中介者模式
用一个中介对象来封装一系列的对象交互。中介者使各个对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。
中介者模式UML图
中介者模式代码
package com.roc.mediator;
/**
* 抽象中介者类
* @author liaowp
*
*/
public abstract class Mediator { public abstract void send(String message,Colleague colleague); }
package com.roc.mediator;
public class ConcreteMediator extends Mediator{
private Colleague1 colleague1;
private Colleague2 colleague2;
public void setColleague1(Colleague1 colleague1) {
this.colleague1 = colleague1;
}
public void setColleague2(Colleague2 colleague2) {
this.colleague2 = colleague2;
}
public void send(String message, Colleague colleague) {
if (colleague == colleague1) {
colleague2.Notify(message);
}else{
colleague1.Notify(message);
}
}
}
package com.roc.mediator;
/**
* 抽象同事类
* @author liaowp
*
*/
public abstract class Colleague { protected Mediator mediator; public Colleague(Mediator mediator){
this.mediator=mediator;
}
}
package com.roc.mediator;
public class Colleague1 extends Colleague{
public Colleague1(Mediator mediator) {
super(mediator);
}
public void send(String message){
mediator.send(message, this);
}
public void Notify(String message){
System.out.println("同事1得到消息:"+message);
}
}
package com.roc.mediator;
public class Colleague2 extends Colleague{
public Colleague2(Mediator mediator) {
super(mediator);
}
public void send(String message){
mediator.send(message, this);
}
public void Notify(String message){
System.out.println("同事2得到消息:"+message);
}
}
package com.roc.mediator;
/**
* 中介者模式
* @author liaowp
*
*/
public class Client { public static void main(String[] args) {
ConcreteMediator mediator=new ConcreteMediator();
Colleague1 colleague1=new Colleague1(mediator);
Colleague2 colleague2=new Colleague2(mediator);
mediator.setColleague1(colleague1);
mediator.setColleague2(colleague2);
colleague1.send("最近还好吗？");
colleague2.send("还不错");
} }
中介者模式适用场景
- 一组对象以定义良好但是复杂的方式进行通信。产生的相互依赖关系结构混乱且难以理解。
- 一个对象引用其他很多对象并且直接与这些对象通信,导致难以复用该对象。
- 想定制一个分布在多个类中的行为，而又不想生成太多的子类。
- 一般应用于一组对象以定义良好但是复杂的方式进行通信的场合。