string DecodeData()
        {
            string msg_signature = WebHelper.GetQueryString("msg_signature");
            string timestamp     = WebHelper.GetQueryString("timestamp");
            string nonce         = WebHelper.GetQueryString("nonce");
            string xmlData       = getXmlData(); //加密过的xml

            return(AIHelper.DecodeXml(msg_signature, timestamp, nonce, xmlData));
        }