C#使用NPOI上传excel

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

 public DataTable GetexcelDataSet(string path, Stream fs)
  {
   IWorkbook workbook = null;
   if (path.IndexOf(".xlsx") > 0)
   {
    workbook = new XSSFWorkbook(fs);//excel的版本2007
   }
   else if (path.IndexOf(".xls") > 0)
   {
    workbook = new HSSFWorkbook(fs);//excel的版本2003
   }
   ISheet sheet = workbook.GetSheetAt(0);//得到第一张表
   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

   for (int i = headerRow.FirstCellNum; i