中介者模式

Posted 2021-03-12 yfy-

一、定义

中介者模式（Mediator)，用一个中介对象来封装一系列的对象交互。中介者使各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。

二、示例代码

public abstract class Mediator {
    public abstract void send(String message,Colleague colleague);
}

public class ConcreteMediator extends Mediator {
    private ConcreteColleague1 concreteColleague1;
    private ConcreteColleague2 concreteColleague2;

    public void setConcreteColleague1(ConcreteColleague1 concreteColleague1) {
        this.concreteColleague1 = concreteColleague1;
    }

    public void setConcreteColleague2(ConcreteColleague2 concreteColleague2) {
        this.concreteColleague2 = concreteColleague2;
    }

    @Override
    public void send(String message, Colleague colleague) {
        if (colleague==concreteColleague1){
            concreteColleague2.inform(message);
        }
        else {
            concreteColleague1.inform(message);
        }
    }
}

public class ConcreteColleague1 extends Colleague {

    public ConcreteColleague1(Mediator mediator) {
        super(mediator);
    }
    public void send(String message){
        mediator.send(message,this);
    }
    public void inform(String message)
    {
        System.out.println("同事1得到消息"+message);
    }
}

public class ConcreteColleague2 extends Colleague {
    public ConcreteColleague2(Mediator mediator) {
        super(mediator);
    }
    public void send(String message){
        mediator.send(message,this);
    }
    public void inform(String message)
    {
        System.out.println("同事2得到消息"+message);
    }
}

public abstract class Colleague {
    protected Mediator mediator;

    public Colleague(Mediator mediator) {
        this.mediator = mediator;
    }
}

public class Client {
    public static void main(String[] args) {
        ConcreteMediator mediator=new ConcreteMediator();
        ConcreteColleague1 concreteColleague1=new ConcreteColleague1(mediator);
        ConcreteColleague2 concreteColleague2=new ConcreteColleague2(mediator);
        mediator.setConcreteColleague1(concreteColleague1);
        mediator.setConcreteColleague2(concreteColleague2);

        mediator.send("hello",concreteColleague1);
        mediator.send("hi",concreteColleague2);
    }
}