Below is code written for opening XLFile.
HttpContext.Current.Response.Clear();
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + astr_FileName);HttpContext.Current.Response.AddHeader("Content-Length", abyte_Data.Length.ToString());
HttpContext.Current.Response.ContentType = astr_ContentType; //octet-stream"; or //"application/vnd.ms-excel";
HttpContext.Current.Response.BinaryWrite(abyte_Data);
Udaya.M