代理模式

 1 interface Subject {
 2     function Request();
 3 }
 4 class RealSubject implements Subject {
 5     public function Request() {
 6         echo '真实的请求';
 7     }
 8 }
 9 class Proxy implements Subject {
10     protected $subject = NULL;
11     public function Request() {
12         if (NULL === $this->subject) {
13             $this->subject = new RealSubject ();
14         }
15         $this->subject
16             ->Request ();
17     }
18 }
19 $proxy = new Proxy();
20 $proxy->Request();