C#微信开发之旅(九)：JSAPI支付(V3)

微信开发遇到最复杂的就是支付了，无论V2还是V3。这篇文章将给出全套的V3版本JSAPI支付代码，包括预支付->支付->订单查询->通知->退款，其中前三步已经上线应用，退款只是简单测试了一下，大家要用的话需要谨慎。。。

一、预支付&支付

实际就是讲订单信息交给微信端，返回给我们一个预支付id（与V2app支付相似），支付时将预支付id交给微信处理。注意：预支付id 需存储，每个out_trade_no（我们自己的订单号）只能对应一个预支付id。代码奉上：（mvc demo 最后会一并发出）

        public ActionResult Pay()
        {
            string code = "";//网页授权获得的code
            string orderNo = ""; //文档中的out_trade_no
            string description = ""; //商品描述
            string totalFee = "1";//订单金额（单位：分）
            string createIp = "127.0.0.1";
            string notifyUrl = ""; //通知url
            string openId = WeiXinHelper.GetUserOpenId(code);//通过网页授权code获取用户openid（或者之前有存储用户的openid 也可以直接拿来用）

            //prepayid 只有第一次支付时生成，如果需要再次支付，必须拿之前生成的prepayid。
            //也就是说一个orderNo 只能对应一个prepayid
            string prepayid = string.Empty;

            #region 之前生成过 prepayid，此处可略过

            //创建Model
            UnifiedWxPayModel model = UnifiedWxPayModel.CreateUnifiedModel(WeiXinConst.AppId, WeiXinConst.PartnerId, WeiXinConst.PartnerKey);

            //预支付
            UnifiedPrePayMessage result = WeiXinHelper.UnifiedPrePay(model.CreatePrePayPackage(description, orderNo, totalFee, createIp, notifyUrl, openId));

            if (result == null
                    || !result.ReturnSuccess
                    || !result.ResultSuccess
                    || string.IsNullOrEmpty(result.Prepay_Id))
            {
                throw new Exception("获取PrepayId 失败");
            }

            //预支付订单
            prepayid = result.Prepay_Id;

            #endregion
            
            //JSAPI 支付参数的Model
            PayModel payModel = new PayModel()
            {
                AppId = model.AppId,
                Package = string.Format("prepay_id={0}", prepayid),
                Timestamp = ((DateTime.Now.ToUniversalTime().Ticks - 621355968000000000) / 10000000).ToString(),
                Noncestr = CommonUtil.CreateNoncestr(),
            };

            Dictionary<string, string> nativeObj = new Dictionary<string, string>();
            nativeObj.Add("appId", payModel.AppId);
            nativeObj.Add("package", payModel.Package);
            nativeObj.Add("timeStamp", payModel.Timestamp);
            nativeObj.Add("nonceStr", payModel.Noncestr);
            nativeObj.Add("signType", payModel.SignType);
            payModel.PaySign = model.GetCftPackage(nativeObj); //生成JSAPI 支付签名


            return View(payModel);
        }

UnifiedWxPayModel 为V3统一支付帮助类，包括V3相关接口参数生成及签名的实现：

这里用到的 生成预支付请求参数Xml：

        #region 生成 预支付 请求参数（XML）
        /// <summary>
        /// 生成 预支付 请求参数（XML）
        /// </summary>
        /// <param name="description"></param>
        /// <param name="tradeNo"></param>
        /// <param name="totalFee"></param>
        /// <param name="createIp"></param>
        /// <param name="notifyUrl"></param>
        /// <param name="openid"></param>
        /// <returns></returns>
        public string CreatePrePayPackage(string description, string tradeNo, string totalFee, string createIp, string notifyUrl, string openid)
        {
            Dictionary<string, string> nativeObj = new Dictionary<string, string>();

            nativeObj.Add("appid", AppId);
            nativeObj.Add("mch_id", PartnerId);
            nativeObj.Add("nonce_str", CommonUtil.CreateNoncestr());
            nativeObj.Add("body", description);
            nativeObj.Add("out_trade_no", tradeNo);
            nativeObj.Add("total_fee", totalFee); //todo:写死为1
            nativeObj.Add("spbill_create_ip", createIp);
            nativeObj.Add("notify_url", notifyUrl);
            nativeObj.Add("trade_type", "JSAPI");
            nativeObj.Add("openid", openid);
            nativeObj.Add("sign", GetCftPackage(nativeObj));

            return DictionaryToXmlString(nativeObj);
        }

        #endregion

预支付请求在WeiXinHelper中，实现方式与前几篇中相似，这里就不上代码了。

二、订单查询

JSAPI返回支付成功，我们需要到后台查询下订单状态以确定支付是否成功，如果后台未接到通知，则要到微信服务器查询订单状态；最后才能展示给用户支付的结果：

        /// <summary>
        /// 到微信服务器查询 订单支付的结果 (jsapi支付返回ok，我们要判断下服务器支付状态，如果没有支付成功，到微信服务器查询）
        /// </summary>
        /// <param name="orderNo"></param>
        public bool QueryOrder(string orderNo)
        {
            //这里应先判断服务器 订单支付状态，如果接到通知，并已经支付成功，就不用 执行下面的查询了
            UnifiedWxPayModel model = UnifiedWxPayModel.CreateUnifiedModel(WeiXinConst.AppId, WeiXinConst.PartnerId, WeiXinConst.PartnerKey);
            UnifiedOrderQueryMessage message = WeiXinHelper.UnifiedOrderQuery(model.CreateOrderQueryXml(orderNo));
            //此处主动查询的结果，只做查询用（不能作为支付成功的依据）
            return message.Success;
        }

