post请求json内容丢失问题

今天在项目组用json传输数据 post方法提交 发现传输过去的数据json内的+ 号被直接干掉了.

后来传输之前直接先编码.

接收端:

   public void ProcessRequest(HttpContext context)
         {
             ReturnResult result = new ReturnResult();
             var method = context.Request.QueryString["method"].ToString();

             byte[] byts = new byte[HttpContext.Current.Request.InputStream.Length];
             HttpContext.Current.Request.InputStream.Read(byts, , byts.Length);
             string req = System.Text.Encoding.Default.GetString(byts);
             req = HttpContext.Current.Server.UrlDecode(req);

             //string p = @"\d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2}";
             //MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertDateStringToJsonDate);
             //Regex reg = new Regex(p);
             //req = reg.Replace(req, matchEvaluator);

             try
             {
                 if (context.Request.Params.Count > )
                 {

                     if (!string.IsNullOrEmpty(method))
                     {
                         switch (method)
                         {

                             case DTKeys.URL_PARM_METHOD_SENDMESSAGEREMIND://来自用户信息认证的 附件上传
                                 ContactMsg m = JsonHelper.FromJson<ContactMsg>(req);
                                 SendMessageRemind(m);
                                 break;

                             default:
                                 break;
                         }
                     }
                 }
                 else
                 {
                     result.Status = false;
                     result.Msg = "未检测的有效文件信息,或者您未登录";
                 }
             }
             catch (Exception ex)
             {
                 result.Status = false;
                 result.Msg = ex.Message;
                 Log4netHelper.WriteExceptionLog("Beta.ProductMarket.Web.Product.SendMsgToWX.ashx", ex);
             }
             context.Response.Clear();
             context.Response.ContentType = "text/html; charset=utf-8";
             context.Response.Write(JsonConvert.SerializeObject(result));
         }