用于阅读 XLS 的 NPOI

Question

I am working on some project where I use NPOI library for reading some data from excel. Everything was working good but then I tried to read .xls and it stopped working. (Everything was well for .xlsx).

The last thing i tried is this:

 IWorkbook hssfwb;
                using (FileStream file = new FileStream(@filePath, FileMode.Open, FileAccess.Read))
                {
                     hssfwb = WorkbookFactory.Create(file);
                }

The exception I get is:

Your stream was neither an OLE2 stream, nor an OOXML stream.

What I need is a way to open .xls files using NPOI library. Thanks in advance.

Answer 1

To operate with the old Excel 97-2003 format (Files ending with ".xls"), you can use the HSSFWorkbook class.

If you check the file name's extension, you can handle both file types when reading the file into a IWorkbook model:

        MemoryStream fileStream = new MemoryStream(fileContent);
        IWorkbook workbook = null;

        if (fileName.ToLower().EndsWith(".xlsx"))
        {
            // new OOXML format
            workbook = new XSSFWorkbook(fileStream);
        }
        else
        {
            // old Excel 97 format
            workbook = new HSSFWorkbook(fileStream);
        }

From ther on you can handle the content of the spreadsheet as usual:

        // get first sheet
        ISheet sheet = workbook.GetSheetAt(0);

        // get header names as string array
        IRow headerRow = sheet.GetRow(rowNumber);
        List<ICell> headerCells = headerRow.Cells;
        List<string> rowData = new List<string>();
        foreach (ICell cell in headerCells)
        {
            rowData.Add(cell.ToString());
        }