.Net后台实现微信APP支付

上一节分享了微信小程序支付的后台，这一节来分享一下微信APP支付的后台。微信APP支付和微信小程序差别不大，微信APP支付后台不需要微信登录凭证、后台下单时交易类型（trade_type）不再是"JSAPI"，而是“APP”、商户后台传递给支付端的下单参数也有所不同。由于微信小程序支付和APP支付使用的APPID不同，索性直接写了两套支付，不再在代码里区分究竟该使用小程序支付的配置参数还是APP支付的参数。

官方是这样介绍的

具体实现：

在WePay文件夹下新建AppPay文件夹（微信支付的公共类在上一节），用于存放微信APP支付用到的类，新建AppPayConfig类

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Web.Configuration;

 namespace App.Pay.WePay.XcxPay
 {
     public class XcxPayConfig : WePayConfig
     {
         //=======【基本信息设置】=====================================
         /* 微信公众号信息配置
         * APPID：绑定支付的APPID（必须配置）
         * MCHID：商户号（必须配置）
         * KEY：商户支付密钥，参考开户邮件设置（必须配置）
         * APPSECRET：公众帐号secert（仅JSAPI支付的时候需要配置）
         */
         /// 小程序支付
         public static string APPID = WebConfigurationManager.AppSettings["XcxAppID"].ToString();
         public static string MCHID = WebConfigurationManager.AppSettings["XcxMchID"].ToString();
         public static string KEY = WebConfigurationManager.AppSettings["XcxKey"].ToString();
         public static string APPSECRET = WebConfigurationManager.AppSettings["XcxAppSecret"].ToString();

         //=======【证书路径设置】=====================================
         /* 证书路径,注意应该填写绝对路径（仅退款、撤销订单时需要）
         */
         public const string SSLCERT_PATH = "cert/apiclient_cert.p12";
         public const string SSLCERT_PASSWORD = "";

         //=======【支付结果通知url】=====================================
         /* 支付结果通知回调url，用于商户接收支付结果
         */
         public static string NOTIFY_URL = WebConfigurationManager.AppSettings["XcxNotifyUrl"].ToString();

         // log记录
         public static string LogPath = WebConfigurationManager.AppSettings["XcxLog"].ToString();
     }
 }

新建AppPayHttpService类

 using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Net;
 using System.Net.Security;
 using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Threading.Tasks;
 using System.Web;

 namespace App.Pay.WePay.AppPay
 {
     public class AppPayHttpService
     {
         private static Log Log = new Log(AppPayConfig.LogPath);

         public static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
         {
             //直接确认，否则打不开
             return true;
         }

         public static string Post(string xml, string url, bool isUseCert, int timeout)
         {
             System.GC.Collect();//垃圾回收，回收没有正常关闭的http连接

             string result = "";//返回结果

             HttpWebRequest request = null;
             HttpWebResponse response = null;
             Stream reqStream = null;

             try
             {
                 //设置最大连接数
                 ServicePointManager.DefaultConnectionLimit = ;
                 //设置https验证方式
                 if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
                 {
                     ServicePointManager.ServerCertificateValidationCallback =
                             new RemoteCertificateValidationCallback(CheckValidationResult);
                 }

                 /***************************************************************
                 * 下面设置HttpWebRequest的相关属性
                 * ************************************************************/
                 request = (HttpWebRequest)WebRequest.Create(url);

                 request.Method = "POST";
                 request.Timeout = timeout * ;

                 //设置代理服务器
                 //WebProxy proxy = new WebProxy();                          //定义一个网关对象
                 //proxy.Address = new Uri(WxPayConfig.PROXY_URL);              //网关服务器端口:端口
                 //request.Proxy = proxy;

                 //设置POST的数据类型和长度
                 request.ContentType = "text/xml";
                 byte[] data = System.Text.Encoding.UTF8.GetBytes(xml);
                 request.ContentLength = data.Length;

                 //是否使用证书
                 if (isUseCert)
                 {
                     string path = HttpContext.Current.Request.PhysicalApplicationPath;
                     X509Certificate2 cert = new X509Certificate2(path + AppPayConfig.SSLCERT_PATH, AppPayConfig.SSLCERT_PASSWORD);
                     request.ClientCertificates.Add(cert);
                     //Log.Debug("WxPayApi", "PostXml used cert");
                 }

                 //往服务器写入数据
                 reqStream = request.GetRequestStream();
                 reqStream.Write(data, , data.Length);
                 reqStream.Close();

                 //获取服务端返回
                 response = (HttpWebResponse)request.GetResponse();

