How to encode a Map<String,String> as Base64 string?

Question

i like to encode a java map of strings as a single base 64 encoded string. The encoded string will be transmitted to a remote endpoint and maybe manipulated by a not nice person. So the worst thing that should happen are invaild key,value-tuples, but should not bring any other security risks aside.

Example:

Map<String,String> map = ...
String encoded = Base64.encode(map);

// somewhere else
Map<String,String> map = Base64.decode(encoded);

Yes, must be Base64. Not like that or that or any other of these. Is there an existing lightweight solution (Single Utils-Class prefered) out there? Or do i have to create my own?

Anything better than this?

// marshalling
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(map);
oos.close();
String encoded = new String(Base64.encodeBase64(baos.toByteArray()));

// unmarshalling 
byte[] decoded = Base64.decodeBase64(encoded.getBytes());
ByteArrayInputStream bais = new ByteArrayInputStream(decoded);
ObjectInputStream ois = new ObjectInputStream(bais);
map = (Map<String,String>) ois.readObject();
ois.close();

Thanks,

Answer 1

my primary requirements are: encoded string should be as short as possible and contain only latin characters or characters from the base64 alphabet (not my call). there are no other reqs.

Use Google Gson to convert Map to JSON. Use GZIPOutputStream to compress the JSON string. Use Apache Commons Codec Base64 or Base64OutputStream to encode the compressed bytes to a Base64 string.

Kickoff example:

public static void main(String[] args) throws IOException {
    Map<String, String> map = new HashMap<String, String>();
    map.put("key1", "value1");
    map.put("key2", "value2");
    map.put("key3", "value3");

    String serialized = serialize(map);
    Map<String, String> deserialized = deserialize(serialized, new TypeToken<Map<String, String>>() {}.getType());

    System.out.println(deserialized);
}

public static String serialize(Object object) throws IOException {
    ByteArrayOutputStream byteaOut = new ByteArrayOutputStream();
    GZIPOutputStream gzipOut = null;
    try {
        gzipOut = new GZIPOutputStream(new Base64OutputStream(byteaOut));
        gzipOut.write(new Gson().toJson(object).getBytes("UTF-8"));
    } finally {
        if (gzipOut != null) try { gzipOut.close(); } catch (IOException logOrIgnore) {}
    }
    return new String(byteaOut.toByteArray());
}

public static <T> T deserialize(String string, Type type) throws IOException {
    ByteArrayOutputStream byteaOut = new ByteArrayOutputStream();
    GZIPInputStream gzipIn = null;
    try {
        gzipIn = new GZIPInputStream(new Base64InputStream(new ByteArrayInputStream(string.getBytes("UTF-8"))));
        for (int data; (data = gzipIn.read()) > -1;) {
            byteaOut.write(data);
        }
    } finally {
        if (gzipIn != null) try { gzipIn.close(); } catch (IOException logOrIgnore) {}
    }
    return new Gson().fromJson(new String(byteaOut.toByteArray()), type);
}