/**
   * Use HTTP GET to ping an url
   *
   * /!\ Warning,the return value is always true,you must use === to test the response tyPE too.
   * 
   * @param string $url
   * @return boolean true or the error message
   */
  public static function pingDistantFile($url)
  {
    $options = array(
      CURLOPT_FOLLOWLOCATION => true,CURLOPT_URL => $url,CURLOPT_FaiLONERROR => true,// HTTP code > 400 will throw curl error
    );

    $ch = curl_init();
    curl_setopt_array($ch,$options);
    $return = curl_exec($ch);

    if ($return === false)
    {
      return curl_error($ch);
    }
    else
    {
      return true;
    }
  }

你也可以使用HEAD方法,但也许你的CDN被禁用了.