                 //获取服务端返回数据
                 StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                 result = sr.ReadToEnd().Trim();
                 sr.Close();
             }
             catch (System.Threading.ThreadAbortException e)
             {
                 Log.Error("HttpService", "Thread - caught ThreadAbortException - resetting.");
                 Log.Error("Exception message: {0}", e.Message);
                 System.Threading.Thread.ResetAbort();
             }
             catch (WebException e)
             {
                 Log.Error("HttpService", e.ToString());
                 if (e.Status == WebExceptionStatus.ProtocolError)
                 {
                     Log.Error("HttpService", "StatusCode : " + ((HttpWebResponse)e.Response).StatusCode);
                     Log.Error("HttpService", "StatusDescription : " + ((HttpWebResponse)e.Response).StatusDescription);
                 }
                 throw new WePayException(e.ToString());
             }
             catch (Exception e)
             {
                 Log.Error("HttpService", e.ToString());
                 throw new WePayException(e.ToString());
             }
             finally
             {
                 //关闭连接和流
                 if (response != null)
                 {
                     response.Close();
                 }
                 if (request != null)
                 {
                     request.Abort();
                 }
             }
             return result;
         }

         /// <summary>
         /// 处理http GET请求，返回数据
         /// </summary>
         /// <param name="url">请求的url地址</param>
         /// <returns>http GET成功后返回的数据，失败抛WebException异常</returns>
         public static string Get(string url)
         {
             System.GC.Collect();
             string result = "";

             HttpWebRequest request = null;
             HttpWebResponse response = null;

             //请求url以获取数据
             try
             {
                 //设置最大连接数
                 ServicePointManager.DefaultConnectionLimit = ;
                 //设置https验证方式
                 if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
                 {
                     ServicePointManager.ServerCertificateValidationCallback =
                             new RemoteCertificateValidationCallback(CheckValidationResult);
                 }

                 /***************************************************************
                 * 下面设置HttpWebRequest的相关属性
                 * ************************************************************/
                 request = (HttpWebRequest)WebRequest.Create(url);

                 request.Method = "GET";

                 //设置代理
                 //WebProxy proxy = new WebProxy();
                 //proxy.Address = new Uri(WxPayConfig.PROXY_URL);
                 //request.Proxy = proxy;

                 //获取服务器返回
                 response = (HttpWebResponse)request.GetResponse();

                 //获取HTTP返回数据
                 StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                 result = sr.ReadToEnd().Trim();
                 sr.Close();
             }
             catch (System.Threading.ThreadAbortException e)
             {
                 Log.Error("HttpService", "Thread - caught ThreadAbortException - resetting.");
                 Log.Error("Exception message: {0}", e.Message);
                 System.Threading.Thread.ResetAbort();
             }
             catch (WebException e)
             {
                 Log.Error("HttpService", e.ToString());
                 if (e.Status == WebExceptionStatus.ProtocolError)
                 {
                     Log.Error("HttpService", "StatusCode : " + ((HttpWebResponse)e.Response).StatusCode);
                     Log.Error("HttpService", "StatusDescription : " + ((HttpWebResponse)e.Response).StatusDescription);
                 }
                 throw new WePayException(e.ToString());
             }
             catch (Exception e)
             {
                 Log.Error("HttpService", e.ToString());
                 throw new WePayException(e.ToString());
             }
             finally
             {
                 //关闭连接和流
                 if (response != null)
                 {
                     response.Close();
                 }
                 if (request != null)
                 {
                     request.Abort();
                 }
             }
             return result;
         }
     }
 }

新建AppPayData类

 using LitJson;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Security.Cryptography;
 using System.Text;
 using System.Threading.Tasks;
 using System.Xml;

 namespace App.Pay.WePay.AppPay
 {
     /// <summary>
     /// 微信支付协议接口数据类，所有的API接口通信都依赖这个数据结构，
     /// 在调用接口之前先填充各个字段的值，然后进行接口通信，
     /// 这样设计的好处是可扩展性强，用户可随意对协议进行更改而不用重新设计数据结构，
     /// 还可以随意组合出不同的协议数据包，不用为每个协议设计一个数据包结构
     /// </summary>
     public class AppPayData
     {
         private Log Log = new Log(AppPayConfig.LogPath);

         public AppPayData()
         {
         }

         //采用排序的Dictionary的好处是方便对数据包进行签名，不用再签名之前再做一次排序
         private SortedDictionary<string, object> m_values = new SortedDictionary<string, object>();

         /**
         * 设置某个字段的值
         * @param key 字段名
          * @param value 字段值
         */
         public void SetValue(string key, object value)
         {
             m_values[key] = value;
         }

         /**
         * 根据字段名获取某个字段的值
         * @param key 字段名
          * @return key对应的字段值
         */
         public object GetValue(string key)
         {
             object o = null;
             m_values.TryGetValue(key, out o);
             return o;
         }

         /**
          * 判断某个字段是否已设置
          * @param key 字段名
          * @return 若字段key已被设置，则返回true，否则返回false
          */
         public bool IsSet(string key)
         {
             object o = null;
             m_values.TryGetValue(key, out o);
             if (null != o)
                 return true;
             else
                 return false;
         }

