行为型模式 --- 中介者模式

package study.org;

import java.util.ArrayList;
import java.util.List;

// 测试类
public class Demo {
    public static void main(String[] args) {
        Mediator md = new ConcreteMediator();
        
        Colleague c1 = new ConcreteColleague1();
        Colleague c2 = new ConcreteColleague2();
        
        md.register(c1);
        md.register(c2);
        
        c1.send();
        c2.send();
    }
}

// 中介者
abstract class Mediator {
    public abstract void register(Colleague colleague);

    public abstract void relay(Colleague cl); // 转发
}

class ConcreteMediator extends Mediator {

    private List<Colleague> colleagues = new ArrayList<Colleague>();

    @Override
    public void register(Colleague colleague) {
        if (!colleagues.contains(colleague)) {
            colleagues.add(colleague);
            colleague.setMedium(this);
        }
    }

    @Override
    public void relay(Colleague cl) {
        for (Colleague ob : colleagues) {
            if (!ob.equals(cl)) {
                ((Colleague) ob).receive();
            }
        }
    }
}

// 抽象同事类
abstract class Colleague {
    protected Mediator mediator;

    protected void setMedium(Mediator mediator) {
        this.mediator = mediator;
    }

    public abstract void receive();

    public abstract void send();
}

//具体同事类1
class ConcreteColleague1 extends Colleague {
    public void receive() {
        System.out.println("具体同事类1收到请求.");
    }

    public void send() {
        System.out.println("具体同事类1发出请求.");
        mediator.relay(this);
    }
}

//具体同事类2
class ConcreteColleague2 extends Colleague {
    public void receive() {
        System.out.println("具体同事类2收到请求.");
    }

    public void send() {
        System.out.println("具体同事类2发出请求.");
        mediator.relay(this);
    }
}