12种行为模式 之8 MEDIATOR 调停者模式

8、MEDIATOR

调停者模式：

没使用调停者模式 ： 一个过度耦合的系统 ： 网状结构



使用调停者模式 后 ： 以调停者为 中心的星状结构




/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:24:28
* <p/>
* note: 调停者角色
*/
abstract public class Mediator {

    /**
     * 事件方法
     * @param c
     */
    public abstract void colleagueChanged(Colleague c);

}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:24:39
* <p/>
* note: 具体调停者角色
*/
public class ConcreteMediator extends Mediator {
    private Colleague1 colleague1;
    private Colleague2 colleague2;

    /**
     * 将所有同事 实例化
     */
    public void createConcreteMediator() {
        colleague1 = new Colleague1(this);
        colleague2 = new Colleague2(this);
    }

    /**
     * 事件方法
     * @param c
     */
    public void colleagueChanged(Colleague c ) {
        colleague1.action();
        colleague2.action();
    }

    public Colleague1 getColleague1() {
        return colleague1 ;
    }

    public Colleague2 getColleague2() {
        return colleague2 ;
    }
}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:24:50
* <p/>
* note: 抽象同事角色
*       每个同事对象 仅知道调停者
*       而不知道其他同事对象
*/
public abstract class Colleague {
    private Mediator mediator;

    public Colleague(Mediator m) {
        mediator = m;
    }

    /**
     * 当前同时对象发生变化时，通知调停者
     */
    public void change() {
        mediator.colleagueChanged(this);
    }

    /**
     * 行动方法，一个同事对象在得知其他同事对象有变化时
     * 会执行此方法
     */
    public abstract void action();

    public Mediator getMediator() {
        return mediator;
    }
}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:25:00
* <p/>
* note: 具体同事角色
*/
public class Colleague1 extends Colleague {
    public Colleague1(Mediator m) {
        super(m);
    }

    public void action() {
        System.out.println("This is an action from Colleague 1");
    }
}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:25:10
* <p/>
* note: 具体同事角色
*/
public class Colleague2 extends Colleague {
    public Colleague2(Mediator m) {
        super( m );
    }

    public void action() {
        System.out.println("This is an action from Colleague 2");
    }
}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:25:20
* <p/>
* note: 具体同事角色
*/
public class Colleague3 extends Colleague {
    public Colleague3(Mediator m) {
        super( m );
    }

    public void action() {
        System.out.println("This is an action from Colleague 3");
    }
}

/**
* User: [e-mail]
* Date: 2008-12-9 Time: 15:34:30
* <p/>
* note: 客户端角色
*/
public class Client {

    public static void main(String args[]) {
        ConcreteMediator mediator = new ConcreteMediator();
        mediator.createConcreteMediator();

        Colleague c1 = new Colleague1(mediator);
        Colleague c2 = new Colleague2(mediator);

        mediator.colleagueChanged(c1);
    }
}