微信支付退款

    public string Wxzhifurefund(string orderid,string openid,string weiId,string refund_fee)
        {
            Wxrefund refund = new Wxrefund();
            try { 
                //查询微商城appid
                string sql = "select * from pay_info where Enable=1";//必须保证enable=1唯一
                DataTable paydata = SQLiteDBHelper.GetDataTable(sql, weiId);
                if (paydata.Rows.Count > 0) //大于0,用户已设置相关信息
                {
                    //处理
                    refund.appid = paydata.Rows[0]["Appid"].ToString();//公众号ID
                    refund.mch_id = paydata.Rows[0]["Mchid"].ToString();//商户号
                    Setkey = paydata.Rows[0]["KeyValue"].ToString();//商户key
                }
                else {
                    writeLogs.writelog("微支付退款时,查询商户配置参数错误 请检查参数是否正确");
                    return "{\"errcode\":\"3\"}";//商户未设置支付参数
                }
                refund.nonce_str = openid;//随机字符串
                refund.out_trade_no = orderid;//商户订单号
                refund.out_refund_no =SystemSettingController.ConvertDateTimeInt(DateTime.Now);//创建退款订单号
                //使用订单编号,查询订单总金额
                sql = string.Format( "select * from order_info where orderid={0} and OpenId=‘{1}‘",orderid,openid);//必须保证订单号唯一性
                DataTable orderdata = SQLiteDBHelper.GetDataTable(sql, weiId);
                refund.total_fee = Convert.ToString(float.Parse(orderdata.Rows[0]["Receivables"].ToString()) * 100);//订单总金额
                if (string.IsNullOrEmpty(refund_fee))//退款金额等于空,就退全款 默认写入订单总金额
                {
                    refund.refund_fee = Convert.ToString(float.Parse(orderdata.Rows[0]["Receivables"].ToString()) * 100);//退款金额
                }
                else {
                    refund.refund_fee = refund_fee;//退款金额单位:分
                }
                refund.op_user_id = refund.appid;//默认商户号
                //字典排序
                Dictionary<string, string> dicrefund = new Dictionary<string, string>();
                dicrefund.Add("appid", refund.appid);
                dicrefund.Add("mch_id", refund.mch_id);
                dicrefund.Add("nonce_str", refund.nonce_str);
                dicrefund.Add("out_trade_no",refund.out_trade_no );
                dicrefund.Add("out_refund_no",refund.out_refund_no);
                dicrefund.Add("total_fee",refund.total_fee);
                dicrefund.Add("refund_fee",refund.refund_fee);
                dicrefund.Add("op_user_id", refund.op_user_id);
                dicrefund.Add("sign", WxSignCreate(dicrefund));
                //转换xml
                string xml = WxXml(dicrefund);
                string url = "https://api.mch.weixin.qq.com/secapi/pay/refund";
                //设置证书路径,密码
                string cert = @"xxxxx";
                string password = "xxxxxx";
                X509Certificate x509 = new X509Certificate(cert,password);
                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
                request.ClientCertificates.Add(x509);
                 //传输post数据
                var encoding = System.Text.Encoding.UTF8;
                byte[] databyte = encoding.GetBytes(xml);
                request.Method = "post";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = databyte.Length;
                using (Stream responstream = request.GetRequestStream())
                {
                    responstream.Write(databyte, 0, databyte.Length);
                    responstream.Close();
                }
                HttpWebResponse response =(HttpWebResponse)request.GetResponse();
                Stream stream = response.GetResponseStream();
                string result = string.Empty;
                using (StreamReader reader = new StreamReader(stream))
                {
                    result = reader.ReadToEnd();
                    writeLogs.writelog("退款接口返回结果:"+result);
                }
                //反序列化
                refund_return refunreturn = null;
                XmlSerializer refundxml = new XmlSerializer(typeof(refund_return));
                using (StringReader stringreader = new StringReader(result))
                {
                    refunreturn = refundxml.Deserialize(stringreader) as refund_return;
                }
                if (refunreturn.result_code == "" || refunreturn.result_code == null)
                {
                    writeLogs.writelog("退款失败,失败原因:"+ refunreturn.return_msg);
                    return "{\"errcode\":\"18\"}";//退款失败
                }
                if (refunreturn.result_code == "SUCCESS")//退款申请成功
                {
                        //处理退款操作


                }
                else if (refunreturn.result_code == "FAIL")//退款申请失败
                {
                    writeLogs.writelog("退款申请失败,错误码:"+refunreturn.err_code+",失败原因:" + refunreturn.err_code_des);
                    return "{\"errcode\":\"18\"}";//退款申请失败
                }


            }
            catch (Exception e)
            {
                writeLogs.writelog("微信支付退款异常,参数:订单号:"+orderid+",openid编号:"+openid+",公众号编号:"+weiId);
                writeLogs.writelog("退款异常打印:"+e.Message);
                return "{\"errcode\":\"18\"}";//退款失败
            }
            return "";//返回成功信息
        }