二十三种设计模式(第十八种)-----中介者模式(Mediator)

二十三种设计模式(第十八种)-----中介者模式(Mediator)

尚硅谷视频连接https://www.bilibili.com/video/BV1G4411c7N4?from=search&seid=11487053970269878470

1. 中介者模式：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示地相互引用，从而使其耦合松散，而且可以独立地改变他们之间的交互
2. 中介者模式属于行为模式，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

类图

需求

需求类图

代码

1.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);
}

2.具体同事

public class Alarm extends Colleague {

    public Alarm(Mediator mediator,String name) {
        super(mediator,name);
        //在创建Alarm同事对象时，将自己放入到ConcreteMediator对象中
        mediator.registor(name,this);
    }

    public void sendAlarm(int stateChange){
        sendMessage(stateChange);
    }

    @Override
    public void sendMessage(int stateChange) {
        //调用的中介者对象的getMessage
        this.getMediator().getMessage(stateChange,this.name);
    }

    public void startAlarm(){
        System.out.println("打开闹钟...");
    }

    public void stopAlarm(){
        System.out.println("关闭闹钟...");
    }
}
//======================================================
public class CoffeeMachine extends Colleague {
    public CoffeeMachine(Mediator mediator, String name) {
        super(mediator, name);
        mediator.registor(name,this);
    }

    public void openCoffeeMachine(int stateChange){
        sendMessage(stateChange);
    }

    @Override
    public void sendMessage(int stateChange) {
        //调用的中介者对象的getMessage
        this.getMediator().getMessage(stateChange,this.name);
    }

    public void startCoffee(){
        System.out.println("打开咖啡机...");
    }

    public void stopCoffee(){
        System.out.println("关闭咖啡机...");
    }
}
//======================================================
public class Curtains extends Colleague {
    public Curtains(Mediator mediator, String name) {
        super(mediator, name);
        mediator.registor(name,this);
    }

    public void openCurtains(int stateChange){
        sendMessage(stateChange);
    }

    @Override
    public void sendMessage(int stateChange) {
        //调用的中介者对象的getMessage
        this.getMediator().getMessage(stateChange,this.name);
    }

    public void upCurtain(){
        System.out.println("挂起窗帘...");
    }

    public void offCurtain(){
        System.out.println("关闭窗帘...");
    }
}
//==========================================================
public class TV extends Colleague {
    public TV(Mediator mediator, String name) {
        super(mediator, name);
        mediator.registor(name,this);
    }

    public void openTV(int stateChange){
        sendMessage(stateChange);
    }

    @Override
    public void sendMessage(int stateChange) {
        //调用的中介者对象的getMessage
        this.getMediator().getMessage(stateChange,this.name);
    }

    public  void startTv(){
        System.out.println("打开电视...");
    }

    public void stopTv(){
        System.out.println("关闭电视...");
    }
}

3.中介者抽象类

public abstract class Mediator {
    //将中介者对象，加入到集合
    public abstract void registor(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();
}

4.具体中介者

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<>();
        interMap = new HashMap<>();
    }

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

        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.根据得到的消息，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) {
        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) {
                ((CoffeeMachine) colleagueMap.get(interMap.get("CoffeeMachine"))).startCoffee();
            }
        } else if (colleagueMap.get(colleagueName) instanceof CoffeeMachine) {
            ((TV) colleagueMap.get(interMap.get("TV"))).startTv();
        } else if (colleagueMap.get(colleagueName) instanceof TV) {
            ((TV) colleagueMap.get(interMap.get("TV"))).stopTv();
        } else if (colleagueMap.get(colleagueName) instanceof Curtains) {
            ((CoffeeMachine) colleagueMap.get(interMap.get("CoffeeMachine"))).stopCoffee();
        }
    }

    @Override
    public void sendMessage() {

    }
}

5.客户端

public class Client {
    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CoffeeMachine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);
    }
}