NPOI 2.2.1生成不正确的XLSX文件

Question

I have NPOI 2.2.1 and I realized that when generating XLSX file and opening with Excel 2013, a message box telling that a problem was encountered but Excel could try to recover from it. When I click "Yes", the sheet is finally shown.

This is the code:

        IWorkbook workbook = new XSSFWorkbook();
        ISheet sheet = workbook.CreateSheet(this.Title);

        using (var exportData = new MemoryStream())
        {
            workbook.Write(exportData);
            return exportData.GetBuffer();
        }

As you see, I am only creating the workbook, adding a sheet and then returning the bytes array. That array is stored in file using this code:

            string targetFile = System.IO.Path.Combine(System.IO.Path.GetTempPath(), String.Concat(btnExportar.Tag, "_", DateTime.Now.ToString("yyyyMMddHHmmss"), ".xlsx"));
            System.IO.File.WriteAllBytes(targetFile, xls.GetExcelData());

With XLS files there is no problem.

Regards Jaime

Answer 1

The problem is not with NPOI, but with your use of GetBuffer() . That is not the method you want to use for this purpose, as GetBuffer() returns the raw buffer underlying the memory stream (usually oversized), without cutting it off at the current position of the stream . This will leave uninitialized data at the end, causing the error message in Excel.

The get all the bytes from a MemoryStream, use ToArray() :

using (var exportData = new MemoryStream())
{
    workbook.Write(exportData);
    // return exportData.GetBuffer();
    return exportData.ToArray();
}