1 class Dog
  2 {
  3     static $dx;
  4     public $test;
  5     
  6     private function __construct()
  7     {
  8         
  9     }
 10     
 11     static function DuiXiang()
 12     {
 13         //return new Dog();
 14         
 15         if(empty(self::$dx))
 16         {
 17             self::$dx = new Dog();
 18         }
 19         
 20         return self::$dx;
 21     }
 22 }
 23 
 24 $a = Dog::DuiXiang();
 25 
 26 
 27 $b = Dog::DuiXiang();
 28 $b->test="hello";
 29 
 30 
 31 var_dump($a);
 32 
 33 //工厂模式
 34 /*class YunSuan
 35 {
 36     public $a;
 37     public $b;
 38     
 39     function Jia()
 40     {
 41         return $a+$b;
 42     }
 43     function Jian()
 44     {
 45         return $a-$b;
 46     }
 47 }*/
 48 
 49 abstract class YuanSuan
 50 {
 51     public $a;
 52     public $b;
 53     
 54     function Suan()
 55     {
 56     }
 57 }
 58 
 59 class Jia extends YuanSuan
 60 {
 61     function Suan()
 62     {
 63         return $this->a+$this->b;
 64     }
 65 }
 66 
 67 class Jian extends YuanSuan
 68 {
 69     function Suan()
 70     {
 71         return $this->a-$this->b;
 72     }
 73 }
 74 
 75 class Cheng extends YuanSuan
 76 {
 77     function Suan()
 78     {
 79         return $this->a*$this->b;
 80     }
 81 }
 82 
 83 /*$j = new Cheng();
 84 $j->Suan();
 85 */
 86 
 87 class GongChang
 88 {
 89     static function ShengChan($f)
 90     {
 91         switch($f)
 92         {
 93             case "+":
 94                 return new Jia();
 95                 break;
 96             case "-":
 97                 return new Jian();
 98                 break;
 99             case "*":
100                 return new Cheng();
101                 break;
102         }
103     }
104 }
105 
106 
107 $r = GongChang::ShengChan("*");
108 $r->a=10;
109 $r->b=5;
110 echo $r->Suan();