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

		String gzipName = file.getAbsolutePath() + GZIP_EXT;

		GZIPOutputStream gzos = new GZIPOutputStream(new FileOutputStream(gzipName));
		try {
			StreamUtil.copy(fis, gzos);
		} finally {
			StreamUtil.close(gzos);
			StreamUtil.close(fis);
		}

		return new File(gzipName);
	}
public static File gzip(final File file) throws IOException {
		if (file.isDirectory()) {
			throw new IOException("Can't gzip folder");
		}
		FileInputStream fis = new FileInputStream(file);

		String gzipName = file.getAbsolutePath() + GZIP_EXT;

		GZIPOutputStream gzos = new GZIPOutputStream(new FileOutputStream(gzipName));
		try {
			StreamUtil.copy(fis, gzos);
		} finally {
			StreamUtil.close(gzos);
			StreamUtil.close(fis);
		}

		return new File(gzipName);
	}
Compresses a file into gzip archive.