/**
  * 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)
 {
     $prestr = llpayCore::createLinkstring($para_sort);
     $prestr = stripslashes($prestr);
     switch (strtoupper(trim($this->llpay_config['sign_type']))) {
         case "MD5":
             $mysign = llpayMd5::md5Sign($prestr, $this->llpay_config['key']);
             break;
         case "RSA":
             $mysign = llpayRsa::RsaSign($prestr, $this->llpay_config['RSA_PRIVATE_KEY']);
             break;
         default:
             $mysign = "";
     }
     return $mysign;
 }