protected void btnPrint_Click(object sender, EventArgs e)
    {
        string strPath = "MFOut" + DateTime.Now.ToString("yyyymmddhhmmssfff") + ".xls";
        DataGrid dg = new DataGrid();
        dg.DataSource = dtMain;
        dg.DataBind();
        Response.Clear();
        Response.AddHeader("content-disposition", "attachment;filename=" + strPath + "");
        Response.Charset = "gb2312";
        Response.ContentEncoding = System.Text.Encoding.UTF8;//不設置會有亂碼
        Response.ContentType = "application/vnd.xls";
        System.IO.StringWriter stringWrite = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
        dg.RenderControl(htmlWrite);
        Response.Write(stringWrite.ToString());
        Response.End();
    }
    public override void VerifyRenderingInServerForm(Control control)
    {
        //這個方法不能刪除掉 導出時要用到，不然會報錯：
        //類型“GridView”的控件“ctl00_ContentPlaceHolder1_GridView1”必須放在具有 runat=server 的窗體標記內(nèi)
    }