利用Observable、Observer实现观察者模式

import java.util.Observable;import java.util.Observer;public class Observe {public static  void mian(String args[]){int a=10;BeingWatched watched=new BeingWatched();Watcher1 watcher1=new Watcher1();Watcher2 watcher2=new Watcher2();watched.addObserver(watcher1);watched.addObserver(watcher2);watched.method(a);}}class BeingWatched extends Observable{public void method(int x){for(;x>=0;x--){this.setChanged();this.notifyObservers(x);//自动调用Observer中 update方法}}}class Watcher1 implements Observer{@Overridepublic void update(Observable o, Object arg){System.out.println((Integer)arg);}}class Watcher2 implements Observer{@Overridepublic void update(Observable o, Object arg){Integer j=(Integer)arg;if(j<=5)System.out.println(j);}}