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");
        

    }

}