How to use ZipFile Class in Java to recursively open all files including those under Folders

aruuuuu Published at Dev

aruuuuu

I am creating a method in Java to open a zipfile and process Excel files in the zip dynamically. I am using the API ZipFile in Java and would like to process the zipfile as is in memory without extracting it to the file system.

So far I am able to iterate through the zip file but am having trouble listing the files underneath a directory in the zip file. Excel files can be in a folder in the zip file. Below is my current code with a comment in the section that I am having trouble with. Any help is greatly appreciated :)

public static void main(String[] args) {
    try {
        ZipFile zip = new ZipFile(new File("C:\\sample.zip"));
        for (Enumeration e = zip.entries(); e.hasMoreElements(); ) {
            ZipEntry entry = (ZipEntry) e.nextElement();

            String currentEntry = entry.getName();

            if (entry.isDirectory()) {
                /*I do not know how to get the files underneath the directory
                  so that I can process them */
                InputStream is = zip.getInputStream(entry);
            } else {
                InputStream is = zip.getInputStream(entry);
            }
        }
    } catch (ZipException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Jin Kwon

Please take a look on here and here

public static void unzip(final ZipFile zipfile, final File directory)
    throws IOException {

    final Enumeration<? extends ZipEntry> entries = zipfile.entries();
    while (entries.hasMoreElements()) {
        final ZipEntry entry = entries.nextElement();
        final File file = file(directory, entry);
        if (entry.isDirectory()) {
            continue;
        }
        final InputStream input = zipfile.getInputStream(entry);
        try {
            // copy bytes from input to file
        } finally {
            input.close();
        }
    }
}

protected static File file(final File root, final ZipEntry entry)
    throws IOException {

    final File file = new File(root, entry.getName());

    File parent = file;
    if (!entry.isDirectory()) {
        final String name = entry.getName();
        final int index = name.lastIndexOf('/');
        if (index != -1) {
            parent = new File(root, name.substring(0, index));
        }
    }
    if (parent != null && !parent.isDirectory() && !parent.mkdirs()) {
        throw new IOException(
            "failed to create a directory: " + parent.getPath());
    }

    return file;
}

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edited at2021-02-1

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