         /**
         * @将Dictionary转成xml
         * @return 经转换得到的xml串
         * @throws WePayException
         **/
         public string ToXml()
         {
             //数据为空时不能转化为xml格式
             if ( == m_values.Count)
             {
                 Log.Error(this.GetType().ToString(), "WxPayData数据为空!");
                 throw new WePayException("WxPayData数据为空!");
             }

             string xml = "<xml>";
             foreach (KeyValuePair<string, object> pair in m_values)
             {
                 //字段值不能为null，会影响后续流程
                 if (pair.Value == null)
                 {
                     Log.Error(this.GetType().ToString(), "WxPayData内部含有值为null的字段!");
                     throw new WePayException("WxPayData内部含有值为null的字段!");
                 }

                 if (pair.Value.GetType() == typeof(int))
                 {
                     xml += "<" + pair.Key + ">" + pair.Value + "</" + pair.Key + ">";
                 }
                 else if (pair.Value.GetType() == typeof(string))
                 {
                     xml += "<" + pair.Key + ">" + "<![CDATA[" + pair.Value + "]]></" + pair.Key + ">";
                 }
                 else//除了string和int类型不能含有其他数据类型
                 {
                     Log.Error(this.GetType().ToString(), "WxPayData字段数据类型错误!");
                     throw new WePayException("WxPayData字段数据类型错误!");
                 }
             }
             xml += "</xml>";
             return xml;
         }

         /**
         * @将xml转为WxPayData对象并返回对象内部的数据
         * @param string 待转换的xml串
         * @return 经转换得到的Dictionary
         * @throws WePayException
         */
         public SortedDictionary<string, object> FromXml(string xml)
         {
             if (string.IsNullOrEmpty(xml))
             {
                 Log.Error(this.GetType().ToString(), "将空的xml串转换为WxPayData不合法!");
                 throw new WePayException("将空的xml串转换为WxPayData不合法!");
             }

             SafeXmlDocument xmlDoc = new SafeXmlDocument();
             xmlDoc.LoadXml(xml);
             XmlNode xmlNode = xmlDoc.FirstChild;//获取到根节点<xml>
             XmlNodeList nodes = xmlNode.ChildNodes;
             foreach (XmlNode xn in nodes)
             {
                 XmlElement xe = (XmlElement)xn;
                 m_values[xe.Name] = xe.InnerText;//获取xml的键值对到WxPayData内部的数据中
             }

             try
             {
                 //2015-06-29 错误是没有签名
                 if (m_values["return_code"] != "SUCCESS")
                 {
                     return m_values;
                 }
                 CheckSign();//验证签名,不通过会抛异常
             }
             catch (WePayException ex)
             {
                 throw new WePayException(ex.Message);
             }

             return m_values;
         }

         /**
         * @Dictionary格式转化成url参数格式
         * @ return url格式串, 该串不包含sign字段值
         */
         public string ToUrl()
         {
             string buff = "";
             foreach (KeyValuePair<string, object> pair in m_values)
             {
                 if (pair.Value == null)
                 {
                     Log.Error(this.GetType().ToString(), "WxPayData内部含有值为null的字段!");
                     throw new WePayException("WxPayData内部含有值为null的字段!");
                 }

                 if (pair.Key != "sign" && pair.Value.ToString() != "")
                 {
                     buff += pair.Key + "=" + pair.Value + "&";
                 }
             }
             buff = buff.Trim('&');
             return buff;
         }

         /**
         * @Dictionary格式化成Json
          * @return json串数据
         */
         public string ToJson()
         {
             string jsonStr = JsonMapper.ToJson(m_values);
             return jsonStr;
         }

         /**
         * @values格式化成能在Web页面上显示的结果（因为web页面上不能直接输出xml格式的字符串）
         */
         public string ToPrintStr()
         {
             string str = "";
             foreach (KeyValuePair<string, object> pair in m_values)
             {
                 if (pair.Value == null)
                 {
                     Log.Error(this.GetType().ToString(), "WxPayData内部含有值为null的字段!");
                     throw new WePayException("WxPayData内部含有值为null的字段!");
                 }

                 str += string.Format("{0}={1}<br>", pair.Key, pair.Value.ToString());
             }
             Log.Debug(this.GetType().ToString(), "Print in Web Page : " + str);
             return str;
         }

         /**
         * @生成签名，详见签名生成算法
         * @return 签名, sign字段不参加签名
         */
         public string MakeSign()
         {
             //转url格式
             string str = ToUrl();
             //在string后加入API KEY
             str += "&key=" + AppPayConfig.KEY;
             //MD5加密
             var md5 = MD5.Create();
             var bs = md5.ComputeHash(Encoding.UTF8.GetBytes(str));
             var sb = new StringBuilder();
             foreach (byte b in bs)
             {
                 sb.Append(b.ToString("x2"));
             }
             //所有字符转为大写
             return sb.ToString().ToUpper();
         }

         /**
         *
         * 检测签名是否正确
         * 正确返回true，错误抛异常
         */
         public bool CheckSign()
         {
             //如果没有设置签名，则跳过检测
             if (!IsSet("sign"))
             {
                 Log.Error(this.GetType().ToString(), "WxPayData签名存在但不合法!");
                 throw new WePayException("WxPayData签名存在但不合法!");
             }
             //如果设置了签名但是签名为空，则抛异常
             else if (GetValue("sign") == null || GetValue("sign").ToString() == "")
             {
                 Log.Error(this.GetType().ToString(), "WxPayData签名存在但不合法!");
                 throw new WePayException("WxPayData签名存在但不合法!");
             }

