public class ResultNotify:Notify
    {
        public ResultNotify(Page page):base(page)
        {
        }

        public override void ProcessNotify()
        {
            WxPayData notifyData = GetNotifyData();

            //检查支付结果中transaction_id是否存在
            if (!notifyData.IsSet("transaction_id"))
            {
                //若transaction_id不存在，则立即返回结果给微信支付后台
                WxPayData res = new WxPayData();
                res.SetValue("return_code", "FAIL");
                res.SetValue("return_msg", "支付结果中微信订单号不存在");
                Log.Error(this.GetType().ToString(), "The Pay result is error : " + res.ToXml());
                page.Response.Write(res.ToXml());
                page.Response.End();
            }

            string transaction_id = notifyData.GetValue("transaction_id").ToString();

            //查询订单，判断订单真实性
            if (!QueryOrder(transaction_id))
            {
                //若订单查询失败，则立即返回结果给微信支付后台
                WxPayData res = new WxPayData();
                res.SetValue("return_code", "FAIL");
                res.SetValue("return_msg", "订单查询失败");
                Log.Error(this.GetType().ToString(), "Order query failure : " + res.ToXml());
                page.Response.Write(res.ToXml());
                page.Response.End();
            }
            //查询订单成功
            else
            {
                WxPayData res = new WxPayData();
                res.SetValue("return_code", "SUCCESS");
                res.SetValue("return_msg", "OK");
                Log.Info(this.GetType().ToString(), "order query success : " + res.ToXml());
                page.Response.Write(res.ToXml());
                page.Response.End();
            }
        }

        //查询订单
        private bool QueryOrder(string transaction_id)
        {
            WxPayData req = new WxPayData();
            req.SetValue("transaction_id", transaction_id);
            WxPayData res = WxPayApi.OrderQuery(req);
            if (res.GetValue("return_code").ToString() == "SUCCESS" &&
                res.GetValue("result_code").ToString() == "SUCCESS")
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }

public class Notify
    {
        public Page page {get;set;}
        public Notify(Page page)
        {
            this.page = page;
        }

        /// <summary>
        /// 接收从微信支付后台发送过来的数据并验证签名
        /// </summary>
        /// <returns>微信支付后台返回的数据</returns>
        public WxPayData GetNotifyData()
        {
            //接收从微信后台POST过来的数据
            System.IO.Stream s = page.Request.InputStream;
            int count = 0;
            byte[] buffer = new byte[1024];
            StringBuilder builder = new StringBuilder();
            while ((count = s.Read(buffer, 0, 1024)) > 0)
            {
                builder.Append(Encoding.UTF8.GetString(buffer, 0, count));
            }
            s.Flush();
            s.Close();
            s.Dispose();

            Log.Info(this.GetType().ToString(), "Receive data from WeChat : " + builder.ToString());

            //转换数据格式并验证签名
            WxPayData data = new WxPayData();
            try
            {
                data.FromXml(builder.ToString());
            }
            catch(WxPayException ex)
            {
                //若签名错误，则立即返回结果给微信支付后台
                WxPayData res = new WxPayData();
                res.SetValue("return_code", "FAIL");
                res.SetValue("return_msg", ex.Message);
                Log.Error(this.GetType().ToString(), "Sign check error : " + res.ToXml());
                page.Response.Write(res.ToXml());
                page.Response.End();
            }

            Log.Info(this.GetType().ToString(), "Check sign success");
            return data;
        }

        //派生类需要重写这个方法，进行不同的回调处理
        public virtual void ProcessNotify()
        {

        }
    }