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);

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