GridView导出 Excel文件内容出现乱码

 Response.Charset = "GB2312";
            Response.Charset = "";
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ".xls\"");
            Response.ContentType = "application/ms-excel";
            Response.Write("<meta http-equiv=Content-Type content=\"text/html; charset=GB2312\">");

            System.IO.StringWriter oStringWriter = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
            xPanel.RenderControl(oHtmlTextWriter);
            Response.Write(oStringWriter.ToString());
            Response.End();

//以下不加也没报错，有的说要加上

public override void VerifyRenderingInServerForm(Control control)
    {
        //base.VerifyRenderingInServerForm(control);
    }