             //获取接收到的签名
             string return_sign = GetValue("sign").ToString();

             //在本地计算新的签名
             string cal_sign = MakeSign();

             if (cal_sign == return_sign)
             {
                 return true;
             }

             Log.Error(this.GetType().ToString(), "WxPayData签名验证错误!");
             throw new WePayException("WxPayData签名验证错误!");
         }

         /**
         * @获取Dictionary
         */
         public SortedDictionary<string, object> GetValues()
         {
             return m_values;
         }
     }
 }

新建AppPayNotify类

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Web;

 namespace App.Pay.WePay.AppPay
 {
     /// <summary>
     /// 回调处理基类
     /// 主要负责接收微信支付后台发送过来的数据，对数据进行签名验证
     /// 子类在此类基础上进行派生并重写自己的回调处理过程
     /// </summary>
     public class AppPayNotify
     {
         public HttpContext context { get; set; }
         public Log Log = new Log(AppPayConfig.LogPath);

         public AppPayNotify(HttpContext context)
         {
             this.context = context;
         }

         /// <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 AppPayData GetNotifyData()
         {
             //接收从微信后台POST过来的数据
             System.IO.Stream s = context.Request.InputStream;
             int count = ;
             byte[] buffer = new byte[];
             StringBuilder builder = new StringBuilder();
             while ((count = s.Read(buffer, , )) > )
             {
                 builder.Append(Encoding.UTF8.GetString(buffer, , count));
             }
             s.Flush();
             s.Close();
             s.Dispose();

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

         }
     }
 }

新建AppPayApi类

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace App.Pay.WePay.AppPay
 {
     public class AppPayApi
     {
         public static Log Log = new Log(AppPayConfig.LogPath);

         /**
         * 提交被扫支付API
         * 收银员使用扫码设备读取微信用户刷卡授权码以后，二维码或条码信息传送至商户收银台，
         * 由商户收银台或者商户后台调用该接口发起支付。
         * @param WxPayData inputObj 提交给被扫支付API的参数
         * @param int timeOut 超时时间
         * @throws WePayException
         * @return 成功时返回调用结果，其他抛异常
         */
         public static AppPayData Micropay(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/micropay";
             //检测必填参数
             if (!inputObj.IsSet("body"))
             {
                 throw new WePayException("提交被扫支付API接口中，缺少必填参数body！");
             }
             else if (!inputObj.IsSet("out_trade_no"))
             {
                 throw new WePayException("提交被扫支付API接口中，缺少必填参数out_trade_no！");
             }
             else if (!inputObj.IsSet("total_fee"))
             {
                 throw new WePayException("提交被扫支付API接口中，缺少必填参数total_fee！");
             }
             else if (!inputObj.IsSet("auth_code"))
             {
                 throw new WePayException("提交被扫支付API接口中，缺少必填参数auth_code！");
             }

             inputObj.SetValue("spbill_create_ip", WePayConfig.IP);//终端ip
             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", Guid.NewGuid().ToString().Replace("-", ""));//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名
             string xml = inputObj.ToXml();

             var start = DateTime.Now;//请求开始时间

             Log.Info("XcxPayApi", "MicroPay request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);//调用HTTP通信接口以提交数据到API
             Log.Info("XcxPayApi", "MicroPay response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);//获得接口耗时

             //将xml格式的结果转换为对象以返回
             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 查询订单
         * @param WxPayData inputObj 提交给查询订单API的参数
         * @param int timeOut 超时时间
         * @throws WePayException
         * @return 成功时返回订单查询结果，其他抛异常
         */
         public static AppPayData OrderQuery(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/orderquery";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no") && !inputObj.IsSet("transaction_id"))
             {
                 throw new WePayException("订单查询接口中，out_trade_no、transaction_id至少填一个！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名

             string xml = inputObj.ToXml();

             var start = DateTime.Now;

             Log.Info("XcxPayApi", "OrderQuery request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);//调用HTTP通信接口提交数据
             Log.Info("XcxPayApi", "OrderQuery response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);//获得接口耗时

             //将xml格式的数据转化为对象以返回
             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 撤销订单API接口
         * @param WxPayData inputObj 提交给撤销订单API接口的参数，out_trade_no和transaction_id必填一个
         * @param int timeOut 接口超时时间
         * @throws WePayException
         * @return 成功时返回API调用结果，其他抛异常
         */
         public static AppPayData Reverse(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/secapi/pay/reverse";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no") && !inputObj.IsSet("transaction_id"))
             {
                 throw new WePayException("撤销订单API接口中，参数out_trade_no和transaction_id必须填写一个！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名
             string xml = inputObj.ToXml();

             var start = DateTime.Now;//请求开始时间

             Log.Info("XcxPayApi", "Reverse request : " + xml);

             string response = AppPayHttpService.Post(xml, url, true, timeOut);

             Log.Info("XcxPayApi", "Reverse response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);

