DevExpress ASPxUploadControl上传文件完成后如何提示上传成功以及终止上传

Question

//循环控件中的文件上传到服务器
            foreach (UploadedFile file in Upload.UploadedFiles)
            {
                //判断文件名不为空(不能为空格)
                if (!string.IsNullOrEmpty(file.FileName.Trim()) && file.IsValid)
                {
                    //上传文件根目录+当前上传文件类型目录
                    string dir = "\\\\" + fileServerIp + serverRoot;
                    //新建文件夹
                    string folderName = "OBS\\" + DateTime.Now.ToString("yyyy-MM-dd") + "_" + Guid.NewGuid().ToString();
                    //创建文件夹
                    CreateDirectory(dir, folderName, driverName, userName, passWord);
                    //上传文件完整路径
                    string filePath = driverName + folderName + "\\" + file.FileName;
                    file.SaveAs(filePath);
                    //文件服务器物理路径
                    physicalPath = physicalPath + serverRoot + folderName + "\\" + file.FileName;                    //将路径保存到数据库
                    HQIT.FEAZERP.DAL.SYS_XMLConvert_DAL xmlConvertDal = new HQIT.FEAZERP.DAL.SYS_XMLConvert_DAL();
                    var dal = new UDP_Service_DAL();
                    string xmlId;
                    xmlConvertDal.OrderInsertByOBS(filePath, out xmlId, ID, physicalPath, ddlOrderType.SelectedValue, ddlOrderReason.SelectedValue, ddlServer.SelectedValue);
                    dal.ConnectServer();
                    if (dal.IsConnect)
                    {
                        Dictionary<string, object> dic = new Dictionary<string, object>();
                        dic.Add("UserID", ID);
                        dic.Add("Lang", language);
                        dal.Send_OBS(dic);
                        dal.Closed();
                    }
                }
如上代码,我想在这之前上传时判断如果下拉列表没选则不让他上传,如果上传完成则弹出框框上传完成.现在两个都实现不了啊...ViewState也会丢值...