asp.net导出成EXCEL

以下是导出的方法：
public static void ToExcel(System.Web.UI.Control ctl)
    {
        //HttpContext.Current.Response.Charset   ="GB2312";  
        HttpContext.Current.Response.Charset = "GBK";
        HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=memory.xls");
        HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GBK");
        HttpContext.Current.Response.ContentType = "application/ms-excel";//image/JPEG;text/HTML;image/GIF;vnd.ms-excel/msword  
       
        ctl.Page.EnableViewState = false;
       
        System.IO.StringWriter tw = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
       
        ctl.RenderControl(hw);
       
        HttpContext.Current.Response.Write(tw.ToString());
        HttpContext.Current.Response.End();
    }
在其它方法中调用：ToExcel(gridview1);