php设计模式之单例模式代码

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PHP设计模式之单例模式的例子,供大家参考,具体内容如下

PHP;"> //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。

原文链接:https://www.f2er.com/php/19566.html

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