在asp.net中用以下代码导出execl时，如何设置execl的边框？

 private void ExportExcelFromDataGrid( string filename , System.Web.UI.WebControls.DataGrid ToExcelGrid )
        {
            Response.Clear();
            Response.Buffer=   true;     
            Response.Charset="utf-8";           
            Response.AppendHeader("Content-Disposition","attachment;filename="+Server.UrlEncode ( filename ) );     
            Response.ContentEncoding=System.Text.Encoding.Default;//设置输出流为简体中文   
            Response.ContentType   =   "application/ms-excel";//设置输出文件类型为excel文件。     
            this.EnableViewState   =   false;           
            System.Globalization.CultureInfo   myCItrad   =   new   System.Globalization.CultureInfo("ZH-CN",true);   
            System.IO.StringWriter   oStringWriter   =   new   System.IO.StringWriter(myCItrad);     
            System.Web.UI.HtmlTextWriter   oHtmlTextWriter   =   new   System.Web.UI.HtmlTextWriter(oStringWriter);   
            ToExcelGrid.RenderControl(oHtmlTextWriter);     
            Response.Write(oStringWriter.ToString());
            Response.End();
}