上一篇介绍了 监听器: 所谓的 观察者 并不是一直监听 而是通过通知方式 来传递行为,可能 对该模式理解不当 请指正
  下面总结了一下使用Obervable类和Oberser接口,还是看看源代码
package java.util;

// Referenced classes of package java.util:
//                        Observer, Vector

public class Observable {

  public Observable() {
    changed = false;
    obs = new Vector();
  }

  public synchronized void addObserver(Observer observer) {
    if (observer == null)
      throw new NullPointerException();
    if (!obs.contains(observer))
      obs.addElement(observer);
  }

  public synchronized void deleteObserver(Observer observer) {
    obs.removeElement(observer);
  }

  public void notifyObservers() {
    notifyObservers(null);
  }

  public void notifyObservers(Object obj)
        {
label0:
                {
                        synchronized(this)
                        {
                                if(changed)
                                        break label0;
                        }
                        return;
                }
                Object aobj[];
                aobj = obs.toArray();
                clearChanged();
                observable;
                JVM INSTR monitorexit ;
                    goto _L1
                exception;
                throw exception;
_L1:
                for(int i = aobj.length - 1; i >= 0; i--)
                        ((Observer)aobj[i]).update(this, obj);

                return;
        }

  public synchronized void deleteObservers() {
    obs.removeAllElements();
  }

  protected synchronized void setChanged() {
    changed = true;
  }

  protected synchronized void clearChanged() {
    changed = false;
  }

  public synchronized boolean hasChanged() {
    return changed;
  }

  public synchronized int countObservers() {
    return obs.size();
  }

  private boolean changed;
  private Vector obs;
}
接口Observer
public interface Observer {

  public abstract void update(Observable observable, Object obj);
}
和上一篇实现是一样的 方式
下面 看看使用,要模拟蚊子咬人 那么需要一个人,蚊子
人类:
/*
* 蚊子 要人的 监听器
*/
package MosquitoBiteMe2;

import java.util.Observable;
import java.util.Observer;

/*
* 四川师范大学 06级 刘毅
*/
public    class Person implements Observer {
  private String name;
        private byte count;
        public Person(String name) {
    super();
    this.name = name;
  }
  public void update(Observable o, Object arg) {
    /**
     * 判断是否是来自 蚊子的通知    
     * 判断通知的是否是我
     */
    if(Mosquito.class.isInstance(o)&&arg.hashCode()==this.hashCode()){
      /**
        * 将蚊子数加一
        */
      System.out.println(name+": 被蚊子咬了"+(++count)+"下...");
    }
    
  }

}

蚊子
package MosquitoBiteMe2;

import java.util.Observable;
import java.util.Observer;

/*
* 蚊子类
*/
@SuppressWarnings(value={"unchecked"})
public class Mosquito extends Observable{
    /**
     * 咬观察者 ob
     */    
    public void bite(Observer ob){
     this.setChanged();//设置状态被改变
     this.notifyObservers(ob);//通知观察者ob
    }
}
测试类:
package MosquitoBiteMe2;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class Test1 {
  public static void main(String args[]){
    // TODO Auto-generated method stub
                final Mosquito mos[] = new Mosquito[10]; //搞出10个蚊子来
                final Person ps[]=new Person[5];//搞出五个人出来
                for(int i=0;i<mos.length;i++) mos[i]=new Mosquito();
                ps[0]=new Person("刘毅");
                ps[1]=new Person("吴俊");
                ps[2]=new Person("骁勇");
                ps[3]=new Person("何况");
                ps[4]=new Person("萧萧");
                /**
                 * 添加观察者
                 */
                
                  for(int j=0;j<mos.length;j++){
                    for(int i=0;i<ps.length;i++){    
                            mos[j].addObserver(ps[i]);
                    }
                     }
                /**
                 * 启动 三个线程来模拟 蚊子咬人
                 */
                 ExecutorService exec = Executors.newFixedThreadPool(2);
                 exec.execute(new Runnable(){    
                    public void run(){
                     while(true){
                        try {
                 Thread.sleep(1000);
                                                        int m=new Random().nextInt(10);//蚊子
                                                        int p=new Random().nextInt(5);//人
                                                        mos[m].bite(ps[p]);
                                }catch(InterruptedException e) {
                         e.printStackTrace();
                    }
                     }
                    }
                 });
                exec.execute(new Runnable(){    
                  public void run(){
                    while(true){
                        try {
                 Thread.sleep(1000);
                                                     int m=new Random().nextInt(10);//蚊子
                                                     int p=new Random().nextInt(5);//人
                                                     mos[m].bite(ps[p]);
                                }catch(InterruptedException e) {
                         e.printStackTrace();
                    }
                    }
                 }
                 });
                 exec.execute(new Runnable(){    
                    public void run(){
                     while(true){
                        try {
                 Thread.sleep(1000);
                                                        int m=new Random().nextInt(10);//蚊子
                                                        int p=new Random().nextInt(5);//人
                                                        mos[m].bite(ps[p]);
                                }catch(InterruptedException e) {
                         e.printStackTrace();
                    }
                     }
                    }
                 });
                 //这里 额外添加了三个线程 但是每次 只有线程 在运行 呵呵 接触一下1.5的 线程并发库吧    
                 exec.shutdown(); //通知挂起的线程从线程池中移除
  }

}
运行结果:
萧萧: 被蚊子咬了1下...
吴俊: 被蚊子咬了1下...
何况: 被蚊子咬了2下...
何况: 被蚊子咬了1下...
萧萧: 被蚊子咬了2下...
何况: 被蚊子咬了3下...
吴俊: 被蚊子咬了2下...
萧萧: 被蚊子咬了3下...
骁勇: 被蚊子咬了1下...
吴俊: 被蚊子咬了3下...
萧萧: 被蚊子咬了4下...
吴俊: 被蚊子咬了4下...
何况: 被蚊子咬了4下...
萧萧: 被蚊子咬了5下...
吴俊: 被蚊子咬了5下...
骁勇: 被蚊子咬了2下...
骁勇: 被蚊子咬了3下...
萧萧: 被蚊子咬了6下...
何况: 被蚊子咬了5下...
骁勇: 被蚊子咬了4下...
萧萧: 被蚊子咬了7下...
骁勇: 被蚊子咬了5下...
刘毅: 被蚊子咬了1下...
萧萧: 被蚊子咬了8下...
何况: 被蚊子咬了6下...
刘毅: 被蚊子咬了2下...
何况: 被蚊子咬了7下...
萧萧: 被蚊子咬了9下...
何况: 被蚊子咬了8下...
萧萧: 被蚊子咬了10下...
刘毅: 被蚊子咬了3下...
刘毅: 被蚊子咬了3下...
刘毅: 被蚊子咬了4下...
何况: 被蚊子咬了9下...
萧萧: 被蚊子咬了11下...
萧萧: 被蚊子咬了12下...
吴俊: 被蚊子咬了6下...
刘毅: 被蚊子咬了5下...
萧萧: 被蚊子咬了13下...
骁勇: 被蚊子咬了6下...
刘毅: 被蚊子咬了6下...
吴俊: 被蚊子咬了7下...
刘毅: 被蚊子咬了7下...
萧萧: 被蚊子咬了14下...
骁勇: 被蚊子咬了7下...
萧萧: 被蚊子咬了15下...
我先前还很幸运: 没有怎么被咬 后来就惨了 还是给咬成了青红头了