code: private static function requestIp()
      {
          if (isset($_SERVER['HTTP_REMOTEIP'])) {
              return $_SERVER['HTTP_REMOTEIP'];
          }
          if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
              return explode(',', $_SERVER['HTTP_X_FORWARDED_FOR'])[0];
          }
          if (isset($_SERVER['HTTP_X_REAL_IP'])) {
              return $_SERVER['HTTP_X_REAL_IP'];
          }
          return isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : '';
      }
docs: 获取访问的用户IP
  @return string