}

public class Curtains extends Colleague {

   public Curtains(Mediator mediator, String name) {
      super(mediator, name);
      mediator.Register(name, this);
   }

   @Override
   public void SendMessage(int stateChange) {
      this.GetMediator().GetMessage(stateChange, this.name);
   }

   public void UpCurtains() {
      System.out.println("I am holding Up Curtains!");
   }

}

ClientTest测试类

public class ClientTest {
   public static void main(String[] args) {
      // 智能设备中介者
      Mediator mediator = new ConcreteMediator();

      // 添加智能设备到管中介中
      Alarm alarm = new Alarm(mediator, "alarm");
      CoffeeMachine coffeeMachine = new CoffeeMachine(mediator, "coffeeMachine");
      Curtains curtains = new Curtains(mediator, "curtains");
      TV tV = new TV(mediator, "TV");

      // 发送消息
      alarm.SendAlarm(0);
      coffeeMachine.FinishCoffee();
      alarm.SendAlarm(1);
   }
}

实现结果：