设计模式-行为型模式-中介者模式

谁践踏了优雅 2023-07-04 04:50 41阅读 0赞

**中介者模式基本介绍**

1) 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  
2) 中介者模式属于行为型模式，使代码易于维护  
3) 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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE1MTQwODQx_size_16_color_FFFFFF_t_70][]

对原理 类 图的说明- - 即( ( 中介者模式的角色及职 责)  
1) Mediator 就是抽象中介者,定义了同事对象到中介者对象的接口  
2) Colleague 是抽象同事类  
3) 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,  
 中介者模式 应例 用实例- 智能家

//具体的同事类
    public class Alarm extends Colleague {
    
    	//构造器
    	public Alarm(Mediator mediator, String name) {
    		super(mediator, name);
    		// TODO Auto-generated constructor stub
    		//在创建Alarm 同事对象时，将自己放入到ConcreteMediator 对象中[集合]
    		mediator.Register(name, this);
    	}
    
    	public void SendAlarm(int stateChange) {
    		SendMessage(stateChange);
    	}
    
    	@Override
    	public void SendMessage(int stateChange) {
    		// TODO Auto-generated method stub
    		//调用的中介者对象的getMessage
    		this.GetMediator().GetMessage(stateChange, this.name);
    	}
    }
    public class CoffeeMachine extends Colleague {
    
    	public CoffeeMachine(Mediator mediator, String name) {
    		super(mediator, name);
    		// TODO Auto-generated constructor stub
    		mediator.Register(name, this);
    	}
    
    	@Override
    	public void SendMessage(int stateChange) {
    		// TODO Auto-generated method stub
    		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);
    	}
    }
    //同事抽象类
    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);
    }
    //具体的中介者类
    public class ConcreteMediator extends Mediator {
    	//集合，放入所有的同事对象
    	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) {
    		// TODO Auto-generated method stub
    		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);
    		}
    
    	}
    
    	//具体中介者的核心方法
    	//1. 根据得到消息，完成对应任务
    	//2. 中介者在这个方法，协调各个具体的同事对象，完成任务
    	@Override
    	public void GetMessage(int stateChange, String colleagueName) {
    		// TODO Auto-generated method stub
    
    		//处理闹钟发出的消息
    		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) {//如果TV发现消息
    
    		} else if (colleagueMap.get(colleagueName) instanceof Curtains) {
    			//如果是以窗帘发出的消息，这里处理...
    		}
    
    	}
    
    	@Override
    	public void SendMessage() {
    		// TODO Auto-generated method stub
    	}
    }
    public class Curtains extends Colleague {
    
    	public Curtains(Mediator mediator, String name) {
    		super(mediator, name);
    		// TODO Auto-generated constructor stub
    		mediator.Register(name, this);
    	}
    
    	@Override
    	public void SendMessage(int stateChange) {
    		// TODO Auto-generated method stub
    		this.GetMediator().GetMessage(stateChange, this.name);
    	}
    	public void UpCurtains() {
    		System.out.println("I am holding Up Curtains!");
    	}
    }
    public abstract class Mediator {
    	//将给中介者对象，加入到集合中
    	public abstract void Register(String colleagueName, Colleague colleague);
    
    	//接收消息, 具体的同事对象发出
    	public abstract void GetMessage(int stateChange, String colleagueName);
    
    	public abstract void SendMessage();
    }
    public class TV extends Colleague {
    
    	public TV(Mediator mediator, String name) {
    		super(mediator, name);
    		// TODO Auto-generated constructor stub
    		mediator.Register(name, this);
    	}
    
    	@Override
    	public void SendMessage(int stateChange) {
    		// TODO Auto-generated method stub
    		this.GetMediator().GetMessage(stateChange, this.name);
    	}
    
    	public void StartTv() {
    		// TODO Auto-generated method stub
    		System.out.println("It's time to StartTv!");
    	}
    
    	public void StopTv() {
    		// TODO Auto-generated method stub
    		System.out.println("StopTv!");
    	}
    }
    public class ClientTest {
    
    	public static void main(String[] args) {
    		//创建一个中介者对象
    		Mediator mediator = new ConcreteMediator();
    		//创建Alarm 并且加入到  ConcreteMediator 对象的HashMap
    		Alarm alarm = new Alarm(mediator, "alarm");
    		//创建了CoffeeMachine 对象，并  且加入到  ConcreteMediator 对象的HashMap
    		CoffeeMachine coffeeMachine = new CoffeeMachine(mediator,
    				"coffeeMachine");
    		//创建 Curtains , 并  且加入到  ConcreteMediator 对象的HashMap
    		Curtains curtains = new Curtains(mediator, "curtains");
    		TV tV = new TV(mediator, "TV");
    		//让闹钟发出消息
    		alarm.SendAlarm(0);
    		coffeeMachine.FinishCoffee();
    		alarm.SendAlarm(1);
    	}
    
    }

中介者模式的注意事项和细节  
1) 多个类相互耦合，会形成网状结构, 使用中介者模式将网状结构分离为星型结构，进行解耦  
2) 减少类间依赖，降低了耦合，符合迪米特原则  
3) 中介者承担了较多的责任，一旦中介者出现了问题，整个系统就会受到影响  
4) 如果设计不当，中介者对象本身变得过于复杂，这点在实际使用时，要特别注意

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