/**
  * @return RegistryCookie
  */
 public static function getInstance()
 {
     if (is_null(self::$_instance)) {
         self::$_instance = new RegistryCookie();
     }
     return self::$_instance;
 }
 /**
  * 删除cookie值 
  * @param $key
  */
 public static function delC($key)
 {
     RegistryCookie::getInstance()->del($key);
 }