对设计模式—Observer模式的认识

今天上班偷偷的把qq打开了，一会收到许多群里发的消息，这让我想到了Observer模式
。　Observer模式的功用，是希望两个（或多个）对象，我们称之为Subject和Observer，当一方的状态发生改变的时候，另一方能够得到通知。也就是说，作为Observer的一方，能够监视到Subject的某个特定的状态变化，并为之做出反应。
我对观察者理解就是一个中心点把所有变化的信息都收集上来，这个中心点有一个名单，根据名单把所有变化的信息散发出去。下面是对学生和老师发送的会议通知：

public interface Subject //
{
    public void register(Object object);
    public void remove(Object object);
    public void nofiyObserver();
    public void setMeeting(String meeting);
}

public class SubjectCenter implements Subject
{
    private List<Object> list = new ArrayList<Object>();
    private String meeting;
     
    public void register(Object object);
    {
         list.add(object);//survey name list 
    }

    public void remove(Object object);
    {
       if(list.indexOf(object) > 0) //remove name list
          list.remove(i);
    }

    public void nofiyObserver();
    {
       for(int i = 0;i < list.size();i++)
       {
            Observer observer =(Observer)list.get(i);
            //nofiy student and teacher join to meeting 
            observer.update(meeting);
       }
    }

    public void setMeeting(Sting meet)
    {
       this.meeting = meeting;//the school have a meeting;
       nofiyObserver();      // send  meeting message
    }
}

public interface Observer
{
   public void update(String info);
}

public class  Student implements Observer
{
   public void update(String info)
   {
      System.out.println("Hi Guys ,Today have a meeting about" +info);
   }
}

public class Teacher implements Observer
{
   public void update(String info)
   {
      System.out.println("Hi Sir,Today have a meeting about"+info);
   } 

}

public class TestObserver
{
   public static void main(String[]args)
   {
      Subject subject = new SubjectCenter();
      Oberver student = new Student();
      Oberver teacher = new Teacher();
      subject.register(student);//add student observer
      subject.register(teacher); //add teacher observer
      subject.setMeeting("Wrap-up meeting");
   }
}

评论

2 楼 flysnail 2008-11-29  

呵呵，失误。谢谢。

1 楼 langyu 2008-11-14  

setMeeting还是setInfo?remove方法里面的i从哪来的?
你那不报错吗？