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设计模式 - 行为型模式 - 中介者模式

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设计模式 - 行为型模式 - 中介者模式

设计模式

设计模式分为创建型模式、结构型模式和行为型模式。
创建型模式：创建对象。
结构型模式：把复杂结构分解为多个类，分解的是类本身（包括算法和属性）。
行为型模式：把复杂算法分解到多个类，分解的是算法。

UML

中介者模式

示例代码

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public class MediatorPattern {
    public static void main(String[] args) {
        Mediator mediator = new ConcreteMediator();
        Colleague colleague1 = new ConcreteColleague1();
        Colleague colleague2 = new ConcreteColleague2();
        mediator.register(colleague1);
        mediator.register(colleague2);
        colleague1.send();
        colleague2.send();
    }
}

abstract class Mediator {
    public abstract void register(Colleague colleague);
    public abstract void relay(Colleague colleague);
}

class ConcreteMediator extends Mediator {
    private List<Colleague> colleagues = new ArrayList<>();

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

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

abstract class Colleague {
    protected Mediator mediator;

    public void setMediator(Mediator mediator) {
        this.mediator = mediator;
    }

    public abstract void send();
    public abstract void receive();
}

class ConcreteColleague1 extends Colleague {
    @Override
    public void send() {
        System.out.println("ConcreteColleague1 send");
        mediator.relay(this);
    }

    @Override
    public void receive() {
        System.out.println("ConcreteColleague1 receive");
    }
}

class ConcreteColleague2 extends Colleague {
    @Override
    public void send() {
        System.out.println("ConcreteColleague2 send");
        mediator.relay(this);
    }

    @Override
    public void receive() {
        System.out.println("ConcreteColleague2 receive");
    }
}