public class ReturnHandler:System.Web.IHttpHandler

    {

        #region IHttpHandler 成员

        public bool IsReusable

        {

            get { return false; }

        }

        public String Get_Http(String a_strUrl, int timeout)

        {

            string strResult;

            try

            {

                HttpWebRequest myReq = (HttpWebRequest)HttpWebRequest.Create(a_strUrl);

                myReq.Timeout = timeout;

                HttpWebResponse HttpWResp = (HttpWebResponse)myReq.GetResponse();

                Stream myStream = HttpWResp.GetResponseStream();

                StreamReader sr = new StreamReader(myStream, Encoding.Default);

                StringBuilder strBuilder = new StringBuilder();

                while (-1 != sr.Peek())

                {

                    strBuilder.Append(sr.ReadLine());

                }

                strResult = strBuilder.ToString();

            }

            catch (Exception exp)

            {

                strResult = "错误：" + exp.Message;

            }

            return strResult;

        }

        public void ProcessRequest(System.Web.HttpContext context)

        {

            string requesturl = context.Server.UrlDecode(context.Request.Path);

            string alipayNotifyURL = Untity.Service_Ulr;

            string urltype=System.IO.Path.GetFileName(requesturl).Substring(0, 1).ToLower();

            MatchCollection matchs = Regex.Matches(requesturl, @"_([0-9a-zA-Z\%=]+)");

            string TypeName = System.Text.Encoding.ASCII.GetString(Convert.FromBase64String(matchs[0].Groups[1].Value));

            IReturnHandler handler = (IReturnHandler)Activator.CreateInstance(Type.GetType(TypeName));

            IList<string> paramsdata = new List<string>();

            for (int k = 1; k < matchs.Count; k++)

            {

                paramsdata.Add(matchs[k].Groups[1].Value);

            }

            string partner = handler.Partner;

            string key = handler.Key;

            NameValueCollection payResultData;

            if (urltype == "r")

            {

                payResultData = context.Request.QueryString;

            }

            else

            {

                payResultData = context.Request.Form;

            }

            alipayNotifyURL = alipayNotifyURL + "service=notify_verify" + "&partner=" + partner + "&notify_id=" + payResultData["notify_id"];

            string responseTxt = Get_Http(alipayNotifyURL, 120000);

            int i;

            String[] requestarr = payResultData.AllKeys;

            //进行排序；

            string[] Sortedstr = Untity.BubbleSort(requestarr);

            //构造待md5摘要字符串；

            string prestr = "";

            for (i = 0; i < Sortedstr.Length; i++)

            {

                if (context.Request.Form[Sortedstr[i]] != "" && Sortedstr[i] != "sign" && Sortedstr[i] != "sign_type")

                {

                    if (i == Sortedstr.Length - 1)

                    {

                        prestr = prestr + Sortedstr[i] + "=" + payResultData[Sortedstr[i]];

                    }

                    else

                    {

                        prestr = prestr + Sortedstr[i] + "=" + payResultData[Sortedstr[i]] + "&";

                    }

                }

            }

            prestr = prestr + key;

            string mysign =Untity.GetMD5(prestr);

            string sign = payResultData["sign"];

           if (responseTxt == "true" && mysign == sign)   //验证支付发过来的消息，签名是否正确

            {

                string status = payResultData["trade_status"];

                if (status == "TRADE_FINISHED")// WAIT_SELLER_SEND_GOODS  判断支付状态（文档中有枚举表可以参考）           

                {

                    //更新自己数据库的订单语句，请自己填写一下

                    if (urltype == "r")

                    {

                        handler.Return(payResultData, paramsdata);

                    }

                    else

                    {

                        handler.Notify(payResultData, paramsdata);

                    }

                }

            }

            else

            {

                handler.OnError(payResultData, paramsdata, responseTxt);

            }

        }

        #endregion

    }