             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 申请退款
         * @param WxPayData inputObj 提交给申请退款API的参数
         * @param int timeOut 超时时间
         * @throws WePayException
         * @return 成功时返回接口调用结果，其他抛异常
         */
         public static AppPayData Refund(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/secapi/pay/refund";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no") && !inputObj.IsSet("transaction_id"))
             {
                 throw new WePayException("退款申请接口中，out_trade_no、transaction_id至少填一个！");
             }
             else if (!inputObj.IsSet("out_refund_no"))
             {
                 throw new WePayException("退款申请接口中，缺少必填参数out_refund_no！");
             }
             else if (!inputObj.IsSet("total_fee"))
             {
                 throw new WePayException("退款申请接口中，缺少必填参数total_fee！");
             }
             else if (!inputObj.IsSet("refund_fee"))
             {
                 throw new WePayException("退款申请接口中，缺少必填参数refund_fee！");
             }
             else if (!inputObj.IsSet("op_user_id"))
             {
                 throw new WePayException("退款申请接口中，缺少必填参数op_user_id！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", Guid.NewGuid().ToString().Replace("-", ""));//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名

             string xml = inputObj.ToXml();
             var start = DateTime.Now;

             Log.Info("XcxPayApi", "Refund request : " + xml);
             string response = AppPayHttpService.Post(xml, url, true, timeOut);//调用HTTP通信接口提交数据到API
             Log.Info("XcxPayApi", "Refund response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);//获得接口耗时

             //将xml格式的结果转换为对象以返回
             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 查询退款
         * 提交退款申请后，通过该接口查询退款状态。退款有一定延时，
         * 用零钱支付的退款20分钟内到账，银行卡支付的退款3个工作日后重新查询退款状态。
         * out_refund_no、out_trade_no、transaction_id、refund_id四个参数必填一个
         * @param WxPayData inputObj 提交给查询退款API的参数
         * @param int timeOut 接口超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData RefundQuery(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/refundquery";
             //检测必填参数
             if (!inputObj.IsSet("out_refund_no") && !inputObj.IsSet("out_trade_no") &&
                 !inputObj.IsSet("transaction_id") && !inputObj.IsSet("refund_id"))
             {
                 throw new WePayException("退款查询接口中，out_refund_no、out_trade_no、transaction_id、refund_id四个参数必填一个！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名

             string xml = inputObj.ToXml();

             var start = DateTime.Now;//请求开始时间

             Log.Info("XcxPayApi", "RefundQuery request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);//调用HTTP通信接口以提交数据到API
             Log.Info("XcxPayApi", "RefundQuery response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);//获得接口耗时

             //将xml格式的结果转换为对象以返回
             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         * 下载对账单
         * @param WxPayData inputObj 提交给下载对账单API的参数
         * @param int timeOut 接口超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData DownloadBill(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/downloadbill";
             //检测必填参数
             if (!inputObj.IsSet("bill_date"))
             {
                 throw new WePayException("对账单接口中，缺少必填参数bill_date！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名

             string xml = inputObj.ToXml();

             Log.Info("XcxPayApi", "DownloadBill request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);//调用HTTP通信接口以提交数据到API
             Log.Info("XcxPayApi", "DownloadBill result : " + response);

             AppPayData result = new AppPayData();
             //若接口调用失败会返回xml格式的结果
             if (response.Substring(, ) == "<xml>")
             {
                 result.FromXml(response);
             }
             //接口调用成功则返回非xml格式的数据
             else
                 result.SetValue("result", response);

             return result;
         }

         /**
         *
         * 转换短链接
         * 该接口主要用于扫码原生支付模式一中的二维码链接转成短链接(weixin://wxpay/s/XXXXXX)，
         * 减小二维码数据量，提升扫描速度和精确度。
         * @param WxPayData inputObj 提交给转换短连接API的参数
         * @param int timeOut 接口超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData ShortUrl(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/tools/shorturl";
             //检测必填参数
             if (!inputObj.IsSet("long_url"))
             {
                 throw new WePayException("需要转换的URL，签名用原串，传输需URL encode！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名
             inputObj.SetValue("device_info", "wxAPP");//设备名称
             string xml = inputObj.ToXml();

             var start = DateTime.Now;//请求开始时间

             Log.Info("XcxPayApi", "ShortUrl request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);
             Log.Info("XcxPayApi", "ShortUrl response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);

             AppPayData result = new AppPayData();
             result.FromXml(response);
             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 统一下单
         * @param WxPaydata inputObj 提交给统一下单API的参数
         * @param int timeOut 超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData UnifiedOrder(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no"))
             {
                 throw new WePayException("缺少统一支付接口必填参数out_trade_no！");
             }
             else if (!inputObj.IsSet("body"))
             {
                 throw new WePayException("缺少统一支付接口必填参数body！");
             }
             else if (!inputObj.IsSet("total_fee"))
             {
                 throw new WePayException("缺少统一支付接口必填参数total_fee！");
             }
             else if (!inputObj.IsSet("trade_type"))
             {
                 throw new WePayException("缺少统一支付接口必填参数trade_type！");
             }

             //关联参数
             if (inputObj.GetValue("trade_type").ToString() == "JSAPI" && !inputObj.IsSet("openid"))
             {
                 throw new WePayException("统一支付接口中，缺少必填参数openid！trade_type为JSAPI时，openid为必填参数！");
             }
             if (inputObj.GetValue("trade_type").ToString() == "NATIVE" && !inputObj.IsSet("product_id"))
             {
                 throw new WePayException("统一支付接口中，缺少必填参数product_id！trade_type为JSAPI时，product_id为必填参数！");
             }

