NPOI生成EXCEL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NPOI.HSSF.UserModel;
using NPOI.POIFS.FileSystem;
using NPOI.SS.UserModel;
using NPOI.SS.Util;
using NPOI.HSSF.Util;
using NPOI.HSSF.UserModel.Contrib;
using System.IO;

namespace ConsoleApplication7
{
    class Class11
    {
        static void Main(string[] args)
        {
            HSSFWorkbook book = new HSSFWorkbook();
            Sheet sheet = book.CreateSheet("bb");
            FileStream fs = new FileStream(@"C:\Users\jim\Desktop\aaa\aa.xls", FileMode.OpenOrCreate);

            for (int i = 0; i < 10; i++)
            {
                Row row = sheet.CreateRow(i);
                for (int j = 0; j < 10; j++)
                {
                    Cell cell = row.CreateCell(j);
                    cell.SetCellValue(10);

                    CellStyle cs = book.CreateCellStyle();
                    cs.BorderLeft = CellBorderType.THIN;
                    cs.BorderBottom = CellBorderType.THIN;
                    cs.BorderRight = CellBorderType.THIN;
                    cs.BorderTop = CellBorderType.THIN;
                    cs.FillBackgroundColor = HSSFColor.RED.index;
                    cs.FillForegroundColor = HSSFColor.RED.index;
                    cell.CellStyle = cs;
                    
                }
            }
            book.Write(fs);
            fs.Close();
        }
    }
}