/**
  * 生成签名结果
  * @param $para_sort 已排序要签名的数组
  * return 签名结果字符串
  */
 function buildRequestMysign($para_sort)
 {
     //把数组所有元素,按照“参数=参数值”的模式用“&”字符拼接成字符串
     $prestr = \Library\pay\direct_pay\lib\AlipayCore::createLinkstring($para_sort);
     $mysign = "";
     switch (strtoupper(trim($this->alipay_config['sign_type']))) {
         case "MD5":
             $mysign = \Library\pay\direct_pay\lib\AlipayMd5::md5Sign($prestr, $this->alipay_config['key']);
             break;
         case "RSA":
             $mysign = AlipayRsa::rsaSign($prestr, $this->alipay_config['private_key_path']);
             break;
         case "0001":
             $mysign = AlipayRsa::rsaSign($prestr, $this->alipay_config['private_key_path']);
             break;
         default:
             $mysign = "";
     }
     return $mysign;
 }