php设计模式 Observer(观察者模式)

安哥网络

1. <?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")."
    
89. ";
    
90.     }
    
91. }
    
92. 
    
93. class LocalNews implements Observer,DisplayElement
    
94. {
    
95. private$_data=null;
    
96. publicfunction update($observer)
    
97.     {
    
98. if($this->_data !=$observer->getLocalNews())
    
99.         {
    
100. $this->_data =$observer->getLocalNews();
     
101. $this->display();
     
102.         }
     
103.     }
     
104. 
     
105. publicfunction display()
     
106.     {
     
107. echo$this->_data.date("Y-m-d H:i:s")."
     
108. ";
     
109.     }
     
110. }
     
111. 
     
112. // -- 实例化 ---
     
113. 
     
114. $objObserver=new NewsObserverable();
     
115. $local=new LocalNews();
     
116. $sports=new SportsNews();
     
117. 
     
118. $objObserver->registerObserver($local);
     
119. $objObserver->registerObserver($sports);
     
120. 
     
121. $objObserver->setSportsNews("sports news 1 ");
     
122. $objObserver->setLocalNews("local news 1 ");
     
123. $objObserver->removeObserver($sports);
     
124. $objObserver->setLocalNews("local news 2 ");
     
125. $objObserver->setSportsNews("sports news 2 ");
     
126. $objObserver->removeObserver($local);
     
127. $objObserver->setLocalNews("local news 3 ");

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本文摘自：http://www.cnblogs.com/bluefrog/archive/2011/06/14/2080208.html