/// <summary>
        /// 银联网关支付退款
        /// </summary>
        /// <param name="newUnionId">新的银联订单编号</param>
        /// <param name="queryIdUnion">要退款的银联流水编号</param>
        /// <param name="orderRefundDate">当前退款操作时间</param>
        /// <param name="payAmount">要退款的金额</param>
        /// <param name="_bank"></param>
        /// <returns></returns>
        public static bool UnionOnlineRefund(string newUnionId, string queryIdUnion, DateTime orderRefundDate, decimal payAmount, BankDomains _bank)
        {
            bool flag = false;
            try
            {
                UPOPSrv.LoadConf(new MemoryStream(byteBuffer));
                var param = new Dictionary<string, string>();

                param["transType"] = UPOPSrv.TransType.REFUND;
                param["orderNumber"] = RefundPre() + newUnionId;
                long amtInt = (int)(payAmount * 100);
　　　　　　　　　　//这个参数让我好找。。。
                param["origQid"] = queryIdUnion;
                param["orderAmount"] = amtInt.ToString();
                param["orderCurrency"] = UPOPSrv.CURRENCY_CNY;
                param["orderTime"] = orderRefundDate.ToString("yyyyMMddHHmmss");
                param["customerIp"] = _bank.ClientIP();

                param["frontEndUrl"] = "http://www.baidu.cn/";
                param["backEndUrl"] = "http://www.baidu.cn/";

                var srv = new BackPaySrv(param);
                var resp = srv.Request();
                if (resp == null)
                {
                    return flag;
                }
                if (resp.ResponseCode == "00")
                {
                    flag = true;
                }
                else
                {
                    var logger = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
                    logger.Error("退款失败代码：
" + JsonConvert.SerializeObject(resp));
                }
            }
            catch (Exception ex)
            {
                var logger = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
                logger.Error("错误信息：
" + ex.ToString());
            }
            return flag;
        }

  <payParams>
    <string>version</string>
    <string>charset</string>
    <string>transType</string>
    <string>origQid</string>
    <string>merId</string>
    <string>merAbbr</string>
    <string>acqCode</string>
    <string>merCode</string>
    <string>commodityUrl</string>
    <string>commodityName</string>
    <string>commodityUnitPrice</string>
    <string>commodityQuantity</string>
    <string>commodityDiscount</string>
    <string>transferFee</string>
    <string>orderNumber</string>
    <string>orderAmount</string>
    <string>orderCurrency</string>
    <string>orderTime</string>
    <string>customerIp</string>
    <string>customerName</string>
    <string>defaultPayType</string>
    <string>defaultBankNumber</string>
    <string>transTimeout</string>
    <string>frontEndUrl</string>
    <string>backEndUrl</string>
    <string>merReserved</string>
  </payParams>