C# 使用NPOI导入Excel，不用安装Office及OLEDB，支持xls/xlsx， x86/x64

using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;

    public static class ExcelImporter
    {
        /// <summary>
        /// 根据sheet序号获取数据
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="sheetIndex"></param>
        /// <returns></returns>
        public static DataTable ImportByIndex(string fileName, int sheetIndex = 0)
        {
            using (FileStream fs = File.OpenRead(fileName))
            {
                IWorkbook book = null;
                if (fileName.ToLower().EndsWith("xls"))
                    book = new HSSFWorkbook(fs);
                if (fileName.ToLower().EndsWith("xlsx"))
                    book = new XSSFWorkbook(fs);

                var sheet = book.GetSheetAt(sheetIndex);
                if (sheet == null)
                    throw new Exception($"Can‘t find sheet at index of {sheetIndex}");
             
                return sheet.ToTable();
            }
        }

        /// <summary>
        /// 根据sheet名称获取数据
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="sheetName"></param>
        /// <returns></returns>
        public static DataTable ImportBySheetName(string fileName, string sheetName)
        {
            using (FileStream fs = File.OpenRead(fileName))
            {
                IWorkbook book = null;
                if (fileName.ToLower().EndsWith("xls"))
                    book = new HSSFWorkbook(fs);
                if (fileName.ToLower().EndsWith("xlsx"))
                    book = new XSSFWorkbook(fs);

                var sheet = book.GetSheet(sheetName);
                if (sheet == null)
                    throw new Exception($"Can‘t find sheet name of {sheetName}");

                return sheet.ToTable();
            }
        }

        /// <summary>
        /// 将sheet转化为DataTable
        /// </summary>
        /// <param name="sheet"></param>
        /// <returns></returns>
        private static DataTable ToTable(this ISheet sheet)
        {
            DataTable dt = new DataTable();
            var firstRow = sheet.GetRow(0);
            if (firstRow != null)
            {
                for (int columnIndex = 0; columnIndex < firstRow.LastCellNum; columnIndex++)
                {
                    var cell = firstRow.GetCell(columnIndex);
                    dt.Columns.Add(cell.StringCellValue.Trim(), typeof(string));
                }

                for (int rowIndex = 1; rowIndex < sheet.PhysicalNumberOfRows; rowIndex++)
                {
                    var row = sheet.GetRow(rowIndex);
                    if (row != null)
                    {
                        DataRow drNew = dt.NewRow();
                        for (int columnIndex = 0; columnIndex < firstRow.LastCellNum; columnIndex++)
                        {
                            drNew[columnIndex] = Convert.ToString(row.GetCell(columnIndex));
                        }
                        dt.Rows.Add(drNew);
                    }
                }
            }
            return dt;
        }
    }