调停者模式

调停者本质是门面模式另一个面，门面模式相当于从外面看，调停者相当于从内部看，都是把原来复杂的类联系转为星形。

image.png image.png

第一步，新建一个抽象类作为星形的核心类，跟周边类打交道,同时被打交道的周边类也抽象一个

public abstract class Mediator {

    //协调动作，谁通知中介者，中介者在通知第三方干活
    abstract void coordinate(String userName, String msg, Colleague colleague) ;

}

public  abstract class Colleague {
    protected String name;
    protected Mediator mediator;

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

    public void getMsg (String userName, String msg){
        System.out.println("【"+this.name+"】收到"+"【"+userName+"】协调任务：["+msg+"]");
    }
    public void sendMsg (String name,String msg,Colleague colleague){
        System.out.println("【"+name+"】发起协调任务："+ msg);
        mediator.coordinate(name,msg,colleague);
    }

}

上面两个抽象类你中有我，我中有你，Mediator 严格来讲必须在Colleague 中出现，所以用构造注入，而Colleague 在Mediator 中是多个存在，可以不是全部拥有，可以用set注入。

第二步添加几个抽象类的实现

public class AColleagueImpl extends  Colleague{

    public AColleagueImpl(String name, Mediator mediator) {
        super(name, mediator);
    }
}
public class BColleagueImpl extends  Colleague{

    public BColleagueImpl(String name, Mediator mediator) {
        super(name, mediator);
    }
}

public class CColleagueImpl extends  Colleague{

    public CColleagueImpl(String name, Mediator mediator) {
        super(name, mediator);
    }
}

public class MediatorImpl extends Mediator{

    @Override
    void coordinate(String userName, String msg, Colleague colleague) {
        System.out.println("中介者接收【"+userName+"】的协调任务：" + msg);
        System.out.println("经理转发【"+userName+"】协调任务,@【"+colleague.name+"】");
        colleague.getMsg(userName,msg);
    }
}

调停者本质就是封装然后转发请求

public class Client {
    public static void main(String[] args) {
        Mediator mediator = new MediatorImpl() ;
        Colleague employeeA = new AColleagueImpl("张三",mediator) ;
        Colleague employeeB = new BColleagueImpl("李四",mediator) ;
        employeeA.sendMsg(employeeA.name,"需要产品文档",employeeB);

    }
}
\\console
\*【张三】发起协调任务：需要产品文档
中介者接收【张三】的协调任务：需要产品文档
经理转发【张三】协调任务,@【李四】
【李四】收到【张三】协调任务：[需要产品文档]*\