public ActionResult Upload()    {      // var pathUrl = "http://" + Request.Url.Authority;      var file = Request.Files["Filedata"];      var uploadFileName = file.FileName;      string filePath = "/File/" + uploadFileName;      string AbsolutePath = Server.MapPath(filePath);      file.SaveAs(AbsolutePath);       //將上傳的東西保存           return Json(new { FileName = uploadFileName, FilePath = filePath });    }

 public ActionResult DownLoad(string FileName)    {      string fileName = FileName;//客戶端保存的文件名       string filePath = Server.MapPath("/File/"+ FileName);//路徑                                     //以字符流的形式下載文件         FileStream fs = new FileStream(filePath, FileMode.Open);      byte[] bytes = new byte[(int)fs.Length];      fs.Read(bytes, 0, bytes.Length);      fs.Close();      Response.ContentType = "application/octet-stream";      //通知瀏覽器下載文件而不是打開        Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));      Response.BinaryWrite(bytes);      Response.Flush();      Response.End();      return Json("");    }