public static void DownLoadFile(HttpRequest _Request, HttpResponse _Response, string fileName, string fullPath)    {        FileInfo fileInfo = new FileInfo(fullPath);        if (fileInfo.Exists)        {            _Response.Clear();            _Response.ClearHeaders();            _Response.Buffer = false;            _Response.ContentType = "application/octet-stream";            _Response.ContentEncoding = Encoding.UTF8;            _Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);            _Response.AppendHeader("Content-Length", fileInfo.Length.ToString());            _Response.TransmitFile(fullPath, 0L, fileInfo.Length);            _Response.WriteFile(fileInfo.FullName);            _Response.Flush();            _Response.End();            _Response.Close();        }    }