它现在这种支付方式比较多象网银在线等使用的方法都是url验证，就是通过url参数和一个这些url参数的md5编码来确认这个连接的正确性，支付宝在你购买成功后跳转自定义连接的时候会传2次过来，第一次是数据底层请求，第二次是web请求，而只有第一次有验证码，这个只能通过记录下来才看的到，因为两次请求间隔很小，如果光显示的话最后的结果是被第二次覆盖了的。所以在接收的时候就要设定接收条件，一种是没有notify_type参数的，一种是有的。
我们先来看一下创建一个连接地址
t1=ConfigurationSettings.AppSettings["interface"];//支付接口，就是给的一个连接地址
t2=ConfigurationSettings.AppSettings["account"];//支付宝帐户你的帐户
t3=ConfigurationSettings.AppSettings["password"];//安全校验码，设置的商家验证码
t4="images/logo_zfbsmall.gif";//按钮图片地址
t5="test";//悬停说明
cmd="0001";//默认
subject="item";//商品名称
body="decrip";//描述
order_no=;//定单号，用户自己生成，方便自己管理 prices=100;//价格0.01～50000.00
rurl="http://www.xxx.com/";//商品展示网址
types="1";//1：商品购买2：服务购买3：网络拍卖4：捐赠
number="1";//购买数量
transport="3";//1：平邮2：快递3：虚拟物品
ordinary_fee="";//平邮运费
express_fee="";//快递运费
readonlys="true";//交易信息是否只读
buyer_msg="";//买家给卖家的留言
buyer="";//买家Email
buyer_name="";//买家姓名
buyer_address="";//买家地址
buyer_zipcode="";//买家邮编
buyer_tel="";//买家电话号码
buyer_mobile="";//买家手机号码
partner=ConfigurationSettings.AppSettings["partenid"];//合作伙伴ID，这个是固定的
上面就是要提供得基本信息，然后就是生成支付宝得连接，也就是给支付宝提供一条带验证的购买信息。
public string creatAlipayItemURL(string t1，string t2，string t3，string t4，string t5，string cmd，string subject，string body，string order_no，string prices，string rurl，string types，string number，string transport，string ordinary_fee，string express_fee，string readonlys，string buyer_msg，string buyer，string buyer_name，string buyer_address，string buyer_zipcode，string buyer_tel，string buyer_mobile，string partner)
{
string itemURL，str2CreateAc，acCode;
string INTERFACE_URL，sellerEmail，keyCode，imgsrc，imgtitle，AlipayItemURL;
//初始化各必要变量
INTERFACE_URL=t1+t2;//支付接口
sellerEmail=t2;//商户支付宝账户(改成你自己的)
keyCode=t3;//安全校验码(改成你自己的)
imgsrc=t4;//支付宝按钮图片
imgtitle=t5;//按钮悬停说明
str2CreateAc="cmd" + cmd + "subject" + subject;
str2CreateAc=str2CreateAc + "body" + body;
str2CreateAc=str2CreateAc + "order_no" + order_no;
str2CreateAc=str2CreateAc + "price" + prices;
//str2CreateAc=str2CreateAc + "url" + rurl;
str2CreateAc=str2CreateAc + "type" + types;
str2CreateAc=str2CreateAc + "number" + number;
str2CreateAc=str2CreateAc + "transport" + transport;
/*str2CreateAc=str2CreateAc + "ordinary_fee" + ordinary_fee;
str2CreateAc=str2CreateAc + "express_fee" + express_fee;
str2CreateAc=str2CreateAc + "readonly" + readonlys;
str2CreateAc=str2CreateAc + "buyer_msg" + buyer_msg;*/
str2CreateAc=str2CreateAc + "seller" + sellerEmail;
/*str2CreateAc=str2CreateAc + "buyer" + buyer;
str2CreateAc=str2CreateAc + "buyer_name" + buyer_name;
str2CreateAc=str2CreateAc + "buyer_address" + buyer_address;
str2CreateAc=str2CreateAc + "buyer_zipcode" + buyer_zipcode;
str2CreateAc=str2CreateAc + "buyer_tel" + buyer_tel;
str2CreateAc=str2CreateAc + "buyer_mobile" + buyer_mobile;*/
str2CreateAc=str2CreateAc + "partner" + partner;
str2CreateAc=str2CreateAc + keyCode;
//acCode=FormsAuthentication.HashPasswordForStoringInConfigFile(str2CreateAc，"MD5");
acCode=this.GetMD5(str2CreateAc，"gb2312");
itemURL=INTERFACE_URL + "？cmd=" + cmd;
itemURL=itemURL + "&subject=" + HttpUtility.UrlEncode(subject);
itemURL=itemURL + "&body=" + HttpUtility.UrlEncode(body);
itemURL=itemURL + "&order_no=" + order_no;
itemURL=itemURL + "&price=" + prices;
