C#导出Excel

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Text;
using System.IO;

namespace CreateXML
{
    public partial class getExcel : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void BuildExcel()
        {
            DataSet ds = new DataSet();
            ds = PublicClass.OperatorSql.returnDS("select * from Equipment_Card");
            GridView gv = new GridView();
            gv.DataSource = ds;
            gv.DataBind();

            string filename = DateTime.Now.ToString("yyyyMMdd") + ".xls";
            Response.AppendHeader("Content-Disposition", "attachment;filename="
                + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8) + ";charset=gb2312)");
            Response.ContentType = "application/ms-excel";
            StringWriter sw = new StringWriter();
            HtmlTextWriter htw = new HtmlTextWriter(sw);
            gv.RenderControl(htw);
            Response.Write(sw.ToString());
            Response.End();
            Response.Clear();
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            BuildExcel();
        }
    }
}