public ActionResult DownloadFile(string id)

        {

            var fileinfo = CommonAnnexService.Get(id);

            if (fileinfo.StatusValue == (long)PublicStatusEnum.正常)

            {

                if (System.IO.File.Exists(Server.MapPath(fileinfo.SavePath)))

                {

                    return File(Server.MapPath(fileinfo.SavePath), "application/octet-stream", fileinfo.AnnexName +"."+ fileinfo.AnnexType);

                }

                return Fail("该文件已丢失");

            }

            return Fail("该文件已被删除");

        }