/**
  * 生成二维码后返回内容
  * @param $value
  * @return array
  */
 private function _getQrCodeContent($value)
 {
     apf_require_file('phpqrcode.php', 'classes/util/phpqrcode');
     $errorCorrectionLevel = "M";
     $matrixPointSize = "5";
     $image = QRcode::getImage($value, false, $errorCorrectionLevel, $matrixPointSize, 2);
     ob_start();
     ImagePNG($image);
     $content = ob_get_contents();
     ImageDestroy($image);
     ob_end_clean();
     return $content;
 }