asp.net C#将文档或控件dataGrid输出为Excel文档下载

        private void Page_Load(object sender, System.EventArgs e)
        {
            DataSet ds = new DataSet();
            sqlDataAdapter1.Fill(ds);
            DataGrid1.DataSource = ds;
            DataGrid1.DataBind();
        }

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下载按钮代码如下：
        private void Button1_Click(object sender, System.EventArgs e)
        {
            //1.定义文档类型、字符编码
            Response.Clear();
　　        Response.Buffer= true;
　　        Response.Charset="utf-8";

            //attachment 参数表示作为附件下载，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
            Response.AppendHeader("Content-Disposition","online;filename=FileFlow.xls");
            Response.ContentEncoding=System.Text.Encoding.GetEncoding("utf-8");

            //application/ms-excel, application/ms-word, application/ms-txt, application/ms-html
            Response.ContentType = "application/ms-excel";
            DataGrid1.EnableViewState = false;

            //2.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);

            //3.目标数据绑定到输入流输出
            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();
        }

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        public void ExportExcel(DataTable dt, string fileName)
        {
            Response.AppendHeader("Content-Disposition", "attachment;filename=fileName.xls");
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            Response.ContentType = "application/ms-excel";

            DataGrid dgExport = new DataGrid();
            dgExport.DataSource = dt;
            dgExport.DataBind();

            System.IO.StringWriter strWriter = new System.IO.StringWriter();
            HtmlTextWriter htmlWriter = new HtmlTextWriter(strWriter);
            dgExport.RenderControl(htmlWriter);
            Response.Clear();
            Response.Write(@"<meta http-equiv=""Content-Type"" content=""text/html; charset=gb2312"" />");
            Response.Write(strWriter.ToString());
            Response.End();
        }