JDK观察者模式实现Observer Observable

JDK提供了观察者模式的实现类java.util.Observer,java.util.Observable.
java.util.Observer为观察者。
java.util.Observable观察物。

1.观察物

package observer;
import java.util.Observable;
public class Publisher extends Observable {
	private String magazineName;
	public String getMagazineName() {
		return magazineName;
	}
	public void publish(String magazineName) {
		this.magazineName = magazineName;
		setChanged();// set the changed signal
		notifyObservers();// notify all the observers
	}
}

2.观察者

package observer;
import java.util.Observable;
import java.util.Observer;
public class Reader implements Observer {
	// when the observable changed , 
	// it will notify all the observers and this method will be invoke
	@Override
	public void update(Observable o, Object arg) {
		if(o instanceof Publisher){
			Publisher p = (Publisher) o;
			System.out.println("i want to read magazine. " + p.getMagazineName());
		}
	}
}

3.测试类

package observer;
public class Main {
	public static void main(String[] args) {
		// create observer
		Reader reader=new Reader();
		// create observable
		Publisher publisher = new Publisher();
		// add observer
		publisher.addObserver(reader);
		// observable do some action
		publisher.publish("I am antlove.");
	}
}

评论

3 楼 antlove 2013-02-08  

zjuttsw 写道

Observer貌似是接口吧。。

是的。java.util.Observer,java.util.Observable应该表述为jdk的观察模式的通用实现。这个比较好，我之前的用词有点不恰当。

2 楼 zjuttsw 2013-02-06  

Observer貌似是接口吧。。

1 楼 lijiejava 2013-02-06