生成订单查询Xml方法：

        #region 创建订单查询 XML
        /// <summary>
        /// 创建订单查询 XML
        /// </summary>
        /// <param name="orderNo"></param>
        /// <returns></returns>
        public string CreateOrderQueryXml(string orderNo)
        {
            Dictionary<string, string> nativeObj = new Dictionary<string, string>();

            nativeObj.Add("appid", AppId);
            nativeObj.Add("mch_id", PartnerId);
            nativeObj.Add("out_trade_no", orderNo);
            nativeObj.Add("nonce_str", CommonUtil.CreateNoncestr());
            nativeObj.Add("sign", GetCftPackage(nativeObj));

            return DictionaryToXmlString(nativeObj);
        }
        #endregion

三、通知

微信支付通知以Post Xml方式：

        /// <summary>
        /// 微信支付通知（貌似比较臃肿，待优化）
        /// </summary>
        /// <returns></returns>
        public void Notify()
        {
            ReturnMessage returnMsg = new ReturnMessage() { Return_Code = "SUCCESS", Return_Msg = "" };
            string xmlString = GetXmlString(Request);
            NotifyMessage message = null;
            try
            {
                //此处应记录日志
                message = HttpClientHelper.XmlDeserialize<NotifyMessage>(xmlString);

                #region 验证签名并处理通知
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(xmlString);

                Dictionary<string, string> dic = new Dictionary<string, string>();
                string sign = string.Empty;
                foreach (XmlNode node in doc.FirstChild.ChildNodes)
                {
                    if (node.Name.ToLower() != "sign")
                        dic.Add(node.Name, node.InnerText);
                    else
                        sign = node.InnerText;
                }

                UnifiedWxPayModel model = UnifiedWxPayModel.CreateUnifiedModel(WeiXinConst.AppId, WeiXinConst.PartnerId, WeiXinConst.PartnerKey);
                if (model.ValidateMD5Signature(dic, sign))
                {
                    //处理通知
                }
                else
                {
                    throw new Exception("签名未通过！");
                }

                #endregion

            }
            catch (Exception ex)
            {
                //此处记录异常日志
                returnMsg.Return_Code = "FAIL";
                returnMsg.Return_Msg = ex.Message;
            }
            Response.Write(returnMsg.ToXmlString());
            Response.End();
        }

        /// <summary>
        /// 获取Post Xml数据
        /// </summary>
        /// <param name="request"></param>
        /// <returns></returns>
        private string GetXmlString(HttpRequestBase request)
        {
            using (System.IO.Stream stream = request.InputStream)
            {
                Byte[] postBytes = new Byte[stream.Length];
                stream.Read(postBytes, 0, (Int32)stream.Length);
                return System.Text.Encoding.UTF8.GetString(postBytes);
            }
        }

ReturnMessage是调用V3接口返回消息基类，也包含了给微信返回消息的方法：

    /// <summary>
    /// 消息基类
    /// </summary>
    public class ReturnMessage
    {
        [XmlElement("return_code")]
        public string Return_Code { get; set; }

        [XmlElement("return_msg")]
        public string Return_Msg { get; set; }

        public string ToXmlString()
        {
            return string.Format(@"<xml><return_code><![CDATA[{0}]]></return_code>
                    <return_msg><![CDATA[{1}]]></return_msg></xml>", Return_Code, Return_Msg);
        }
    }

四、退款

退款需要用到证书，配置WeiXinConst内证书相关常量再使用：

        /// <summary>
        /// 订单退款
        /// </summary>
        /// <param name="transaction_Id">微信交易单号</param>
        /// <param name="orderNo">我们自己的单号</param>
        /// <param name="totalFee">订单金额（分）</param>
        /// <param name="refundNo">退款单号（我们自己定义）</param>
        /// <param name="refundFee">退款金额（分）</param>
        /// <returns></returns>
        public bool UnifiedOrderRefund(string transaction_Id,string orderNo,string totalFee, string refundNo,string refundFee)
        {
            UnifiedWxPayModel model = UnifiedWxPayModel.CreateUnifiedModel(WeiXinConst.AppId, WeiXinConst.PartnerId, WeiXinConst.PartnerKey);
            string postData = model.CreateOrderRefundXml(orderNo, transaction_Id, totalFee, refundNo, refundFee);
            //退款需要用到证书， 要配置WeiXineConst CertPath 和 CertPwd
            return WeiXinHelper.Refund(postData, WeiXinConst.CertPath, WeiXinConst.CertPwd);
        }

