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中介者模式
UML
解释说明
- 中介者模式：用一个中介对象来封装一系列的对象交互。中介者使各对象不需要显式地相互引用，从而使其耦合降低，并且可以独立地改变他们之间的交互。
- 注意：中介者会使交互的复杂性转变成中介者的复杂性。
- 中介者模式一般应用于一组对象以良好但是复杂的方式进行通信的场合，以及想定制一个分布在多个类中的行为，但是又不想生成太多的子类的场合。
代码实现
- Colleague.class
package learn21;
public abstract class Colleague {
protected Mediator mediator;
public Colleague(Mediator mediator) {
this.mediator = mediator;
}
}
- Mediator.class
package learn21;
public abstract class Mediator {
public abstract void send(String msg, Colleague colleague);
}
- ConcreteMediator.class
package learn21;
public class ConcreteMediator extends Mediator {
private ConcreteColleague1 concreteColleague1;
private ConcreteColleague2 concreteColleague2;
public void setConcreteColleague1(ConcreteColleague1 concreteColleague1) {
this.concreteColleague1 = concreteColleague1;
}
public void setConcreteColleague2(ConcreteColleague2 concreteColleague2) {
this.concreteColleague2 = concreteColleague2;
}
@Override
public void send(String msg, Colleague colleague) {
if (colleague == concreteColleague1) {
concreteColleague2.notify(msg);
} else {
concreteColleague1.notify(msg);
}
}
}
- ConcreteColleague1.class
package learn21;
public class ConcreteColleague1 extends Colleague {
public ConcreteColleague1(Mediator mediator) {
super(mediator);
}
public void send(String msg) {
mediator.send(msg, this);
}
public void notify(String msg) {
System.out.println("ConcreteColleague1收到：" + msg);
}
}
- ConcreteColleague2.class
package learn21;
public class ConcreteColleague2 extends Colleague {
public ConcreteColleague2(Mediator mediator) {
super(mediator);
}
public void send(String msg) {
mediator.send(msg, this);
}
public void notify(String msg) {
System.out.println("ConcreteColleague2收到：" + msg);
}
}
- Main.class
import learn21.*;
public class Main {
public static void main(String[] args) throws Exception {
ConcreteMediator m = new ConcreteMediator();
ConcreteColleague1 c1 = new ConcreteColleague1(m);
ConcreteColleague2 c2 = new ConcreteColleague2(m);
m.setConcreteColleague1(c1);
m.setConcreteColleague2(c2);
c1.send("我是c1!");
c2.send("我是c2!");
}
}
参考资料
- 大话设计模式