观察者设计模式例子

1.被观察对象

package 观察者设计模式;



import java.util.Observable;

//被观察者对象

public class ObserverObject extends Observable {

    public String toString()

    {

        return "张小二";

        

    }

    public void sentMessage(String s)

    {

        this.setChanged();

        this.notifyObservers(s);

    }

    

    



}

2.被观察对象

package 观察者设计模式;



import java.util.Observable;

import java.util.Observer;



public class Observer1  implements Observer{



    public void update(Observable arg0, Object arg1) {

        

        System.out.println("Observer1 receive " +arg1+" from "+arg0);

        

        

    }



}

package 观察者设计模式;



import java.util.Observable;

import java.util.Observer;



public class Observer2 implements Observer{



    public void update(Observable o, Object arg) {

        // TODO Auto-generated method stub

        System.out.println( "observer2 "+"received "+arg+"  from "+o);

        

    }



}

3.主类

 

package 观察者设计模式;



public class Main {



    public static void main(String[] args) {

        // TODO Auto-generated method stub

        ObserverObject obj=new ObserverObject();

        Observer1 osv=new Observer1();

        Observer2 osv2=new Observer2();

        obj.addObserver(osv);

        obj.addObserver(osv2);

        obj.sentMessage("hello");

        



    }



}