public void OutPutExcel(string filename)

        {

            //定义文档类型、字符编码 

            Response.Clear();

            Response.Buffer = true;

            Response.Charset = "GB2312";

            //下面这行很重要， attachment 参数表示作为附件下载，您可以改成 online在线打开 

            //filename=FileFlow.xls 指定输出文件的名称，注意其扩展名和指定文件类型相符，可以为：.doc 　　 .xls 　　 .txt 　　.htm 

            Response.AppendHeader("Content-Disposition", "attachment;filename=" + filename);

            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");

            //Response.ContentType指定文件类型 可以为application/ms-excel、application/ms-word、application/ms-txt、application/ms-html 或其他浏览器可直接支持文档 

            Response.ContentType = "application/ms-excel";

            this.EnableViewState = false;

            //　定义一个输入流 

            System.IO.StringWriter oStringWriter = new System.IO.StringWriter();

            System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);

            this.GridView1.RenderControl(oHtmlTextWriter);

            //this.RenderControl(oHtmlTextWriter); 

            //this 表示输出本页，你也可以绑定datagrid,或其他支持obj.RenderControl()属性的控件 

            Response.Write(oStringWriter.ToString());

            Response.End();

        }

        public override void VerifyRenderingInServerForm(Control control)

        {

            // Confirms that an HtmlForm control is rendered for

        }