转：http://blog.csdn.net/jxufewbt/archive/2007/08/04/1726168.aspx

复制C#代码保存代码
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;

public partial class pay : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Encoding gb2312 = Encoding.GetEncoding("gb2312");
        Response.ContentEncoding = gb2312;
        Request.ContentEncoding = gb2312;
    }

protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
    {
        if (Request.Cookies[FormsAuthentication.FormsCookieName] != null)
        {
            Vlike_DB_read a = new Vlike_DB_read();
            string zfb_ddh = a.get_zfb_id(Membership.GetUser().UserName, Convert.ToInt32(DropDownList1.SelectedValue));
            Response.Redirect(img("0001", "包月", "影视包月  10元/月", zfb_ddh, "10.00", Membership.GetUser().UserName.ToUpper(), DropDownList1.SelectedValue));
        }
        else
        {
            Response.Write("<script type='text/javascript'>alert('请先登陆!');</script>");
        }
    }

private string img(string strcmd, string strSub, string strSubinfo, string strid, string strMoney, string strUser, string strNum)
    {
        string strsellerEmail = "341081@qq.com";          //卖家支付宝帐号
        string strAc = "";        　　　　//卖家支付宝安全校验码
        string INTERFACE_URL = "https://www.alipay.com/payto:";
        string strCmd = strcmd;           //命令字
        string strSubject = strSub;       //商品名
        string strBody = strSubinfo;      //商品描述
        string strOrder_no = strid;       //商户订单号
        string strPrice = strMoney;       //商品单价 0.01～50000.00
        string rurl = "http://";          //商品展示网址
        string strType = "2";             //type支付类型    1：商品购买2：服务购买3：网络拍卖4：捐赠
        string strNumber = strNum;        //购买数量
        string strTransport = "3";        //发货方式        1：平邮2：快递3：虚拟物品
        string strOrdinary_fee = "";      //平邮运费
        string strExpress_fee = "";       //快递运费
        string strReadOnly = "true";      //交易信息是否只读
        string strBuyer_msg = "";         //买家给卖家的留言

string strBuyer = "";             //买家EMAIL
        string strBuyer_name = strUser;   //买家姓名
        string strBuyer_address = "";     //买家地址
        string strBuyer_zipcode = "";     //买家邮编
        string strBuyer_tel = "";         //买家电话号码
        string strBuyer_mobile = "";      //买家手机号码
        string strPartner = "";           //合作伙伴ID    保留字段

return CreatUrl(strsellerEmail, strAc, INTERFACE_URL, strCmd, strSubject, strBody,
            strOrder_no, strPrice, rurl, strType, strNumber, strTransport,
            strOrdinary_fee, strExpress_fee, strReadOnly, strBuyer_msg, strBuyer,
            strBuyer_name, strBuyer_address, strBuyer_zipcode, strBuyer_tel,
            strBuyer_mobile, strPartner);
    }
    private string CreatUrl(
        string strsellerEmail,
        string strAc,
        string INTERFACE_URL,
        string strCmd,
        string strSubject,
        string strBody,
        string strOrder_no,
        string strPrice,
        string rurl,
        string strType,
        string strNumber,
        string strTransport,
        string strOrdinary_fee,
        string strExpress_fee,
        string strReadOnly,
        string strBuyer_msg,
        string strBuyer,
        string strBuyer_name,
        string strBuyer_address,
        string strBuyer_zipcode,
        string strBuyer_tel,
        string strBuyer_mobile,
        string strPartner)
    {   //以下参数值不能留空

string str2CreateAc = "";
        str2CreateAc += "cmd" + strCmd + "subject" + strSubject;
        str2CreateAc += "body" + strBody;
        str2CreateAc += "order_no" + strOrder_no;
        str2CreateAc += "price" + strPrice;
        str2CreateAc += "url" + rurl;
        str2CreateAc += "type" + strType;
        str2CreateAc += "number" + strNumber;
        str2CreateAc += "transport" + strTransport;
        str2CreateAc += "ordinary_fee" + strOrdinary_fee;
        str2CreateAc += "express_fee" + strExpress_fee;
        str2CreateAc += "readonly" + strReadOnly;
        str2CreateAc += "buyer_msg" + strBuyer_msg;
        str2CreateAc += "seller" + strsellerEmail;
        str2CreateAc += "buyer" + strBuyer;
        str2CreateAc += "buyer_name" + strBuyer_name;
        str2CreateAc += "buyer_address" + strBuyer_address;
        str2CreateAc += "buyer_zipcode" + strBuyer_zipcode;
        str2CreateAc += "buyer_tel" + strBuyer_tel;
        str2CreateAc += "buyer_mobile" + strBuyer_mobile;
        str2CreateAc += "partner" + strPartner;
        str2CreateAc += strAc;

string acCode = GetMD5(str2CreateAc);

string parameter = "";

parameter += INTERFACE_URL + strsellerEmail + "?cmd=" + strCmd;
        parameter += "&subject=" + Server.UrlEncode(strSubject);
        parameter += "&body=" + Server.UrlEncode(strBody);
        parameter += "&order_no=" + strOrder_no;
        parameter += "&url=" + rurl;
        parameter += "&price=" + strPrice;
        parameter += "&type=" + strType;
        parameter += "&number=" + strNumber;
        parameter += "&transport=" + strTransport;
        parameter += "&ordinary_fee=" + strOrdinary_fee;
        parameter += "&express_fee=" + strExpress_fee;
        parameter += "&readonly=" + strReadOnly;
        parameter += "&buyer_msg=" + strBuyer_msg;
        parameter += "&buyer=" + strBuyer;
        parameter += "&buyer_name=" + Server.UrlEncode(strBuyer_name);
        parameter += "&buyer_address=" + strBuyer_address;
        parameter += "&buyer_zipcode=" + strBuyer_zipcode;
        parameter += "&buyer_tel=" + strBuyer_tel;
        parameter += "&buyer_mobile=" + strBuyer_mobile;
        parameter += "&partner=" + strPartner;
        parameter += "&ac=" + acCode;

return parameter;
    }

private static string GetMD5(string s)
    {
        System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
        byte[] t = md5.ComputeHash(System.Text.Encoding.GetEncoding("gb2312").GetBytes(s));
        System.Text.StringBuilder sb = new System.Text.StringBuilder(32);
        for (int i = 0; i < t.Length; i++)
        {
            sb.Append(t[i].ToString("x").PadLeft(2, '0'));
        }
        return sb.ToString();
    }
}
接收支付宝信息并进行相应操作

