asp.net 调用NPOI 输出Excel

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.IO;
using NPOI.HSSF.UserModel;
using NPOI.HPSF;
using NPOI.POIFS.FileSystem;
using NPOI.SS.UserModel;

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

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            string filename="test.xls";
            Response.ContentType = "application/vnd.ms-excel";
            Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}",filename));
            Response.Clear();

            InitializeWorkbook();
            GenerateData();            
            Response.BinaryWrite(WriteToStream().GetBuffer());
            Response.End();
        }

        HSSFWorkbook hssfworkbook;

        MemoryStream WriteToStream()
        {
            //Write the stream data of workbook to the root directory
            MemoryStream file = new MemoryStream();
            hssfworkbook.Write(file);
            return file;
        }

        void GenerateData()
        {
            ISheet sheet1 = hssfworkbook.CreateSheet("Sheet1");

            sheet1.CreateRow(0).CreateCell(0).SetCellValue("This is a Sample");
            int x = 1;
            for (int i = 1; i <= 15; i++)
            {
                IRow row = sheet1.CreateRow(i);
                for (int j = 0; j < 15; j++)
                {
                    row.CreateCell(j).SetCellValue(x++);
                }
            }
        }

        void InitializeWorkbook()
        {
            hssfworkbook = new HSSFWorkbook();

            ////create a entry of DocumentSummaryInformation
            DocumentSummaryInformation dsi = PropertySetFactory.CreateDocumentSummaryInformation();
            dsi.Company = "NPOI Team";
            hssfworkbook.DocumentSummaryInformation = dsi;

            ////create a entry of SummaryInformation
            SummaryInformation si = PropertySetFactory.CreateSummaryInformation();
            si.Subject = "NPOI SDK Example";
            hssfworkbook.SummaryInformation = si;
        }
    }
}