《大话设计模式》——读后感 （6）老板回来了，我不知道？——观察者模式之事件委托（2）

什么都不说，直接上代码，自己去理解，要结合动态代理看

Event：

package com.sjmx.observer.application;

import java.lang.reflect.Method;

public class Event { 

    private Object object;  

    private String methodName;  

    private Object[] params;  

    private Class[] paramTypes;  

    public Event(Object object,String method,Object...args)
    {
        this.object = object;
        this.methodName = method;
        this.params = args;
        contractParamTypes(this.params);
    }  

    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 void invoke() throws Exception
    {
        Method method = object.getClass().getMethod(this.methodName, this.paramTypes);//判断是否存在这个函数
        if (null == method)
        {
            return;
        }
        method.invoke(this.object, this.params);//利用反射机制调用函数
    }
}  

EventHandler ：

package com.sjmx.observer.application;

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

public class EventHandler {

    private List<Event> objects;  

    public EventHandler()
    {
        objects = new ArrayList<Event>();
    }  

    public void addEvent(Object object, String methodName, Object...args)
    {
        objects.add(new Event(object, methodName, args));
    }  

    public void notifyX() throws Exception
    {
        for (Event event : objects)
        {
            event.invoke();
        }
    }  

}

主题（通知）接口：

package com.sjmx.observer.application;

public abstract class Notifier {

      private EventHandler eventHandler = new EventHandler();  

        public EventHandler getEventHandler()
        {
            return eventHandler;
        }  

        public void setEventHandler(EventHandler eventHandler)
        {
            this.eventHandler = eventHandler;
        }  

        public abstract void addListener(Object object,String methodName, Object...args);  

        public abstract void notifyX();  

}

具体通知实体：

package com.sjmx.observer.application;

public class ConcreteNotifier extends Notifier {

    @Override
    public void addListener(Object object, String methodName, Object... args) {
          this.getEventHandler().addEvent(object, methodName, args);
    }

    @Override
    public void notifyX() {
        try {
            this.getEventHandler().notifyX();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

}

具体观察者：

1、不好好工作，在扯淡：

package com.sjmx.observer.application;

import java.util.Date;

public class TalkingListener {

    public TalkingListener()
    {
        System.out.println("working no,Talking");
    }

    public void stopTalking(Date date)
    {
        System.out.println("stop talking:" + date);
    }
}

2、上班期间看NBA

package com.sjmx.observer.application;

import java.util.Date;

public class WatchingNBAListener {

    public WatchingNBAListener()
    {
        System.out.println("watching NBA");
    }

    public void stopWatchingNBA(Date date)
    {
        System.out.println("stop watching:" + date);
    }
}

3、玩股票

package com.sjmx.observer.application;

import java.util.Date;

public class WatchingStockListener {

    public WatchingStockListener()
    {
        System.out.println("watchingStock");
    }

    public void stopWatchingStock(Date date)
    {
        System.out.println("stop watchingStock:" + date);
    }

}

客户端:

package com.sjmx.observer.application;

import java.util.Date;

public class Client {

      public static void main (String[] args)
        {
            Notifier goodNotifier = new ConcreteNotifier();  

            //看NBA
            WatchingNBAListener watchingNBAListener = new WatchingNBAListener();
            //看股票
            WatchingStockListener watchingStockListener = new WatchingStockListener();
            //不好好工作，在聊天
            TalkingListener talkingListener = new TalkingListener();

            goodNotifier.addListener(watchingNBAListener, "stopWatchingNBA", new Date());
            goodNotifier.addListener(watchingStockListener, "stopWatchingStock", new Date());
            goodNotifier.addListener(talkingListener, "stopTalking", new Date());

            goodNotifier.notifyX();
        }  

}

zookeeper的事件订阅模式，就是充分的发挥的观察者模式的作用，有兴趣的可以看看