/// <summary>  /// 根據Excel格式讀取Excel  /// </summary>  /// <param name="stream">文件流</param>  /// <param name="type">Excel格式枚舉類型，xls/xlsx</param>  /// <param name="sheetName">表名，默認取第一張</param>  /// <returns>DataTable</returns>  private static DataTable ImportExcel(Stream stream, ExcelExtType type, string sheetName)  {    DataTable dt = new DataTable();    IWorkbook workbook;    try    {      //xls使用HSSFWorkbook類實現，xlsx使用XSSFWorkbook類實現      switch (type)      {        case ExcelExtType.xlsx:          workbook = new XSSFWorkbook(stream);          break;        default:          workbook = new HSSFWorkbook(stream);          break;      }      ISheet sheet = null;      //獲取工作表 默認取第一張      if (string.IsNullOrWhiteSpace(sheetName))        sheet = workbook.GetSheetAt(0);      else        sheet = workbook.GetSheet(sheetName);      if (sheet == null)        return null;      IEnumerator rows = sheet.GetRowEnumerator();      #region 獲取表頭      IRow headerRow = sheet.GetRow(0);      int cellCount = headerRow.LastCellNum;      for (int j = 0; j < cellCount; j++)      {        ICell cell = headerRow.GetCell(j);        if (cell != null)        {          dt.Columns.Add(cell.ToString());        }        else        {          dt.Columns.Add("");        }      }      #endregion      #region 獲取內容      for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)      {        IRow row = sheet.GetRow(i);        DataRow dataRow = dt.NewRow();        for (int j = row.FirstCellNum; j < cellCount; j++)        {          if (row.GetCell(j) != null)          {            //判斷單元格是否為日期格式            if (row.GetCell(j).CellType == NPOI.SS.UserModel.CellType.Numeric && HSSFDateUtil.IsCellDateFormatted(row.GetCell(j)))            {              if (row.GetCell(j).DateCellValue.Year >=1970)              {                dataRow[j] = row.GetCell(j).DateCellValue.ToString();              }              else              {                dataRow[j] = row.GetCell(j).ToString();              }            }            else            {              dataRow[j] = row.GetCell(j).ToString();            }          }        }        dt.Rows.Add(dataRow);      }      #endregion    }    catch (Exception ex)    {      dt=null;    }    finally    {      //if (stream != null)      //{      //  stream.Close();      //  stream.Dispose();      //}    }    return dt;  }

  /// <summary>  /// 上傳Excel導入  /// </summary>  /// <param name="file">上載文件對象</param>  /// <param name="errorMsg">錯誤信息</param>  /// <param name="sheetName">表名，默認取第一張</param>  /// <returns></returns>  public static DataTable Import(System.Web.HttpPostedFileBase file, ref string errorMsg, string sheetName = "")  {    if (file == null || file.InputStream == null || file.InputStream.Length == 0)    {      errorMsg = "請選擇要導入的Excel文件";      return null;    }    var excelType = GetExcelFileType(file.FileName);    if (excelType == null)    {      errorMsg = "請選擇正確的Excel文件";      return null;    }    using (var stream = new MemoryStream())    {      file.InputStream.Position = 0;      file.InputStream.CopyTo(stream);      var dt = ImportExcel(stream, excelType.Value, sheetName);      if (dt == null)        errorMsg = "導入失敗,請選擇正確的Excel文件";      return dt;    }  }

  /// <summary>  /// 根據文件路徑導入Excel  /// </summary>  /// <param name="filePath"></param>  /// <param name="errorMsg">錯誤信息</param>  /// <param name="sheetName">表名，默認取第一張</param>  /// <returns>可能為null的DataTable</returns>  public static DataTable Import(string filePath, ref string errorMsg, string sheetName = "")  {    var excelType = GetExcelFileType(filePath);    if (GetExcelFileType(filePath) == null)    {      errorMsg = "請選擇正確的Excel文件";      return null;    }    if (!File.Exists(filePath))    {      errorMsg = "沒有找到要導入的Excel文件";      return null;    }    DataTable dt;    using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))    {      dt = ImportExcel(stream, excelType.Value, sheetName);    }    if (dt == null)      errorMsg = "導入失敗,請選擇正確的Excel文件";    return dt;  }