创建订单退款Xml：

        #region 创建订单退款 XML
        /// <summary>
        /// 创建订单退款 XML
        /// </summary>
        /// <param name="orderNo">商户订单号</param>
        /// <param name="transactionId">微信订单号</param>
        /// <param name="totalFee">总金额</param>
        /// <param name="refundNo">退款订单号</param>
        /// <param name="refundFee">退款金额</param>
        /// <returns></returns>
        public string CreateOrderRefundXml(string orderNo, string transactionId, string totalFee, string refundNo, string refundFee)
        {
            Dictionary<string, string> nativeObj = new Dictionary<string, string>();

            nativeObj.Add("appid", AppId);
            nativeObj.Add("mch_id", WeiXinConst.PartnerId);
            nativeObj.Add("nonce_str", CommonUtil.CreateNoncestr());
            if (string.IsNullOrEmpty(transactionId))
            {
                if (string.IsNullOrEmpty(orderNo))
                    throw new Exception("缺少订单号！");
                nativeObj.Add("out_trade_no", orderNo);
            }
            else
            {
                nativeObj.Add("transaction_id", transactionId);
            }

            nativeObj.Add("out_refund_no", refundNo);
            nativeObj.Add("total_fee", totalFee);
            nativeObj.Add("refund_fee", refundFee);
            nativeObj.Add("op_user_id", PartnerId); //todo:配置

            nativeObj.Add("sign", GetCftPackage(nativeObj));

            return DictionaryToXmlString(nativeObj);
        }

        #endregion

WeiXinHelper中V3退款方法：

        #region V3 申请退款

        /// <summary>
        /// 申请退款（V3接口）
        /// </summary>
        /// <param name="postData">请求参数</param>
        /// <param name="certPath">证书路径</param>
        /// <param name="certPwd">证书密码</param>
        public static bool Refund(string postData, string certPath, string certPwd)
        {
            string url = WeiXinConst.WeiXin_Pay_UnifiedOrderRefundUrl;
            RefundMessage message = RefundHelper.PostXmlResponse<RefundMessage>(url, postData, certPath, certPwd);
            return message.Success;
        }

        #endregion

V3退款帮助类：

    /// <summary>
    /// V3退款帮助类
    /// </summary>
    public class RefundHelper
    {
        /// <summary>
        /// 证书验证的 post请求
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url">请求Url</param>
        /// <param name="postData">post数据</param>
        /// <param name="certPath">证书路径</param>
        /// <param name="certPwd">证书密码</param>
        /// <returns></returns>
        public static T PostXmlResponse<T>(string url, string postData, string certPath, string certPwd) where T : class
        {
            if (url.StartsWith("https"))
                System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;

            HttpWebRequest hp = (HttpWebRequest)WebRequest.Create(url);

            ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

            hp.ClientCertificates.Add(new X509Certificate2(certPath, certPwd));

            var encoding = System.Text.Encoding.UTF8;
            byte[] data = encoding.GetBytes(postData);

            hp.Method = "POST";

            hp.ContentType = "application/x-www-form-urlencoded";

            hp.ContentLength = data.Length;

            using (Stream ws = hp.GetRequestStream())
            {
                // 发送数据
                ws.Write(data, 0, data.Length);
                ws.Close();

                using (HttpWebResponse wr = (HttpWebResponse)hp.GetResponse())
                {
                    using (StreamReader sr = new StreamReader(wr.GetResponseStream(), encoding))
                    {
                        return HttpClientHelper.XmlDeserialize<T>(sr.ReadToEnd());
                    }
                }
            }
        }

        //验证服务器证书
        private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        }
    }

私有的方法：

1. Dictionary<string,string>转为XmlDocument 

           /// <summary>
           /// dictionary转为xml 字符串
           /// </summary>
           /// <param name="dic"></param>
           /// <returns></returns>
           private static string DictionaryToXmlString(Dictionary<string, string> dic)
           {
               StringBuilder xmlString = new StringBuilder();
               xmlString.Append("<xml>");
               foreach (string key in dic.Keys)
               {
                   xmlString.Append(string.Format("<{0}><![CDATA[{1}]]></{0}>", key, dic[key]));
               }
               xmlString.Append("</xml>");
               return xmlString.ToString();
           }

2. XmlDocument转为Dictionary<string,string> 

           /// <summary>
           /// xml字符串 转换为  dictionary
           /// </summary>
           /// <param name="document"></param>
           /// <returns></returns>
           public static Dictionary<string, string> XmlToDictionary(string xmlString)
           {
               System.Xml.XmlDocument document = new System.Xml.XmlDocument();
               document.LoadXml(xmlString);
   
               Dictionary<string, string> dic = new Dictionary<string, string>();
   
               var nodes = document.FirstChild.ChildNodes;
   
               foreach (System.Xml.XmlNode item in nodes)
               {
                   dic.Add(item.Name, item.InnerText);
               }
               return dic;
           }