directories in a zip file when using java.util.zip.ZipOutputStream

Question

Lets say I have a file t.txt, a directory t and another file t/t2.txt. If I use the linux zip utility \"zip -r t.zip t.txt t\", I get a zip file with the following entries i

Answer 1

Java Program to Zip(folders contains either empty or full ones)

public class ZipUsingJavaUtil {
    /*
     * Zip function zip all files and folders
     */
    @Override
    @SuppressWarnings("finally")
    public boolean zipFiles(String srcFolder, String destZipFile) {
        boolean result = false;
        try {
            System.out.println("Program Start zipping the given files");
            /*
             * send to the zip procedure
             */
            zipFolder(srcFolder, destZipFile);
            result = true;
            System.out.println("Given files are successfully zipped");
        } catch (Exception e) {
            System.out.println("Some Errors happned during the zip process");
        } finally {
            return result;
        }
    }

    /*
     * zip the folders
     */
    private void zipFolder(String srcFolder, String destZipFile) throws Exception {
        ZipOutputStream zip = null;
        FileOutputStream fileWriter = null;
        /*
         * create the output stream to zip file result
         */
        fileWriter = new FileOutputStream(destZipFile);
        zip = new ZipOutputStream(fileWriter);
        /*
         * add the folder to the zip
         */
        addFolderToZip("", srcFolder, zip);
        /*
         * close the zip objects
         */
        zip.flush();
        zip.close();
    }

    /*
     * recursively add files to the zip files
     */
    private void addFileToZip(String path, String srcFile, ZipOutputStream zip, boolean flag) throws Exception {
        /*
         * create the file object for inputs
         */
        File folder = new File(srcFile);

        /*
         * if the folder is empty add empty folder to the Zip file
         */
        if (flag == true) {
            zip.putNextEntry(new ZipEntry(path + "/" + folder.getName() + "/"));
        } else { /*
                 * if the current name is directory, recursively traverse it
                 * to get the files
                 */
            if (folder.isDirectory()) {
                /*
                 * if folder is not empty
                 */
                addFolderToZip(path, srcFile, zip);
            } else {
                /*
                 * write the file to the output
                 */
                byte[] buf = new byte[1024];
                int len;
                FileInputStream in = new FileInputStream(srcFile);
                zip.putNextEntry(new ZipEntry(path + "/" + folder.getName()));
                while ((len = in.read(buf)) > 0) {
                    /*
                     * Write the Result
                     */
                    zip.write(buf, 0, len);
                }
            }
        }
    }

    /*
     * add folder to the zip file
     */
    private void addFolderToZip(String path, String srcFolder, ZipOutputStream zip) throws Exception {
        File folder = new File(srcFolder);

        /*
         * check the empty folder
         */
        if (folder.list().length == 0) {
            System.out.println(folder.getName());
            addFileToZip(path, srcFolder, zip, true);
        } else {
            /*
             * list the files in the folder
             */
            for (String fileName : folder.list()) {
                if (path.equals("")) {
                    addFileToZip(folder.getName(), srcFolder + "/" + fileName, zip, false);
                } else {
                    addFileToZip(path + "/" + folder.getName(), srcFolder + "/" + fileName, zip, false);
                }
            }
        }
    }
}

Answer 2

ZipOutputStream can handle empty directories by adding a forward-slash / after the folder name. Try (from)

public class Test {
    public static void main(String[] args) {
        try {
            FileOutputStream f = new FileOutputStream("test.zip");
            ZipOutputStream zip = new ZipOutputStream(new BufferedOutputStream(f));
            zip.putNextEntry(new ZipEntry("xml/"));
            zip.putNextEntry(new ZipEntry("xml/xml"));
            zip.close();
        } catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

Answer 3

You can add "/" at the end of folder name. Just use the following command:

zip.putNextEntry(new ZipEntry("xml/"));

Answer 4

String dir = "E:\Infor\Marketing\JobLog\Cloud_MomBuild_NoMirror";

public void downloadAsZip() throws IOException {
    ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream();
    ZipOutputStream zipOutputStream = new ZipOutputStream(byteOutputStream);
    Path folderPath = Paths.get(dir);
    String folderName = "Output";
    for (File file : folderPath.toFile().listFiles()) {
        String path = folderName + "/" + file.getName();
        if (file.isDirectory()) {
            writeFolderToZip(zipOutputStream, file, path);
        } else {
            writeFileToZip(zipOutputStream, file, path);
        }
    }
}

public void writeFileToZip(ZipOutputStream zipOutputStream, File file, String path) throws IOException {
    zipOutputStream.putNextEntry(new ZipEntry(path));
    FileInputStream fileInputStream = new FileInputStream(file);
    IOUtils.copy(fileInputStream, zipOutputStream);
    fileInputStream.close();
    zipOutputStream.closeEntry();
}

public void writeFolderToZip(ZipOutputStream zipOutputStream, File dir, String path) throws IOException {
    for (File file : dir.listFiles()) {
        String dirPath = path + "/" + file.getName();
        if (file.isDirectory()) {
            writeFolderToZip(zipOutputStream, file, dirPath);
        } else {
            writeFileToZip(zipOutputStream, file, dirPath);
        }
    }
}

Answer 5

Just go through the source of java.util.zip.ZipEntry. It treats a ZipEntry as directory if its name ends with "/" characters. Just suffix the directory name with "/".

Check this example for zipping just the empty directories, http://bethecoder.com/applications/tutorials/showTutorials.action?tutorialId=Java_ZipUtilities_ZipEmptyDirectory

Good luck.

Answer 6

Like others said here to add empty directory add "/" to the directory name. Pay attention NOT to add File.separator (equals to "\") which actually add an empty file to the zip.

It took me a while to understand what was my mistake - hope I save other some time...