             //异步通知url未设置，则使用配置文件中的url
             if (!inputObj.IsSet("notify_url"))
             {
                 inputObj.SetValue("notify_url", AppPayConfig.NOTIFY_URL);//异步通知url
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("spbill_create_ip", WePayConfig.IP);//终端ip
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串

             //签名
             inputObj.SetValue("sign", inputObj.MakeSign());
             string xml = inputObj.ToXml();

             var start = DateTime.Now;

             Log.Info("XcxPayApi", "UnfiedOrder request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);
             Log.Info("XcxPayApi", "UnfiedOrder response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);

             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 统一下单
         * @param WxPaydata inputObj 提交给统一下单API的参数
         * @param int timeOut 超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData UnifiedOrderApp(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no"))
             {
                 throw new WePayException("缺少统一支付接口必填参数out_trade_no！");
             }
             else if (!inputObj.IsSet("body"))
             {
                 throw new WePayException("缺少统一支付接口必填参数body！");
             }
             else if (!inputObj.IsSet("total_fee"))
             {
                 throw new WePayException("缺少统一支付接口必填参数total_fee！");
             }
             else if (!inputObj.IsSet("trade_type"))
             {
                 throw new WePayException("缺少统一支付接口必填参数trade_type！");
             }

             //关联参数
             if (inputObj.GetValue("trade_type").ToString() == "JSAPI" && !inputObj.IsSet("openid"))
             {
                 throw new WePayException("统一支付接口中，缺少必填参数openid！trade_type为JSAPI时，openid为必填参数！");
             }
             if (inputObj.GetValue("trade_type").ToString() == "NATIVE" && !inputObj.IsSet("product_id"))
             {
                 throw new WePayException("统一支付接口中，缺少必填参数product_id！trade_type为JSAPI时，product_id为必填参数！");
             }

             //异步通知url未设置，则使用配置文件中的url
             if (!inputObj.IsSet("notify_url"))
             {
                 inputObj.SetValue("notify_url", AppPayConfig.NOTIFY_URL);//异步通知url
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("spbill_create_ip", WePayConfig.IP);//终端ip
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串

             //签名
             inputObj.SetValue("sign", inputObj.MakeSign());
             string xml = inputObj.ToXml();

             var start = DateTime.Now;

             Log.Info("XcxPayApi", "UnfiedOrder request : " + xml);
             string response = AppPayHttpService.Post(xml, url, false, timeOut);
             Log.Info("XcxPayApi", "UnfiedOrder response : " + response);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);

             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 关闭订单
         * @param WxPayData inputObj 提交给关闭订单API的参数
         * @param int timeOut 接口超时时间
         * @throws WePayException
         * @return 成功时返回，其他抛异常
         */
         public static AppPayData CloseOrder(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/pay/closeorder";
             //检测必填参数
             if (!inputObj.IsSet("out_trade_no"))
             {
                 throw new WePayException("关闭订单接口中，out_trade_no必填！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名
             string xml = inputObj.ToXml();

             var start = DateTime.Now;//请求开始时间

             string response = AppPayHttpService.Post(xml, url, false, timeOut);

             var end = DateTime.Now;
             int timeCost = (int)((end - start).TotalMilliseconds);

             AppPayData result = new AppPayData();
             result.FromXml(response);

             ReportCostTime(url, timeCost, result);//测速上报

             return result;
         }

         /**
         *
         * 测速上报
         * @param string interface_url 接口URL
         * @param int timeCost 接口耗时
         * @param WxPayData inputObj参数数组
         */
         private static void ReportCostTime(string interface_url, int timeCost, AppPayData inputObj)
         {
             //如果不需要进行上报
             if (WePayConfig.REPORT_LEVENL == )
             {
                 return;
             }

             //如果仅失败上报
             if (WePayConfig.REPORT_LEVENL ==  && inputObj.IsSet("return_code") && inputObj.GetValue("return_code").ToString() == "SUCCESS" &&
              inputObj.IsSet("result_code") && inputObj.GetValue("result_code").ToString() == "SUCCESS")
             {
                 return;
             }

             //上报逻辑
             AppPayData data = new AppPayData();
             data.SetValue("interface_url", interface_url);
             data.SetValue("execute_time_", timeCost);
             //返回状态码
             if (inputObj.IsSet("return_code"))
             {
                 data.SetValue("return_code", inputObj.GetValue("return_code"));
             }
             //返回信息
             if (inputObj.IsSet("return_msg"))
             {
                 data.SetValue("return_msg", inputObj.GetValue("return_msg"));
             }
             //业务结果
             if (inputObj.IsSet("result_code"))
             {
                 data.SetValue("result_code", inputObj.GetValue("result_code"));
             }
             //错误代码
             if (inputObj.IsSet("err_code"))
             {
                 data.SetValue("err_code", inputObj.GetValue("err_code"));
             }
             //错误代码描述
             if (inputObj.IsSet("err_code_des"))
             {
                 data.SetValue("err_code_des", inputObj.GetValue("err_code_des"));
             }
             //商户订单号
             if (inputObj.IsSet("out_trade_no"))
             {
                 data.SetValue("out_trade_no", inputObj.GetValue("out_trade_no"));
             }
             //设备号
             if (inputObj.IsSet("device_info"))
             {
                 data.SetValue("device_info", inputObj.GetValue("device_info"));
             }

             try
             {
                 Report(data);
             }
             catch (WePayException ex)
             {
                 //不做任何处理
             }
         }

