How to unzip files recursively in Java?

Question

I have zip file which contains some other zip files.

For example, the mail file is abc.zip and it contains xyz.zip, class1.java

Answer 1

Modified as i needed then mixed in a bit of the best answers. This version will:

• Recursively Extract a zip to given location

• Create empty directories

• Close zip properly

---

public static void unZipAll(File source, File destination) throws IOException 
{
    System.out.println("Unzipping - " + source.getName());
    int BUFFER = 2048;

    ZipFile zip = new ZipFile(source);
    try{
        destination.getParentFile().mkdirs();
        Enumeration zipFileEntries = zip.entries();

        // Process each entry
        while (zipFileEntries.hasMoreElements())
        {
            // grab a zip file entry
            ZipEntry entry = (ZipEntry) zipFileEntries.nextElement();
            String currentEntry = entry.getName();
            File destFile = new File(destination, currentEntry);
            //destFile = new File(newPath, destFile.getName());
            File destinationParent = destFile.getParentFile();

            // create the parent directory structure if needed
            destinationParent.mkdirs();

            if (!entry.isDirectory())
            {
                BufferedInputStream is = null;
                FileOutputStream fos = null;
                BufferedOutputStream dest = null;
                try{
                    is = new BufferedInputStream(zip.getInputStream(entry));
                    int currentByte;
                    // establish buffer for writing file
                    byte data[] = new byte[BUFFER];

                    // write the current file to disk
                    fos = new FileOutputStream(destFile);
                    dest = new BufferedOutputStream(fos, BUFFER);

                    // read and write until last byte is encountered
                    while ((currentByte = is.read(data, 0, BUFFER)) != -1) {
                        dest.write(data, 0, currentByte);
                    }
                } catch (Exception e){
                    System.out.println("unable to extract entry:" + entry.getName());
                    throw e;
                } finally{
                    if (dest != null){
                        dest.close();
                    }
                    if (fos != null){
                        fos.close();
                    }
                    if (is != null){
                        is.close();
                    }
                }
            }else{
                //Create directory
                destFile.mkdirs();
            }

            if (currentEntry.endsWith(".zip"))
            {
                // found a zip file, try to extract
                unZipAll(destFile, destinationParent);
                if(!destFile.delete()){
                    System.out.println("Could not delete zip");
                }
            }
        }
    } catch(Exception e){
        e.printStackTrace();
        System.out.println("Failed to successfully unzip:" + source.getName());
    } finally {
        zip.close();
    }
    System.out.println("Done Unzipping:" + source.getName());
}

Answer 2

Here's some untested code base on some old code I had that unzipped files.

public void doUnzip(String inputZip, String destinationDirectory)
        throws IOException {
    int BUFFER = 2048;
    List zipFiles = new ArrayList();
    File sourceZipFile = new File(inputZip);
    File unzipDestinationDirectory = new File(destinationDirectory);
    unzipDestinationDirectory.mkdir();

    ZipFile zipFile;
    // Open Zip file for reading
    zipFile = new ZipFile(sourceZipFile, ZipFile.OPEN_READ);

    // Create an enumeration of the entries in the zip file
    Enumeration zipFileEntries = zipFile.entries();

    // Process each entry
    while (zipFileEntries.hasMoreElements()) {
        // grab a zip file entry
        ZipEntry entry = (ZipEntry) zipFileEntries.nextElement();

        String currentEntry = entry.getName();

        File destFile = new File(unzipDestinationDirectory, currentEntry);
        destFile = new File(unzipDestinationDirectory, destFile.getName());

        if (currentEntry.endsWith(".zip")) {
            zipFiles.add(destFile.getAbsolutePath());
        }

        // grab file's parent directory structure
        File destinationParent = destFile.getParentFile();

        // create the parent directory structure if needed
        destinationParent.mkdirs();

        try {
            // extract file if not a directory
            if (!entry.isDirectory()) {
                BufferedInputStream is =
                        new BufferedInputStream(zipFile.getInputStream(entry));
                int currentByte;
                // establish buffer for writing file
                byte data[] = new byte[BUFFER];

                // write the current file to disk
                FileOutputStream fos = new FileOutputStream(destFile);
                BufferedOutputStream dest =
                        new BufferedOutputStream(fos, BUFFER);

                // read and write until last byte is encountered
                while ((currentByte = is.read(data, 0, BUFFER)) != -1) {
                    dest.write(data, 0, currentByte);
                }
                dest.flush();
                dest.close();
                is.close();
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
    zipFile.close();

    for (Iterator iter = zipFiles.iterator(); iter.hasNext();) {
        String zipName = (String)iter.next();
        doUnzip(
            zipName,
            destinationDirectory +
                File.separatorChar +
                zipName.substring(0,zipName.lastIndexOf(".zip"))
        );
    }

}

Answer 3

One should CLOSE zip file after unzip.

static public void extractFolder(String zipFile) throws ZipException, IOException 
{
    System.out.println(zipFile);
    int BUFFER = 2048;
    File file = new File(zipFile);

    ZipFile zip = new ZipFile(file);
    try
    { 
       ...code from other answers ( ex. NeilMonday )...
    }
    finally
    {
        zip.close();
    }
}