[php]php设计模式 State (状态模式)

<?php
 2 /**
 3  * 状态模式
 4  *
 5  * 允许一个对象在其内部状态改变时改变它的行为,对象看起来似乎修改了它所属的类
 6  *
 7 */
 8 interface State
 9 {
10 publicfunction handle($state);
11 publicfunction display();
12 }
13 
14 class Context
15 {
16 private$_state=null;
17 
18 publicfunction __construct($state)
19     {
20 $this->setState($state);
21     }
22 
23 publicfunction setState($state)
24     {
25 $this->_state =$state;
26     }
27 
28 publicfunction request()
29     {
30 $this->_state->display();
31 $this->_state->handle($this);
32     }
33 }
34 
35 class StateA implements State
36 {
37 publicfunction handle($context)
38     {
39 $context->setState(new StateB());
40     }
41 
42 publicfunction display()
43     {
44 echo"state A<br/>";
45     }
46 }
47 
48 class StateB implements State
49 {
50 publicfunction handle($context)
51     {
52 $context->setState(new StateC());
53     }
54 
55 publicfunction display()
56     {
57 echo"state B<br/>";
58     }
59 }
60 
61 class StateC implements State
62 {
63 publicfunction handle($context)
64     {
65 $context->setState(new StateA());
66     }
67 
68 publicfunction display()
69     {
70 echo"state C<br/>";
71     }
72 }
73 
74 // 实例化一下
75 $objContext=new Context(new StateB());
76 $objContext->request();
77 $objContext->request();
78 $objContext->request();
79 $objContext->request();
80 $objContext->request();