GridView直接导Excel

/// <summary>
    /// 匯出到Excel
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnExport_Click(object sender, EventArgs e)
    {
        ExportGridViewToExcel(Response, GridView_trdord, "Tracing");
    }
    //到出excel
    public void ExportGridViewToExcel(HttpResponse response, Control gv, String excelFileName)
    {
        response.Clear();
        response.Buffer = true;
        response.Charset = "UTF-8";
        response.AppendHeader("Content-Disposition", string.Format("attachment;filename={0}.xls", excelFileName));
        response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");
        response.ContentType = "application/ms-excel";

        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);

        GridView_trdord.AllowPaging = false;//清除分页

        //gvEfficiency.AllowSorting = false; //清除排序     
        //SetReport();
        //控制GridView导出Excel后的样式
        this.GridView_trdord.GridLines = GridLines.Both;
        this.GridView_trdord.RenderControl(oHtmlTextWriter);

        Response.Output.Write(oStringWriter.ToString());
        Response.Flush();
        Response.End();
        //GridView1.AllowSorting = true; //恢复排序   
        GridView_trdord.AllowPaging = true;  //恢复排序
        //SetReport(); //再次绑定
    }

    //以下的代码务必要加在上面一段后面，否则会出现错误：
    //Control 'grdvExcel' of type 'GridView' must be placed inside a form tag with runat=server.
    public override void VerifyRenderingInServerForm(Control control)
    {
        // 覆盖VerifyRenderingInServerForm方法，非常重要，否则系统会报错
        //base.VerifyRenderingInServerForm(control);
    }