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