[php]php设计模式 Observer(观察者模式)

<?php
  2 /**
  3  * 观察者模式
  4  * 
  5  * 定义对象间的一种一对多的依赖关系,以便当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并自动刷新
  6  * 能够便利地创建查看目标对象状态的对象,并且提供与核心对象非耦合的指定功能
  7  * 插件系统
  8 */
  9 class Observerable
 10 {
 11 private$_observers=array();
 12 
 13 publicfunction registerObserver($observer)
 14     {
 15 $this->_observers[] =$observer;
 16     }
 17 
 18 publicfunction removeObserver($observer)
 19     {
 20 $key=array_search($observer,$this->_observers);
 21 if(!($key===false))
 22         {
 23 unset($this->_observers[$key]);
 24         }
 25     }
 26 
 27 publicfunction notifyObservers()
 28     {
 29 foreach($this->_observers as$observer)
 30         {
 31 if($observer instanceof Observer) $observer->update($this);
 32         }
 33     }
 34 }
 35 
 36 interface Observer
 37 {
 38 publicfunction update($observer);
 39 }
 40 
 41 interface DisplayElement
 42 {
 43 publicfunction display();
 44 }
 45 
 46 // -- 实例类定义
 47 class NewsObserverable extends Observerable
 48 {
 49 private$_sports_news;
 50 publicfunction setSportsNews($data)
 51     {
 52 $this->_sports_news =$data;
 53 $this->notifyObservers();
 54     }
 55 
 56 publicfunction getSportsNews()
 57     {
 58 return$this->_sports_news;
 59     }
 60 
 61 private$_local_news;
 62 publicfunction setLocalNews($data)
 63     {
 64 $this->_local_news =$data;
 65 $this->notifyObservers();
 66     }
 67 
 68 publicfunction getLocalNews()
 69     {
 70 return$this->_local_news;
 71     }
 72 }
 73 
 74 class SportsNews implements Observer,DisplayElement
 75 {
 76 private$_data=null;
 77 publicfunction update($observer)
 78     {
 79 if($this->_data !=$observer->getSportsNews())
 80         {
 81 $this->_data =$observer->getSportsNews();
 82 $this->display();
 83         }
 84     }
 85 
 86 publicfunction display()
 87     {
 88 echo$this->_data.date("Y-m-d H:i:s")."<br/>";
 89     }
 90 }
 91 
 92 class LocalNews implements Observer,DisplayElement
 93 {
 94 private$_data=null;
 95 publicfunction update($observer)
 96     {
 97 if($this->_data !=$observer->getLocalNews())
 98         {
 99 $this->_data =$observer->getLocalNews();
100 $this->display();
101         }
102     }
103 
104 publicfunction display()
105     {
106 echo$this->_data.date("Y-m-d H:i:s")."<br/>";
107     }
108 }
109 
110 // -- 实例化 ---
111 
112 $objObserver=new NewsObserverable();
113 $local=new LocalNews();
114 $sports=new SportsNews();
115 
116 $objObserver->registerObserver($local);
117 $objObserver->registerObserver($sports);
118 
119 $objObserver->setSportsNews("sports news 1 ");
120 $objObserver->setLocalNews("local news 1 ");
121 $objObserver->removeObserver($sports);
122 $objObserver->setLocalNews("local news 2 ");
123 $objObserver->setSportsNews("sports news 2 ");
124 $objObserver->removeObserver($local);
125 $objObserver->setLocalNews("local news 3 ");