Java-马士兵设计模式学习笔记-观察者模式-OOD 封装Listener

 一、概述

childe类中的是关联监听者dad的，若要再增加监听者，会很不方便，且要修改代码。好的方法是封装监听者类，用addListener()方法动态添加监听者

二、代码

1.Test.java

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class WakenUpEvent{           private long time;     private String location;     private Child source;           public WakenUpEvent(long time, String location, Child source) {         super();         this.time = time;         this.location = location;         this.source = source;     }       public long getTime() {         return time;     }       public void setTime(long time) {         this.time = time;     }       public String getLocation() {         return location;     }       public void setLocation(String location) {         this.location = location;     }       public Child getSource() {         return source;     }       public void setSource(Child source) {         this.source = source;     }             }   class Child implements Runnable {           private List<WakenUpListener> wakenUpListeners = new ArrayList<WakenUpListener>();           public void addWakenUpListener(WakenUpListener wul){         wakenUpListeners.add(wul);     }     public void wakeUp(){         for(int i = 0; i < wakenUpListeners.size(); i++){             WakenUpListener l = wakenUpListeners.get(i);             l.actionToWakenUp(new WakenUpEvent(System.currentTimeMillis(), "bed", this));         }     }       @Override     public void run() {         try {             Thread.sleep(3000);         } catch (Exception e) {             e.printStackTrace();         }         wakeUp();     } }     interface WakenUpListener {     public void actionToWakenUp(WakenUpEvent e); }   class Dad implements WakenUpListener {       public void actionToWakenUp(WakenUpEvent e) {         System.out.println("Fedd the child");     }       }   class GrandFather implements WakenUpListener {       public void actionToWakenUp(WakenUpEvent e) {         System.out.println("抱孩子");     }       }     public class Test {       public static void main(String[] args) {         Child c = new Child();         c.addWakenUpListener(new Dad());         c.addWakenUpListener(new GrandFather());         new Thread(c).start();     } }

　　

三、运行结果