package lnurd.test; 

import java.lang.reflect.Method; 
import java.util.Date; 

public class Event { 
 //要执行方法的对象 
 private Object object; 
 //要执行的方法名称 
 private String methodName; 
 //要执行方法的参数 
 private Object[] params; 
 //要执行方法的参数类型 
 private Class[] paramTypes; 

 public Event(){ 

 } 
 public Event(Object object,String methodName,Object...args){ 
  this.object=object; 
  this.methodName=methodName; 
  this.params=args; 
  contractParamTypes(this.params); 
 } 
 //根据参数数组生成参数类型数组 
 private void contractParamTypes(Object[] params){ 
  this.paramTypes=new Class[params.length]; 
  for(int i=0;i<params.length;i++){ 
   this.paramTypes[i]=params[i].getClass(); 
  } 
 } 

 public Object getObject() { 
  return object; 
 } 
      //若干setter getter省略 
 public void setParamTypes(Class[] paramTypes) { 
  this.paramTypes = paramTypes; 
 } 
 //执行该 对象的该方法 
 public void invoke() throws Exception{ 
  Method method=object.getClass().getMethod(this.getMethodName(), this.getParamTypes()); 
  if(null==method){ 
   return; 
  } 
  method.invoke(this.getObject(), this.getParams()); 
 } 
} 

package lnurd.test; 

import java.util.ArrayList; 
import java.util.List; 

public class EventHandler { 
 //是用一个List 
 private List<Event> objects; 

 public EventHandler(){ 
  objects=new ArrayList<Event>(); 
 } 
 //添加某个对象要执行的事件，及需要的参数 
 public void addEvent(Object object,String methodName,Object...args){ 
  objects.add(new Event(object,methodName,args)); 
 } 
 //通知所有的对象执行指定的事件 
 public void notifyX() throws Exception{ 
  for(Event e : objects){ 
   e.invoke(); 
  } 
 } 
} 

package lnurd.test; 

public abstract class Notifier { 
 private EventHandler eventHandler=new EventHandler(); 

 public EventHandler getEventHandler() { 
  return eventHandler; 
 } 
 public void setEventHandler(EventHandler eventHandler) { 
  this.eventHandler = eventHandler; 
 } 
 //增加需要帮忙放哨的学生 
 public abstract void addListener(Object object,String methodName,Object...args); 
 //告诉所有要帮忙放哨的学生：老师来了 
 public abstract void notifyX(); 
} 

package lnurd.test; 

public class GoodNotifier extends Notifier { 

 @Override 
 public void addListener(Object object, String methodName, Object... args) { 
  System.out.println("有新的同学委托尽职尽责的放哨人!"); 
  this.getEventHandler().addEvent(object, methodName, args); 
 } 

 @Override 
 public void notifyX() { 
  System.out.println("尽职尽责的放哨人告诉所有需要帮忙的同学：老师来了"); 
  try{ 
   this.getEventHandler().notifyX(); 
  }catch(Exception e){ 
   e.printStackTrace(); 
  } 
 } 

} 

//对于BadNotifier代码类似，不再复述. 

package lnurd.test; 

import java.util.Date; 

public class PlayingGameListener { 
 public PlayingGameListener(){ 
  System.out.println("我正在玩游戏 开始时间"+new Date()); 
 } 
 public void stopPlayingGame(Date date){ 
  System.out.println("老师来了，快回到座位上，结束时间"+date); 
 } 
} 

package lnurd.test; 

import java.util.Date; 

public class WatchingTVListener { 
 public WatchingTVListener(){ 
  System.out.println("我正在看电视 "+new Date()); 
 } 
 public void stopWatchingTV(Date date){ 
  System.out.println("老师来了，快关闭电视 。 结束时间"+date); 
 } 
} 

//创建一个尽职尽责的放哨者 
Notifier goodNotifier=new GoodNotifier(); 

//创建一个玩游戏的同学，开始玩游戏 
PlayingGameListener playingGameListener=new PlayingGameListener(); 
//创建一个看电视的同学，开始看电视 
WatchingTVListener watchingTVListener=new WatchingTVListener(); 
//玩游戏的同学告诉放哨的同学，老师来了告诉一下 
goodNotifier.addListener(playingGameListener, "stopPlayingGame",new Date()); 
//看电视的同学告诉放哨的同学，老师来了告诉一下 
goodNotifier.addListener(watchingTVListener, "stopWatchingTV",new Date()); 
try{ 
 //一点时间后 
 Thread.sleep(1000); 
}catch(Exception e){ 
 e.printStackTrace(); 
} 
//老师出现，放哨的人通知所有要帮忙的同学:老师来了 
goodNotifier.notifyX();