jodd-core/src/main/java/jodd/io/ZipUtil.java
public static File zlib(final File file) throws IOException {
		if (file.isDirectory()) {
			throw new IOException("Can't zlib folder");
		}
		FileInputStream fis = new FileInputStream(file);
		Deflater deflater = new Deflater(Deflater.BEST_COMPRESSION);

		String zlibFileName = file.getAbsolutePath() + ZLIB_EXT;

		DeflaterOutputStream dos = new DeflaterOutputStream(new FileOutputStream(zlibFileName), deflater);

		try {
			StreamUtil.copy(fis, dos);
		} finally {
			StreamUtil.close(dos);
			StreamUtil.close(fis);
		}

		return new File(zlibFileName);
	}
public static File zlib(final File file) throws IOException {
		if (file.isDirectory()) {
			throw new IOException("Can't zlib folder");
		}
		FileInputStream fis = new FileInputStream(file);
		Deflater deflater = new Deflater(Deflater.BEST_COMPRESSION);

		String zlibFileName = file.getAbsolutePath() + ZLIB_EXT;

		DeflaterOutputStream dos = new DeflaterOutputStream(new FileOutputStream(zlibFileName), deflater);

		try {
			StreamUtil.copy(fis, dos);
		} finally {
			StreamUtil.close(dos);
			StreamUtil.close(fis);
		}

		return new File(zlibFileName);
	}
Compresses a file into zlib archive.