         /**
         *
         * 测速上报接口实现
         * @param WxPayData inputObj 提交给测速上报接口的参数
         * @param int timeOut 测速上报接口超时时间
         * @throws WePayException
         * @return 成功时返回测速上报接口返回的结果，其他抛异常
         */
         public static AppPayData Report(AppPayData inputObj, int timeOut = )
         {
             string url = "https://api.mch.weixin.qq.com/payitil/report";
             //检测必填参数
             if (!inputObj.IsSet("interface_url"))
             {
                 throw new WePayException("接口URL，缺少必填参数interface_url！");
             }
             if (!inputObj.IsSet("return_code"))
             {
                 throw new WePayException("返回状态码，缺少必填参数return_code！");
             }
             if (!inputObj.IsSet("result_code"))
             {
                 throw new WePayException("业务结果，缺少必填参数result_code！");
             }
             if (!inputObj.IsSet("user_ip"))
             {
                 throw new WePayException("访问接口IP，缺少必填参数user_ip！");
             }
             if (!inputObj.IsSet("execute_time_"))
             {
                 throw new WePayException("接口耗时，缺少必填参数execute_time_！");
             }

             inputObj.SetValue("appid", AppPayConfig.APPID);//公众账号ID
             inputObj.SetValue("mch_id", AppPayConfig.MCHID);//商户号
             inputObj.SetValue("user_ip", WePayConfig.IP);//终端ip
             inputObj.SetValue("time", DateTime.Now.ToString("yyyyMMddHHmmss"));//商户上报时间
             inputObj.SetValue("nonce_str", GenerateNonceStr());//随机字符串
             inputObj.SetValue("sign", inputObj.MakeSign());//签名
             string xml = inputObj.ToXml();

             Log.Info("XcxPayApi", "Report request : " + xml);

             string response = AppPayHttpService.Post(xml, url, false, timeOut);

             Log.Info("XcxPayApi", "Report response : " + response);

             AppPayData result = new AppPayData();
             result.FromXml(response);
             return result;
         }

         /**
         * 根据当前系统时间加随机序列来生成订单号
          * @return 订单号
         */
         public static string GenerateOutTradeNo()
         {
             var ran = new Random();
             return string.Format("{0}{1}{2}", AppPayConfig.MCHID, DateTime.Now.ToString("yyyyMMddHHmmss"), ran.Next());
         }

         /**
         * 生成时间戳，标准北京时间，时区为东八区，自1970年1月1日 0点0分0秒以来的秒数
          * @return 时间戳
         */
         public static string GenerateTimeStamp()
         {
             TimeSpan ts = DateTime.UtcNow - new DateTime(, , , , , , );
             return Convert.ToInt64(ts.TotalSeconds).ToString();
         }

         /**
         * 生成随机串，随机串包含字母或数字
         * @return 随机串
         */
         public static string GenerateNonceStr()
         {
             return Guid.NewGuid().ToString().Replace("-", "");
         }
     }
 }

接下来是业务类，注意业务类中不必再传微信登录凭证。

 using App.Common.Extension;
 using App.Pay.WePay.AppPay;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.Configuration;
 using System.Web.Mvc;

 namespace App.WebTest.Controllers
 {
     public class WeAppPayController : BaseController
     {
         /// <summary>
         /// 微信app支付
         /// </summary>
         /// <param name="oidStr">订单编号</param>
         /// <returns></returns>
         public ActionResult WxPayApp(string oidStr)
         {
             // App调用只能传参
             int[] oIds = Serialize.JsonTo<List<int>>(oidStr).ToArray();

             #region 验证订单是否有效

             decimal payPrice = ;
             string detail = "";

             /// 验证订单是否有效，并统计订单总金额
             /// ...

             #endregion

             #region 统一下单
             try
             {
                 //string userId = LoginUser.Id.ToString();
                 var address = WebConfigurationManager.AppSettings["WxAppNotifyUrl"].ToString();
                 AppPayData data = new AppPayData();
                 data.SetValue("body", "民政社工培训-课程购买");
                 //data.SetValue("attach", userId + "|" + String.Join(",", oIds).ToString());
                 data.SetValue("attach", String.Join(",", oIds).ToString());
                 Random rd = new Random();
                 var payNum = DateTime.Now.ToString("yyyyMMddHHmmss") + rd.Next(, ).ToString().PadLeft(, '');
                 data.SetValue("out_trade_no", payNum);
                 data.SetValue("detail", detail.Substring(, detail.Length - ));
                 data.SetValue("total_fee", Convert.ToInt32(payPrice * ));
                 data.SetValue("time_start", DateTime.Now.ToString("yyyyMMddHHmmss"));
                 data.SetValue("time_expire", DateTime.Now.AddMinutes().ToString("yyyyMMddHHmmss"));
                 data.SetValue("notify_url", address);

