/// <summary>
  /// 把数据从Excel装载到DataTable
  /// </summary>
  /// <param name="pathName">带路径的Excel文件名</param>
  /// <param name="sheetName">工作表名</param>
  /// <param name="tbContainer">将数据存入的DataTable</param>
  /// <returns></returns>
  public DataTable ExcelToDataTable(string pathName, string sheetName)
  {
    DataTable tbContainer = new DataTable();
    string strConn = string.Empty;
    if (string.IsNullOrEmpty(sheetName)) { sheetName = "Sheet1"; }
    FileInfo file = new FileInfo(pathName);
    if (!file.Exists) { throw new Exception("文件不存在"); }
    string extension = file.Extension;
    switch (extension)
    {
      case ".xls":
        strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathName + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";
        break;
      case ".xlsx":
        strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + pathName + ";Extended Properties='Excel 12.0;HDR=Yes;IMEX=1;'";
        break;
      default:
        strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathName + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";
        break;
    }
    //链接Excel
    OleDbConnection cnnxls = new OleDbConnection(strConn);
    //读取Excel里面有 表Sheet1
    OleDbDataAdapter oda = new OleDbDataAdapter(string.Format("select * from [{0}$]", sheetName), cnnxls);
    DataSet ds = new DataSet();
    //将Excel里面有表内容装载到内存表中！
    oda.Fill(tbContainer);
    return tbContainer;
  }