Cannot access a closed stream (NPOI Library)

Question

I am using the following code to create an excel file using NPOI library. I am getting "Cannot access a closed stream" error. I have gone through a few threads and tried to implement the suggestions, but its not working.

XSSFWorkbook wb = null;
using (FileStream file = new FileStream("D:\\Test_Output.xlsx",
                                        FileMode.Open, FileAccess.Read))
{
    wb = new XSSFWorkbook(file);
}

MemoryStream mstream = new MemoryStream();
wb.Write(mstream);

FileStream xfile = new FileStream(Path.Combine(taskpath, "Test_Output.xlsx"),
                                  FileMode.OpenOrCreate, System.IO.FileAccess.Write);

byte[] bytes = new byte[mstream.Length];
mstream.Read(bytes, 0, (int)mstream.Length);
xfile.Write(bytes, 0, bytes.Length);
xfile.Close();
mstream.Close();

Kindly help me out in this regard.

Thanks

What exactly are you trying to achieve in your sample? It looks slightly far from real application. If you want to get bytes of xlsx file content - you can read it directly from disk without using NPOI for opening file and then writing it back to memory stream. Workbook method `Write` closes the stream implicitly, and it is unavoidable (see [this discussion](http://apache-poi.1045710.n5.nabble.com/XSSFWorkbook-write-OutputStream-closes-the-stream-td4870079.html)) — Andrey Korneyev, Jul 17 '15 at 07:27
I think you need to reset position `mstream.Position = 0;`, then you can invoke `mstream.Read` — cshu, Jul 17 '15 at 08:35

score 0 · Answer 1 · answered Jul 11 '16 at 13:16

int index=0;
XSSFWorkbook  wb = new XSSFWorkbook();
ISheet sheet = wb.CreateSheet("First Sheet");
  crow = sheet.CreateRow(rowindex);
            crow.HeightInPoints = 50;
            string Title = "[Case : " + "Demonstration Database for Clients" + "]\n" + "Productivity Report";
            ccel = crow.CreateCell(0);
            ccel.SetCellValue(Title);
            ccel.CellStyle = hstyle;
            ccel.CellStyle.WrapText = true;
            cra = new CellRangeAddress(rowindex, rowindex, 0, 14);
            sheet.AddMergedRegion(cra);
            rowindex++;
 FileStream sw = File.Create("d://header.xlsx");
            wb.Write(sw);
            sw.Close();
            MessageBox.Show("File Create");

score 0 · Answer 2 · answered May 14 '17 at 17:56

0

you do not need the memory stream try something like

 string excelLocation = Path.Combine(taskpath, "Test_Output.xlsx");
 FileStream sw = File.Create(excelLocation);

 wb.Write(sw);

 sw.Close();

answered May 14 '17 at 17:56

Sarah Akram

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Cannot access a closed stream (NPOI Library)

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