一、模式定义:
用一个中介者对象来封装一系列的对象交互。中介者使各对象不需要显式的相互引用，从而使其耦合松散，而且可以独立的改变他们之间的交互。
二、结构图
1) 抽象中介者：定义同事（Colleague）对象到中介者（Mediatior）对象的接口，通常是一个事件方法。
2) 具体中介者：具体中介者实现抽象中介者声明的方法。知晓所有的具体同事类，从具体同事接收消息向另外的具体同事类发送命令。
3) 抽象同事类：定义中介者到同事对象的接口，同事对象只知道中介者而不知道其他同事对象。
三、一个例子
import java.util.ArrayList;abstract class AbstractMediator{
public abstract void register(AbstractColleague ac);
public abstract void ColleagueChanged(AbstractColleague ac);
}
abstract class AbstractColleague{
private AbstractMediator med;
public AbstractColleague(AbstractMediator mediator){
this.med=mediator;
}
public abstract void action();
public void changed(){
med.ColleagueChanged(this);
}
}
class ConcreteMediator extends AbstractMediator{
private ArrayList<AbstractColleague> colleagueList=new ArrayList<AbstractColleague>();
public void register(AbstractColleague ac) {
colleagueList.add(ac);
}
public void ColleagueChanged(AbstractColleague ac) {
for(int i=0;i<colleagueList.size();i++){
if(colleagueList.get(i)!=ac){
colleagueList.get(i).action();
}
}
}
}
class ConcreteColleagueA extends AbstractColleague{
public ConcreteColleagueA(AbstractMediator mediator){
super(mediator);
mediator.register(this);
}
public void action() {
System.out.println("AAAAAAAAAAAAAAA");
}
}
class ConcreteColleagueC extends AbstractColleague{
public ConcreteColleagueC(AbstractMediator mediator){
super(mediator);
mediator.register(this);
}
public void action() {
System.out.println("CCCCCCCCCCCCCCC");
}
}
class ConcreteColleagueB extends AbstractColleague{
public ConcreteColleagueB(AbstractMediator mediator){
super(mediator);
mediator.register(this);
}
public void action() {
System.out.println("BBBBBBBBBBBBBBB");
}
}
class test{
public static void main(String[] args){
AbstractMediator mediator=new ConcreteMediator();
AbstractColleague colleagueA=new ConcreteColleagueA(mediator);
AbstractColleague colleagueB=new ConcreteColleagueB(mediator);
AbstractColleague colleagueC=new ConcreteColleagueC(mediator);
colleagueA.changed();
colleagueB.changed();
colleagueC.changed();
}
}