Creating zip using java and make it downloadable

Question

I have this program which I am trying to use to create a zip file of the file located in the directory.

The program runs but in chrome it fails to download by saying the network error.

In Mozilla, it says Ut0ij4ld.ZIP.part could not be saved, because the source file could not be read.

what am I doing wrong, is there a better approach to do this?

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    String path = "D:\\Test\\";
    File directory = new File(path);
    String[] files = directory.list();

    //check if directories have files
    if (files != null && files.length > 0) {

        //create zip stream
        byte[] zip = zipFiles(directory, files);


        // Sends the response back to the user / browser with zip content
        ServletOutputStream sos = response.getOutputStream();
        response.setContentType("application/zip");
        response.setHeader("Content-Disposition", "attachment; filename=\"DATA.ZIP\"");

        sos.write(zip);
        sos.flush();
    }

    request.setAttribute("DownloadMessage", "Successfully");
    request.getRequestDispatcher("DownloadZipFile.jsp").forward(request, response);

}

private byte[] zipFiles(File directory, String[] files) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ZipOutputStream zos = new ZipOutputStream(baos);
    byte bytes[] = new byte[4096];

    for (String fileName : files) {
        try (FileInputStream fis = new FileInputStream(directory.getPath()
                + "/" + fileName);

                BufferedInputStream bis = new BufferedInputStream(fis)) {

            zos.putNextEntry(new ZipEntry(fileName));

            int bytesRead;
            while ((bytesRead = bis.read(bytes)) != -1) {
                zos.write(bytes, 0, bytesRead);
            }
            zos.closeEntry();
        }
    }
    zos.flush();
    baos.flush();
    zos.close();
    baos.close();

    return baos.toByteArray();
}

Answer 1

This works,

 @Override
protected void doGet( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    //set the content type to zip
    response.setContentType("application/zip");
    response.setHeader("Content-Disposition", "attachment; filename=\"DATA.ZIP\"");

    //to write it over http
    ServletOutputStream ouputStream = response.getOutputStream();

    //for writing files in the ZIP file format. Includes support for both compressed and uncompressed entries
    ZipOutputStream zos= new ZipOutputStream(ouputStream);

    //your file root folder
    File rootFolder= new File ("D:\\Test\\") ;

    // Looping through all the files

    for (File file: rootFolder.listFiles()){
        try {
            writeToZip(zos,file);
        } catch (Exception ex) {
            Logger.getLogger(Zipper.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    zos.close();
    ouputStream.close();
}



private static void writeToZip(ZipOutputStream zos,File file) throws Exception{


    FileInputStream fis=new FileInputStream(file);
    ZipEntry zipEntry= new ZipEntry(file.getName());
    zos.putNextEntry(zipEntry);

    final byte[] bytes = new byte[1024];
    int length;
    while ((length = fis.read(bytes)) >= 0) {
        zos.write(bytes, 0, length);
    }
    zos.closeEntry();
    fis.close();

} }