中介者模式(Mediator)

中介者模式也是用来降低类类之间的耦合的,因为如果类类之间有依赖关系的话,不利于功能的拓展和维护,因为只要修改一个对象,其它关联的对象都得进行修改。如果使用中介者模式,只需关心和Mediator类的关系,具体类类之间的关系及调度交给Mediator就行,这有点像spring容器的作用。先看看图:


User类统一接口,User1和User2分别是不同的对象,二者之间有关联,如果不采用中介者模式,则需要二者相互持有引用,这样二者的耦合度很高,为了解耦,引入了Mediator类,提供统一接口,MyMediator为其实现类,里面持有User1和User2的实例,用来实现对User1和User2的控制。这样User1和User2两个对象相互独立,他们只需要保持好和Mediator之间的关系就行,剩下的全由MyMediator类来维护!基本实现:

 

[java] view plaincopy
public interface Mediator {
public void createMediator();
public void workAll();
}
[java] view plaincopy
public class MyMediator implements Mediator {

private User user1;
private User user2;

public User getUser1() {
return user1;
}

public User getUser2() {
return user2;
}

@Override
public void createMediator() {
user1 = new User1(this);
user2 = new User2(this);
}

@Override
public void workAll() {
user1.work();
user2.work();
}
}
[java] view plaincopy
public abstract class User {

private Mediator mediator;

public Mediator getMediator(){
return mediator;
}

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

public abstract void work();
}
[java] view plaincopy
public class User1 extends User {

public User1(Mediator mediator){
super(mediator);
}

@Override
public void work() {
System.out.println("user1 exe!");
}
}
[java] view plaincopy
public class User2 extends User {

public User2(Mediator mediator){
super(mediator);
}

@Override
public void work() {
System.out.println("user2 exe!");
}
}
测试类:

[java] view plaincopy
public class Test {

public static void main(String[] args) {
Mediator mediator = new MyMediator();
mediator.createMediator();
mediator.workAll();
}
}
输出:

user1 exe!
user2 exe!

posted on 2017-11-21 18:02  公子扶胸  阅读(246)  评论(0编辑  收藏  举报