代理模式

 1 <?php
 2 
 3 /**
 4  * 和装饰器模式的区别：装饰器模式为了增强功能，而代理模式是为了加以控制
 5  *
 6  * 装饰器为对象添加一个或多个功能，而代理则控制对对象的访问
 7  */
 8 
 9 interface image
10 {
11     public function display();
12 }
13 
14 class RealImage implements image
15 {
16     private $_imgSrc;
17 
18     public function __construct($imgSrc)
19     {
20         $this->_imgSrc = $imgSrc;
21         $this->loadFromDisk();
22     }
23 
24     private function loadFromDisk()
25     {
26         echo "Load {$this->_imgSrc} from disk<br/>";
27     }
28 
29     public function display()
30     {
31         echo "Display {$this->_imgSrc}";
32     }
33 }
34 
35 
36 class ProxyImage implements image
37 {
38     private $_imgSrc;
39     private $_realImage;
40 
41     public function __construct($imgSrc)
42     {
43         $this->_imgSrc = $imgSrc;
44     }
45 
46     public function display()
47     {
48         if (!$this->_realImage instanceof RealImage) {
49             $this->_realImage = new RealImage($this->_imgSrc);
50         }
51 
52         $this->_realImage->display();
53     }
54 }
55 
56 
57 
58 $p = new ProxyImage(‘a.png‘);
59 $p->display();
60 
61 echo "<br/><br/>";
62 $p->display();