GridView gridview = new GridView();                gridview.DataSource = dt;                gridview.DataBind();                string filename = LevelSupBaseInfoDropDownList.SelectedItem.Text;                Response.Clear();                Response.Buffer = true;                Response.Charset = "GB2312";                Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlPathEncode(filename + ".xls"));                Response.ContentEncoding = System.Text.Encoding.UTF7;                Response.ContentType = "application/ms-excel";                System.IO.StringWriter oStringWriter = new System.IO.StringWriter();                System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);                gridview.RenderControl(oHtmlTextWriter);                Response.Output.Write(oStringWriter.ToString());                Response.Flush();                Response.End();