php设计模式之单例模式代码

发布时间：2020-05-23 13:30:24 所属栏目：PHP 来源：互联网

导读：这篇文章主要为大家详细介绍了php设计模式之单例模式的实现代码，具有一定的参考价值，感兴趣的朋友可以参考一下

php设计模式之单例模式的例子，供大家参考，具体内容如下

//protected getter for singleton instances
protected static function getSingleton($className){
  //保证单例模式 并且不能从控制器实例化和克隆
  if (!isset(self::$instanceMap[$className])) {
    $object = new $className;
    //Make sure this object inherit from Singleton
    if ($object instanceof Fruit) {
      self::$instanceMap[$className] = $object;
      var_dump($object);
    } else {
      throw SingletonException("Class '$className' do not inherit from Singleton!");
    }
  }
  return self::$instanceMap[$className];
}

//protected constructor to prevent outside instantiation
protected function __construct(){}

//denie cloning of singleton objects
public final function __clone(){
  trigger_error('It is impossible to clone singleton',E_USER_ERROR);
}

}

class Apple extends Fruit{
protected $rndId;

public function __construct(){
  $this->rndId = rand();
}

public function whatAmI(){
  echo 'I am a Apple(' . $this->rndId . ')<br />';
}

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

以上就是本文的全部内容，希望对大家学习php程序设计有所帮助。

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