NPOI 导入excel

应用NUget 安装NPOI 很方便

读出excel的主要语句是

XSSFWorkbook hssfworkbook;

using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                {
                    hssfworkbook = new XSSFWorkbook(file);
                }

当excel以xlsx结尾用  XSSFWorkbook 否则用HSSFWorkbook

  public DataTable ImportExcelFile(string filePath)
        {
            XSSFWorkbook hssfworkbook;
            #region//初始化信息
            try
            {
                using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                {
                    hssfworkbook = new XSSFWorkbook(file);
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            #endregion
            NPOI.SS.UserModel.ISheet sheet = hssfworkbook.GetSheetAt(0);
            //using (NPOI.SS.UserModel.ISheet sheet = hssfworkbook.GetSheetAt(0))
            //{
                DataTable table = new DataTable();
                IRow headerRow = sheet.GetRow(0);//第一行为标题行
                int cellCount = headerRow.LastCellNum;//LastCellNum = PhysicalNumberOfCells
                int rowCount = sheet.LastRowNum;//LastRowNum = PhysicalNumberOfRows - 1

                //handling header.
                for (int i = headerRow.FirstCellNum; i < cellCount; i++)
                {
                    DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
                    table.Columns.Add(column);
                }
                for (int i = (sheet.FirstRowNum + 1); i <= rowCount; i++)
                {
                    IRow row = sheet.GetRow(i);
                    DataRow dataRow = table.NewRow();

                    if (row != null)
                    {
                        for (int j = row.FirstCellNum; j < cellCount; j++)
                        {
                            if (row.GetCell(j) != null)
                                dataRow[j] = GetCellValue(row.GetCell(j));
                        }
                    }

                    table.Rows.Add(dataRow);
                }
                return table;
            //}

        }
        /// <summary>
        /// 根据Excel列类型获取列的值
        /// </summary>
        /// <param name="cell">Excel列</param>
        /// <returns></returns>
        private static string GetCellValue(ICell cell)
        {
            if (cell == null)
                return string.Empty;
            switch (cell.CellType)
            {
                case CellType.Blank:
                    return string.Empty;
                case CellType.Boolean:
                    return cell.BooleanCellValue.ToString();
                case CellType.Error:
                    return cell.ErrorCellValue.ToString();
                case CellType.Numeric:
                case CellType.Unknown:
                default:
                    return cell.ToString();//This is a trick to get the correct value of the cell. NumericCellValue will return a numeric value no matter the cell value is a date or a number
                case CellType.String:
                    return cell.StringCellValue;
                case CellType.Formula:
                    try
                    {
                        HSSFFormulaEvaluator e = new HSSFFormulaEvaluator(cell.Sheet.Workbook);
                        e.EvaluateInCell(cell);
                        return cell.ToString();
                    }
                    catch
                    {
                        return cell.NumericCellValue.ToString();
                    }
            }
        }