适配器模式

 

将某个类的接口转换成与另一个接口兼容。适配器通过将原始接口进行转换，给用户提供一个兼容接口，使得原来因为接口不同而无法一起使用的类可以得到兼容。

适配器的存在，就是为了将已存在的东西（接口）转换成适合我们需要、能被我们所利用的东西。
在现实生活中，适配器更多的是作为一个中间层来实现这种转换作用。比如电源适配器，它是用于电流变换（整流）的设备。

 

 

  1 <?php
  2 /**
  3  * 本实例用于  将电子书  转换为  纸质书使用
  4  */
  5 
  6 interface PaperBookInterface
  7 {
  8     public function open();
  9     public function turnPage();
 10     public function getPage();
 11 }
 12 
 13 interface EBookInterface
 14 {
 15     public function unlock();
 16     public function pressNext();
 17 
 18     /**
 19      * returns current page and total number of pages, like [10, 100] is page 10 of 100
 20      * @return int[]
 21      */
 22     public function getPage();
 23 }
 24 
 25 
 26 /**
 27  * This is the adapter here. Notice it implements BookInterface,
 28  * therefore you don't have to change the code of the client which is using a PaperBook
 29  */
 30 class EBookToPaperBookAdapter implements PaperBookInterface
 31 {
 32     private $_eBook;
 33 
 34     public function __construct(\EBookInterface $eBook)
 35     {
 36         $this->_eBook = $eBook;
 37     }
 38 
 39     /**
 40      * This class makes the proper translation from one interface to another.
 41      */
 42     public function open()
 43     {
 44         $this->_eBook->unlock();
 45     }
 46 
 47     public function turnPage()
 48     {
 49         $this->_eBook->pressNext();
 50     }
 51 
 52     /**
 53      * notice the adapted behavior here: EBookInterface::getPage() will return two integers, but BookInterface
 54      * supports only a current page getter, so we adapt the behavior here
 55      *
 56      * @return int
 57      */
 58     public function getPage()
 59     {
 60         return $this->_eBook->getPage()[0];
 61     }
 62 }
 63 
 64 
 65 
 66 
 67 
 68 
 69 class Book implements PaperBookInterface
 70 {
 71     /**
 72      * @var int
 73      */
 74     private $page;
 75 
 76     public function open()
 77     {
 78         $this->page = 1;
 79     }
 80 
 81     public function turnPage()
 82     {
 83         $this->page++;
 84     }
 85 
 86     public function getPage(): int
 87     {
 88         return $this->page;
 89     }
 90 }
 91 
 92 
 93 class Kindle implements EBookInterface
 94 {
 95     /**
 96      * @var int
 97      */
 98     private $page = 1;
 99 
100     /**
101      * @var int
102      */
103     private $totalPages = 100;
104 
105     public function pressNext()
106     {
107         $this->page++;
108     }
109 
110     public function unlock()
111     {
112     }
113 
114     /**
115      * returns current page and total number of pages, like [10, 100] is page 10 of 100
116      *
117      * @return int[]
118      */
119     public function getPage()
120     {
121         return [$this->page, $this->totalPages];
122     }
123 }
124 
125 
126 
127 
128 
129 $kindle = new Kindle();
130 $book = new EBookAdapter($kindle);
131 
132 $book->open();
133 $book->turnPage();
View Code

 

posted @ 2017-01-09 00:15  _logan  阅读(118)  评论(0)  编辑  收藏  举报