JAVA-设计模式之中介者模式

package caosc.javaModel.Mediator;

public abstract class Colleague {
protected Mediator mediator;

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

public abstract void send(String message);
}

package caosc.javaModel.Mediator;

public abstract class Mediator {
public abstract void sendMessage(Colleague colleague,String message);
}

package caosc.javaModel.Mediator;

public class ConcreteMediator extends Mediator {
ConcreteColleague1 cc1;
ConcreteColleague2 cc2;

public ConcreteColleague1 getCc1() {
return cc1;
}

public void setCc1(ConcreteColleague1 cc1) {
this.cc1 = cc1;
}

public ConcreteColleague2 getCc2() {
return cc2;
}

public void setCc2(ConcreteColleague2 cc2) {
this.cc2 = cc2;
}

@Override
public void sendMessage(Colleague colleague, String message) {
if(colleague==cc1){
cc1.nodifyMessage(message);
}else{
cc2.nodifyMessage(message);
}
}

}

package caosc.javaModel.Mediator;

public class ConcreteColleague1 extends Colleague {

public ConcreteColleague1(Mediator mediator) {
super(mediator);
}

public void nodifyMessage(String message){
System.out.println(message);
}

@Override
public void send(String message) {
mediator.sendMessage(this, message);
};
}

package caosc.javaModel.Mediator;

public class ConcreteColleague2 extends Colleague {

public ConcreteColleague2(Mediator mediator) {
super(mediator);
}

public void nodifyMessage(String message){
System.out.println(message);
}

@Override
public void send(String message) {
mediator.sendMessage(this, message);
};
}

package caosc.javaModel.Mediator;

public class MediatorTest {

public static void main(String[] args) {
ConcreteMediator m = new ConcreteMediator();
ConcreteColleague1 cc1 = new ConcreteColleague1(m);
ConcreteColleague2 cc2 = new ConcreteColleague2(m);
m.cc1 = cc1;
m.cc2 = cc2;
cc1.send("今年加工资了吗？");
cc2.send("没有呢！");

}

}

使用场合：

1、由于把对象如何协作进行抽象，将中介作为一个独立的概念并将其封装到一个对象中，这样关注的对象就是对象各自本身的行为转到他们中间的交互上来，站在一个宏观的角度去看待系统

2、Mediator的出现，减少了各个Colleague的耦合，可以独立的改变和复用各个Colleague,Mediator

3、缺点是由于ConcreteMediator的集中处理,于是把交换复杂性变成交互者复杂性，所以ConcreteMediator比任何一个ConcreteColleagueX都复杂；