复制ASPX代码保存代码
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Web" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Net" %>
<%@ Import Namespace="System.Text" %>
<%@ Import Namespace="System.Security.Cryptography" %>

<script type="text/C#" runat="server">
private string returnTxt = "N";              //返回给支付宝通知接口的结果
private string alipayNotifyURL = "http://notify.alipay.com/trade/notify_query.do?";    //支付宝查询接口URL
private string myalipayEmail = "341081@qq.com";            //商户的支付宝Email
private string constPaySecurityCode = "";                  //码
private SqlConnection conn = new SqlConnection();

private string GetMD5(string s)
{
    System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
    byte[] t = md5.ComputeHash(System.Text.Encoding.GetEncoding("gb2312").GetBytes(s));
    StringBuilder sb = new StringBuilder(32);
    for (int i = 0; i < t.Length; i++)
    {
        sb.Append(t[i].ToString("x").PadLeft(2, '0'));
    }
    return sb.ToString();
}

private String Get_Http(String a_strUrl, int timeout)
{
    string strResult;
    try
    {
        System.Net.HttpWebRequest myReq = (System.Net.HttpWebRequest) System.Net.HttpWebRequest.Create(a_strUrl);
        myReq.Timeout = timeout;
        System.Net.HttpWebResponse HttpWResp = (System.Net.HttpWebResponse) myReq.GetResponse();
        Stream myStream = HttpWResp.GetResponseStream();
        StreamReader sr = new StreamReader(myStream, System.Text.Encoding.Default);
        System.Text.StringBuilder strBuilder = new System.Text.StringBuilder();
        while (-1 != sr.Peek())
        {
            strBuilder.Append(sr.ReadLine() + "\r\n");
        }
        strResult = strBuilder.ToString();
    }
    catch (Exception exp)
    {
        strResult = "错误：" + exp.Message;
    }
    return strResult;
}
public void send(string sql)
{
    string dbconn = "data source=127.0.0.1;UID=Cm;PWD=fallenangel;database=text";
    conn = new SqlConnection(dbconn);
    conn.Open();
    SqlCommand cmd = new SqlCommand(sql, conn);
    int aa = cmd.ExecuteNonQuery();
    conn.Close();
}

private void Page_Load(object sender, System.EventArgs e)
{
    //检查支付宝通知接口传递过来的参数是否合法
    string msg_id = System.Web.HttpContext.Current.Request["msg_id"];
    string order_no = System.Web.HttpContext.Current.Request["order_no"];
    string gross = System.Web.HttpContext.Current.Request["gross"];
    string buyer_email = System.Web.HttpContext.Current.Request["buyer_email"];
    string buyer_name = System.Web.HttpContext.Current.Request["buyer_name"];
    string buyer_address = System.Web.HttpContext.Current.Request["buyer_address"];
    string buyer_zipcode = System.Web.HttpContext.Current.Request["buyer_zipcode"];
    string buyer_tel = System.Web.HttpContext.Current.Request["buyer_tel"];
    string buyer_mobile = System.Web.HttpContext.Current.Request["buyer_mobile"];
    string action = System.Web.HttpContext.Current.Request["action"];
    string s_date = System.Web.HttpContext.Current.Request["date"];
    string ac = System.Web.HttpContext.Current.Request["ac"];
    string notify_type = System.Web.HttpContext.Current.Request["notify_type"];
    alipayNotifyURL = alipayNotifyURL + "msg_id=" + msg_id + "&email=" + myalipayEmail + "&order_no=" + order_no;

//获取支付宝ATN返回结果，true和false都是正确的订单信息，invalid 是无效的
    string responseTxt = Get_Http(alipayNotifyURL, 120000);
    string Str = "msg_id" + msg_id + "order_no" + order_no + "gross" + gross + "buyer_email" + buyer_email + "buyer_name" + buyer_name + "buyer_address" + buyer_address + "buyer_zipcode" + buyer_zipcode + "buyer_tel" + buyer_tel + "buyer_mobile" + buyer_mobile + "action" + action + "date" + s_date + constPaySecurityCode;

string ac_code = GetMD5(Str);

if (action == "test") //支付宝接口测试是否有效
    {
        returnTxt = "Y";
    }
    if (action == "sendOff")  //发货通知
    {
        if (responseTxt.Substring(0, 4) == "true"
            || responseTxt.Substring(0, 4) == "fals")//ATN，验证消息是否支付宝发过来
        {
            if (ac_code == ac)//验证消息是否被修改
            {
                //数据库操作
            }
        }
    }
    if (action == "checkOut")  //交易完成通知
    {
        returnTxt = "N";
        if (responseTxt.Substring(0, 4) == "true"
            || responseTxt.Substring(0, 4) == "fals")//ATN，验证消息是否支付宝发过来
        {
            if (ac_code == ac)//验证消息是否被修改
            {
                //数据库操作   
            }
        }
    }
    System.Web.HttpContext.Current.Response.Write(returnTxt);
}
</script>