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1. 定义
又叫调停者模式。中介者包含了整个系统的控制逻辑，包装了对象之间相互作用的方式，使得这些对象（同事）不必相互明显引用。当这些对象中的某些对象之间的相互作用发生改变时，不会立即影响到其他对象（同事）之间的相互作用。从而保证这些相互作用可以彼此独立地变化。
2. 使用
- 抽象中介者：定义出连接同事对象的接口和业务方法
- 具体中介者：连接所有的具体同事类，并负责协调各同事对象的交互关系。
- 抽象同事类：定义出连接中介者的接口
- 具体同事类：实现自己的业务，在需要与其他同事通信的时候，与中介者通信
package MediatorPattern;
/**
* 抽象中介者
*/
public interface Mediator {
//中介者业务
public void changed(Colleague colleague);
}
package MediatorPattern;
/**
* 具体中介者
*/
public class ConcreteMediator implements Mediator {
private ColleagueA a;
private ColleagueB b;
public void setA(ColleagueA a) {
this.a = a;
}
public void setB(ColleagueB b) {
this.b = b;
}
@Override
public void changed(Colleague colleague) {
if (colleague instanceof ColleagueA){
b.receive();
}
else if (colleague instanceof ColleagueB){
a.receive();
}
}
}
package MediatorPattern;
/**
* 抽象同事
*/
public abstract class Colleague {
private Mediator mediator;
public Colleague(Mediator mediator) {
this.mediator = mediator;
}
public Mediator getMediator() {
return mediator;
}
}
package MediatorPattern;
/**
* 具体同事
*/
public class ColleagueA extends Colleague {
private String name;
public ColleagueA(Mediator mediator,String name) {
super(mediator);
this.name = name;
}
public void send() {
System.out.println(this+"请求数据");
getMediator().changed(this);
}
public void receive(){
System.out.println(this+"收到数据");
}
@Override
public String toString() {
return "ColleagueA{" +
"name='" + name + '\'' +
'}';
}
}
package MediatorPattern;
/**
* 具体同事
*/
public class ColleagueB extends Colleague {
private String name;
public ColleagueB(Mediator mediator,String name) {
super(mediator);
this.name = name;
}
public void send() {
System.out.println(this+"请求数据");
getMediator().changed(this);
}
public void receive(){
System.out.println(this+"收到数据");
}
@Override
public String toString() {
return "ColleagueB{" +
"name='" + name + '\'' +
'}';
}
}
package MediatorPattern;
public class Test {
public static void main(String[] args) {
ConcreteMediator mediator = new ConcreteMediator();
ColleagueA a = new ColleagueA(mediator,"A");
ColleagueB b = new ColleagueB(mediator,"B");
mediator.setA(a);
mediator.setB(b);
a.send();
b.send();
}
}
3. 特点
- 将对象解耦，增加复用性
- 集中控制逻辑
- 减少对象之间的消息传递
- 中介者可能过于复杂