//itemURL=itemURL + "&url=" + rurl;
itemURL=itemURL + "&type=" + types;
itemURL=itemURL + "&number=" + number;
itemURL=itemURL + "&transport=" + transport;
/*itemURL=itemURL + "&ordinary_fee=" + ordinary_fee;
itemURL=itemURL + "&express_fee=" + express_fee;
itemURL=itemURL + "&readonly=" + readonlys;
itemURL=itemURL + "&buyer_msg=" + HttpUtility.UrlEncode(buyer_msg);
itemURL=itemURL + "&buyer=" + HttpUtility.UrlEncode(buyer);
itemURL=itemURL + "&buyer_name=" + HttpUtility.UrlEncode(buyer_name);
itemURL=itemURL + "&buyer_address=" + HttpUtility.UrlEncode(buyer_address);
itemURL=itemURL + "&buyer_zipcode=" + buyer_zipcode;
itemURL=itemURL + "&buyer_tel=" + buyer_tel;
itemURL=itemURL + "&buyer_mobile=" + buyer_mobile;*/
itemURL=itemURL + "&partner=" + partner;
itemURL=itemURL + "&ac=" + acCode;
AlipayItemURL=itemURL;
return AlipayItemURL;
}
这个函数就是返回生成的地址，里面注释掉的看你自己需要可以添加进去，然后就是md5码的问题，现在用默认的md5生成程序对中文的支持只限于GB2312，而支付宝使用的是GBK，虽然两个编码的内容GBK兼容GB2312但是毕竟两个编码方式不同，所以会产生错误，如果用英文或者数字不会有问题。上面下载里面带的一个md5.asp的算法支持中文。
现在已经可以跳转到支付宝的页面了，而我们这边就要自己记录用户的信息已经生成的定单编号，这样在支付宝返回信息的时候来查询。在设定了返回地址后，我们就要看接收页面了。
string msg_id，order_no，gross，buyer_email，buyer_name，buyer_address，buyer_zipcode，buyer_tel，buyer_mobile，action，s_date，ac，notify_type;
string returnTxt;//返回给支付宝通知接口的结果
string alipayNotifyURL;//支付宝查询接口URL
string myalipayEmail;//商户的支付宝Email
string ResponseTxt="";
returnTxt = "N";
alipayNotifyURL = ConfigurationSettings.AppSettings["interfaceback"];//支付宝查询接口地址
myalipayEmail = ConfigurationSettings.AppSettings["account"];//填写您的支付宝帐号
//检查支付宝通知接口传递过来的参数是否合法
msg_id = newop.DelStr(Request["msg_id"]);
order_no = newop.DelStr(Request["order_no"]);
gross = newop.DelStr(Request["gross"]);
buyer_email = newop.DelStr(Request["buyer_email"]);
buyer_name = newop.DelStr(Request["buyer_name"]);
buyer_address = newop.DelStr(Request["buyer_address"]);
buyer_zipcode = newop.DelStr(Request["buyer_zipcode"]);
buyer_tel = newop.DelStr(Request["buyer_tel"]);
buyer_mobile = newop.DelStr(Request["buyer_mobile"]);
action = newop.DelStr(Request["action"]);
s_date = newop.DelStr(Request["date"]);
ac = newop.DelStr(Request["ac"]);
notify_type = newop.DelStr(Request["notify_type"]);
alipayNotifyURL = alipayNotifyURL + "msg_id=" + msg_id + "&email=" + myalipayEmail + "&order_no=" + order_no;
System.Net.WebClient isClient= new System.Net.WebClient();
Stream isStream = isClient.OpenRead(alipayNotifyURL);
StreamReader isReader = new StreamReader(isStream，System.Text.Encoding.GetEncoding("GB2312"));
ResponseTxt = isReader.ReadToEnd();
if(action == "test")//测试商户网站URL是否正确安装
{
returnTxt = "Y";
}
else if((action=="sendOff")&&(msg_id！=""))//发货通知
{
returnTxt = "N";
if((ResponseTxt == "true")||(ResponseTxt == "false"))
{
//更新数据在商户系统里的订单数据;如果已经发货，则将returnTxt置为Y，否则为N
}
else
{
//非法数据，不做更新
returnTxt="Error";
}
}
else if((action=="sendOff")&&(notify_type=="web"))
{
//检查是否已经付帐，并记录 }
else if((action=="checkOut")&&(msg_id！=""))//交易结束通知
{
returnTxt = "Y";
if((ResponseTxt=="true")||(ResponseTxt == "false"))
{
//更新数据在商户系统里的订单数据;如果数据更新成功，则将returnTxt置为Y，否则为N
//更新数据
//你的代码，更新你这边数据
returnTxt= "Y";
}
else
{
//非法数据，不做更新
returnTxt = "Error";
}
}
else
{
returnTxt="Error";
}
Response.Write(returnTxt);