Question

I am trying to add some files to a ZIP file, it creates the file but does not add anything into it.
Code 1:

String fulldate = year + "-" + month + "-" + day + "-" + min;

File dateFolder = new File("F:\\" + compname + "\\" + fulldate);
dateFolder.mkdir();

String zipName = "F:\\" + compname + "\\" + fulldate + "\\" + fulldate + ".zip";

zipFolder(tobackup, zipName);

My function:

public static void zipFolder(File folder, String name) throws Exception {
    byte[] buffer = new byte[18024];

    ZipOutputStream out = new ZipOutputStream(new FileOutputStream(name));
    FileInputStream in = new FileInputStream(folder);

    out.putNextEntry(new ZipEntry(name));

    int len;

    while((len = in.read(buffer)) > 0) {
        out.write(buffer, 0, len);
    }

    out.closeEntry();
    in.close();
    out.close();
}

Edit: I found the problem, it was just having trouble writing files from the C:\ drive into a ZIP in the F:\ drive

Answer 1

You can’t zip folders, only files. To zip folders, you have to add all the subfiles manually. I wrote this class that does the job. You can have it for free 🙂

The usage would be this:

List<File> sources = new ArrayList<File>();
sources.add(tobackup);
Packager.packZip(new File(zipName), sources);

Here is the class:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.zip.Deflater;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class Packager
{
    public static void packZip(File output, List<File> sources) throws IOException
    {
        System.out.println("Packaging to " + output.getName());
        ZipOutputStream zipOut = new ZipOutputStream(new FileOutputStream(output));
        zipOut.setLevel(Deflater.DEFAULT_COMPRESSION);

        for (File source : sources)
        {
            if (source.isDirectory())
            {
                zipDir(zipOut, "", source);
            } else
            {
                zipFile(zipOut, "", source);
            }
        }
        zipOut.flush();
        zipOut.close();
        System.out.println("Done");
    }

    private static String buildPath(String path, String file)
    {
        if (path == null || path.isEmpty())
        {
            return file;
        } else
        {
            return path + "/" + file;
        }
    }

    private static void zipDir(ZipOutputStream zos, String path, File dir) throws IOException
    {
        if (!dir.canRead())
        {
            System.out.println("Cannot read " + dir.getCanonicalPath() + " (maybe because of permissions)");
            return;
        }

        File[] files = dir.listFiles();
        path = buildPath(path, dir.getName());
        System.out.println("Adding Directory " + path);

        for (File source : files)
        {
            if (source.isDirectory())
            {
                zipDir(zos, path, source);
            } else
            {
                zipFile(zos, path, source);
            }
        }

        System.out.println("Leaving Directory " + path);
    }

    private static void zipFile(ZipOutputStream zos, String path, File file) throws IOException
    {
        if (!file.canRead())
        {
            System.out.println("Cannot read " + file.getCanonicalPath() + " (maybe because of permissions)");
            return;
        }

        System.out.println("Compressing " + file.getName());
        zos.putNextEntry(new ZipEntry(buildPath(path, file.getName())));

        FileInputStream fis = new FileInputStream(file);

        byte[] buffer = new byte[4092];
        int byteCount = 0;
        while ((byteCount = fis.read(buffer)) != -1)
        {
            zos.write(buffer, 0, byteCount);
            System.out.print('.');
            System.out.flush();
        }
        System.out.println();

        fis.close();
        zos.closeEntry();
    }
}

Enjoy!

EDIT: To check if the program is still busy, you can add the three lines I marked with a (*)

EDIT 2: Try the new code. On my platform, it runs correct (OS X). I’m not sure but, there might be some limited read permissions for files in Windows in AppData.