                 //注意，这里交易方式是APP
                 data.SetValue("trade_type", "APP");

                 AppPayData result = AppPayApi.UnifiedOrder(data);
                 var appid = "";
                 var partnerid = "";
                 var prepayid = "";
                 var package = "";
                 var nonceStr = "";
                 var timestamp = "";
                 var sign = "";
                 if (!result.IsSet("appid") || !result.IsSet("prepay_id") || result.GetValue("prepay_id").ToString() == "")
                 {
                     return Json(false, "下单失败！");
                 }
                 else
                 {
                     //统一下单
                     /// 修改订单状态
                     //OrderBll.Value.UpdateOrderApp(oIds, payNum);

                     appid = result.GetValue("appid").ToString();
                     nonceStr = result.GetValue("nonce_str").ToString();
                     partnerid = result.GetValue("mch_id").ToString();
                     prepayid = result.GetValue("prepay_id").ToString();
                     package = "Sign=WXPay";// "prepay_id=" + result.GetValue("prepay_id").ToString();
                 }
                 var signType = "MD5";
                 timestamp = ((DateTime.Now.Ticks - TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(, , )).Ticks) / ).ToString();
                 AppPayData applet = new AppPayData();
                 applet.SetValue("appid", appid);
                 applet.SetValue("noncestr", nonceStr);
                 applet.SetValue("package", package);
                 applet.SetValue("partnerid", partnerid);
                 applet.SetValue("prepayid", prepayid);
                 //applet.SetValue("signType", signType);
                 applet.SetValue("timestamp", timestamp);
                 sign = applet.MakeSign();
                 return Json(new { appid, partnerid, prepayid, package, nonceStr, timestamp, sign });
             }
             catch (Exception ex)
             {
                 return Json(false, "缺少参数");
             }

             #endregion

         }

         /// <summary>
         /// 微信支付回调
         /// </summary>
         /// <returns></returns>
         public string WxAppNotifyUrl()
         {
             Pay.Log Log = new Pay.Log(AppPayConfig.LogPath);
             Log.Info("WxAppNotifyUrl", "支付回调");
             AppPayNotify notify = new AppPayNotify(System.Web.HttpContext.Current);
             AppPayData notifyData = notify.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
                 AppPayData res = new AppPayData();
                 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());
                 Response.Write(res.ToXml());
                 Response.End();
             }

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

             //查询订单，判断订单真实性
             if (!AppQueryOrder(transaction_id))
             {
                 //若订单查询失败，则立即返回结果给微信支付后台
                 AppPayData res = new AppPayData();
                 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());

                 Response.Write(res.ToXml());
                 Response.End();
             }
             //查询订单成功
             else
             {
                 AppPayData res = new AppPayData();
                 res.SetValue("return_code", "SUCCESS");
                 res.SetValue("return_msg", "OK");
                 Log.Info(this.GetType().ToString(), "Order query success : " + res.ToXml());
                 Log.Info(this.GetType().ToString(), "Order query success,notifyData : " + notifyData.ToXml());
                 var returnCode = notifyData.GetValue("return_code").ToString();
                 var transactionNo = transaction_id;//微信订单号
                 var outTradeNo = notifyData.GetValue("out_trade_no").ToString();//自定义订单号
                 var attach = notifyData.GetValue("attach").ToString();//身份证
                 var endTime = notifyData.GetValue("time_end").ToString();//交易结束时间
                 //var body = notifyData.GetValue("body").ToString();//projectIdlist
                 var totalFee = notifyData.GetValue("total_fee").ToString(); ;//支付金额

                 int userId = Convert.ToInt32(attach.Split('|')[]);
                 string msg;
                 try
                 {
                     ///修改数据库订单状态
                     //var result = OrderBll.Value.CompleteWePay(userId, totalFee, transactionNo, returnCode, outTradeNo, attach, endTime, out msg);
                     var result = true;

                     Log.Info(this.GetType().ToString(), "CompleteWePay:" + result);
                 }
                 catch (Exception e)
                 {
                     Log.Error(this.GetType().ToString(), "CompleteWePay:" + e.ToString());
                 }

                 Response.Write(res.ToXml());
                 Response.End();
             }

             return "";
         }

         /// <summary>
         /// 查询订单
         /// </summary>
         /// <param name="transaction_id"></param>
         /// <returns></returns>
         private bool AppQueryOrder(string transaction_id)
         {
             AppPayData req = new AppPayData();
             req.SetValue("transaction_id", transaction_id);
             AppPayData res = AppPayApi.OrderQuery(req);
             if (res.GetValue("return_code").ToString() == "SUCCESS" && res.GetValue("result_code").ToString() == "SUCCESS")
             {
                 return true;
             }
             else
             {
                 return false;
             }
         }
     }
 }

源码：https://github.com/wenha/Utility.git