NPOI使用

namespace ExcelTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var userList = GetUsers();
            var stream = RenderExcel(userList);
            SaveToFile(stream, "./1.xls");
        }

        static void SaveToFile(MemoryStream ms, string fileName)
        {
            using (FileStream fs = new FileStream(fileName, FileMode.Create))
            {
                byte[] data = ms.ToArray();
                fs.Write(data, 0, data.Length);
                fs.Flush();
            }
        }

        public static MemoryStream RenderExcel(List<User> userList)
        {
            MemoryStream ms = new MemoryStream();

            DataTable dt = new DataTable();

            var workBook = new HSSFWorkbook();
            var sheet = workBook.CreateSheet("Sheet1");
            var headerRow = sheet.CreateRow(0);
            var headerCell = headerRow.CreateCell(0);
            headerCell.SetCellValue("用户表");

            //headerCell样式
            ICellStyle style = workBook.CreateCellStyle();
            style.Alignment = HorizontalAlignment.Center;
            //
            var font = workBook.CreateFont();
            font.Boldweight = short.MaxValue;
            style.SetFont(font);
            headerCell.CellStyle = style;
            //
            headerRow.Height = 20 * 20;
            sheet.SetColumnWidth(0, 10 * 256);

            sheet.AddMergedRegion(new CellRangeAddress(0, 0, 0, 1));

            var captionRow = sheet.CreateRow(1);
            captionRow.CreateCell(0).SetCellValue("ID");
            captionRow.CreateCell(1).SetCellValue("名字");

            int rowIndex = 2;
            foreach (var user in userList)
            {
                var dataRow = sheet.CreateRow(rowIndex);

                dataRow.CreateCell(0).SetCellValue(user.Id);
                dataRow.CreateCell(1).SetCellValue(user.Name);

                rowIndex++;
            }
            workBook.Write(ms);
            ms.Flush();
            ms.Position = 0;
            return ms;
        }

        static List<User> GetUsers()
        {
            List<User> users = new List<User>
            {
                new User {Id=1,Name="qwe" },
                new User {Id=2,Name="wer" },
                new User {Id=3,Name="rty" },
                new User {Id=4,Name="tyu" },
                new User {Id=5,Name="uio" },
            };
            return users;
        }
    }

    class User
    {
        public int Id { get; set; }
        public string Name { get; set; }

    }
}