Appending files to a zip file with Java

In Java 7 we got Zip File System that allows adding and changing files in zip (jar, war) without manual repackaging.

We can directly write to files inside zip files as in the following example.

Map<String, String> env = new HashMap<>(); 
env.put("create", "true");
Path path = Paths.get("test.zip");
URI uri = URI.create("jar:" + path.toUri());
try (FileSystem fs = FileSystems.newFileSystem(uri, env))
{
    Path nf = fs.getPath("new.txt");
    try (Writer writer = Files.newBufferedWriter(nf, StandardCharsets.UTF_8, StandardOpenOption.CREATE)) {
        writer.write("hello");
    }
}