private void Export(string contentType, string data, string fileName)
{
//EnableViewState = false;
HttpContext.Current.Response.Clear();
HttpContext.Current.Response.Buffer = true;
HttpContext.Current.Response.ContentType = contentType;
HttpContext.Current.Response.AddHeader("content-disposition", String.Format("attachment;filename={0}", fileName));
HttpContext.Current.Response.Write(data);
HttpContext.Current.Response.End();
}