How to make it as downloadable excel file using se

Question

I am reading a txt file and writing it into excel file, but while making it as downloadable excel file it is not writing any data to excel and giving showing this message

logic for downloading into excel

response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-Disposition", "attachment; filename=sampleName.xls");
    String path = getServletContext().getRealPath(file);
    File file = new File(path);
    System.out.println("File:" + file);
    FileInputStream is = new FileInputStream(uploadFilePath
            + File.separator + file.getName());
    try {
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        ArrayList<ArrayList<String>> exceldata = new ArrayList<ArrayList<String>>();
        ArrayList<String> headerRow = new ArrayList<String>();
        headerRow.add("Date and Time");
        headerRow.add("NMEA Message Type");
        headerRow.add("Fragments in the message");
        headerRow.add("Fragments no");
        headerRow.add("AIS MessageType");
        headerRow.add("Repeat Indicator");
        headerRow.add("MMSI Number");
        headerRow.add("AIS Version");
        headerRow.add("IMO Number");
        headerRow.add("Navigational status");
        headerRow.add("Rate Of Turn(ROT)");
        headerRow.add("Speed Over Ground(SOG)");
        headerRow.add("Position Accuracy(PA)");
        headerRow.add("Longitude");
        headerRow.add("Latitude");
        headerRow.add("Course Over Ground(COG)");
        headerRow.add("Heading(HDG)");
        headerRow.add("Time Stamp");
        exceldata.add(headerRow);
        String strLine;
        while ((strLine = br.readLine()) != null) {
            System.out.println(strLine);
            exceldata.add(decodeAisData(strLine));
        }
        writeDataToExcelFile("praveen",exceldata);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        try {
            is.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

For writing the data to excel:

private void writeDataToExcelFile(String string, ArrayList<ArrayList<String>> excelData) {
    HSSFWorkbook myWorkBook = new HSSFWorkbook();
    String sheetName = "";
    sheetName = "Document-" + 0;
    HSSFSheet mySheet = myWorkBook.createSheet(sheetName);                  
    HSSFRow myRow = null;
    HSSFCell myCell = null;
    for (int rowNum = 0; rowNum < excelData.size(); rowNum++) {
        ArrayList<String> rowData = excelData.get(rowNum);
        myRow = mySheet.createRow(rowNum);
        for (int cellNum = 0; cellNum < rowData.size(); cellNum++) {
            myCell = myRow.createCell(cellNum);
            myCell.setCellValue(rowData.get(cellNum));
        }
    }
    try {
        FileOutputStream out = new FileOutputStream("my.xls");
        myWorkBook.write(out);
        out.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

So please give solution to make as it as downloadable.Thanks

Answer 1

I would strongly discourage implementing this on your own, since you are very likely forget some special cases, for example concerning different separators, special characters, ...

Instead, use one of the many existing libraries for that.

Answer 2

Your writeDataToExcelFile method writes the Excel data into a FileOutputStream - this is not connected to the response OutputStream.

You should update the writeDataToExcelFile method to include another parameter:

private void writeDataToExcelFile(String string, 
                                  ArrayList<ArrayList<String>> excelData,
                                  OutputStream outputStream) 

and the writing of the data, change to this:

myWorkBook.write(outputStream);

This should then permit the myWorkBook object to write back to the browser.

Also, change the line that calls the method to:

writeDataToExcelFile("praveen",exceldata, response.getOutputStream());