关于Asp.net中导出Excel表格的问题

        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();
        }

        private void Button4_Click(object sender, System.EventArgs e)
        ...{
            this.Panel1.Visible = false;            
            string filename = "内训师.xls";
            this.DataGrid1.Columns[6].Visible = true;
            this.DataGrid1.Columns[7].Visible = true;
            this.DataGrid1.Columns[this.DataGrid1.Columns.Count-1].Visible = false;  // *
            this.DataGrid1.Columns[this.DataGrid1.Columns.Count-2].Visible = false;  // *
            this.DataGrid1.AllowSorting = false;  // *
            this.DataGrid1.AllowPaging = false; 
            this.DataGrid1.SelectedIndex = -1;    // *
            this.BindGrid();
            this.ExportExcelFromDataGrid ( filename , this.DataGrid1 );
        }
    }