Gridview 自动导出Excel问题

Question

在网上找到这么一段导出代码

  private void Export(string FileType, string FileName)
    {
        Response.Charset = "GB2312";
        Response.ContentEncoding = System.Text.Encoding.UTF8;
        Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FileName, Encoding.UTF8).ToString());
        Response.ContentType = FileType;
        this.EnableViewState = false;
      
        StringWriter tw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(tw);
        gvStat.RenderControl(hw);
        Response.Write(tw.ToString());
        Response.End();
    }

点击按钮时，执行 
Export("application/ms-excel", "测试.xls");

点击时，会弹出保存的提示。如何能直接保存，而不提示呢？比如，一点按钮，就直接保存到网站的根目录下。