php设计模式之单例模式代码

xgnic

            php设计模式之单例模式的例子，供大家参考，具体内容如下
rndId = rand();
    }
    public function whatAmI(){
      echo 'I am a Apple(' . $this->rndId . ')
';
    }
    public static function getInstance(){
      //echo get_class();
      return Fruit::getSingleton(get_class());
    }
  }
  class GreenApple extends Apple{
    public function whatAmI(){
      echo 'I am a GreenApple(' . $this->rndId . ')
';
    }
    public static function getInstance(){
      return Fruit::getSingleton(get_class());
    }
  }
  $apple1 = Apple::getInstance();
  //var_dump($apple1);
  $apple2 = GreenApple::getInstance();
  $apple1->whatAmI();// should echo 'I am a Apple(some number)
  $apple2->whatAmI();// should echo 'I am a GreenApple(some number)
  $apple1 = Apple::getInstance();
  $apple2 = GreenApple::getInstance();
  //保证单例模式
  $apple1->whatAmI();// should echo 'I am a Apple(same number as above)
  $apple2->whatAmI();// should echo 'I am a GreenApple(same number as above)
  // $a = clone $apple1;// this should fail
  // $b = clone $apple2;// this should fail