事件处理模型:

组件(事件源)不处理自己的事件,而是将事件处理托付给外部的处理实体（监听器,

这样的事件处理模型称为事件的 授权处理模型。

不同的事件，能够交由不同类型的监听器去处理

事件源:

提供订阅与取消监听者的方法，并负责维护监听者列表，发送事件给监听者

监听者:

每一个监听者实现接口来接收事件,并负责从事件源订阅与取消订阅

图示:

demo

事件源:

Context:

package com.demo.event;import java.util.ArrayList;
import java.util.List;public class Context {private static List<Listener> list=new ArrayList<Listener>();public static void addListener(Listener listener){list.add(listener);}public static void removeListener(Listener listener){list.remove(listener);}public static void sendNotification(Event event){for(Listener listener:list){listener.onChange(event);}}
}

监听者:

Listener

package com.demo.event;public interface Listener {public void onChange(Event event);
}

MyListener

package com.demo.event;public class MyListener implements Listener {@Overridepublic void onChange(Event event) {switch(event.getType()){case Event.INSTALLED:System.out.println("do install...");break;case Event.STARTED :System.out.println("do started...");break;case Event.RESOLVED :System.out.println("do resolved...");break;case Event.STOPPED :System.out.println("do stopped...");break;case Event.UNRESOLVED :System.out.println("do unresolved...");break;case Event.UNINSTALLED :System.out.println("do uninstalled...");break;default:throw new IllegalArgumentException();}}}

事件:

package com.demo.event;public class Event {public static final int INSTALLED =1; public static final int STARTED =2; public static final int RESOLVED  =3; public static final int STOPPED =4; public static final int UNRESOLVED  =5; public static final int UNINSTALLED   =6;private int type ;private Object source ;public Event(int type, Object source) {this.type = type;this.source = source;}public int getType() {return type;}public Object getSource() {return source;}
}

測试:

package com.demo.event;public class EventTest {/*** @param args*/public static void main(String[] args) {Listener listener=new MyListener();//加入监听者Context.addListener(listener);//模拟bundle安装完毕事件触发Context.sendNotification(new Event(Event.INSTALLED, new MyBundle()));}}