How to convert from JSON to Inet4Address in Java - incidentally, this is the only way to create an InetAddress object for a host that is not DNS-resolvable (see in the example, how it sets both hostname and IP for an arbitrary server).

JsonSerialize.java

package com.alertavert.samples;

import com.fasterxml.jackson.databind.ObjectMapper;

import java.net.Inet4Address;

/**
 * Simple example to show how to create a Java @link{InetAddress} from a JSON representation.
 *
 * <p>Jackson will try to use the @link{Inet4Address#Inet4Address(String, int)} constructor, and it
 * will fail if the JSON tries to pass instead an array of four bytes; in other words this
 * <strong>will fail</strong>:
 *
 * <pre>{
 *     "hostName": "mordor",
 *     "address": [192, 168, 1, 50]
 * }</pre>
 *
 * <p>The four octets must instead be first converted to a four-byte @code{int} and then passed
 * in like thus:
 *
 * <pre>{
 *     "hostName": "mordor",
 *     "address": -1062731470
 * }</pre>
 *
 * @author marco
 *
 */
public class JsonSerialize {

    static int fromByteArray(int[] ipv4) {
        int result = 0;
        for (int i = 0; i < 4; ++i) {
            result += (ipv4[i] & 0xFF) << (8 * (3 - i));
        }
        return result;
    }

    static String ipToString(byte[] ip) {
        StringBuilder sb = new StringBuilder();
        for (byte b : ip) {
            sb.append(b & 0xFF).append('.');
        }
        sb.setLength(sb.length() - 1);
        return sb.toString();
    }

    public static void main(String[] args) {
        ObjectMapper mapper = new ObjectMapper();
        int address = fromByteArray(new int[]{192, 168, 1, 50});

        System.out.println("The address is: " + address);
        String json = "{\"hostName\": \"mordor\", \"address\": " + address + "}";
        try {
            Inet4Address ip = mapper.readValue(json, Inet4Address.class);
            System.out.println("Host: " + ip.getHostName());
            System.out.print("IP: " + ipToString(ip.getAddress()));
        } catch (Exception  e) {
            System.err.println("The JSON could not be converted: " + e.getLocalizedMessage());
            System.exit(1);
        }
    }
}

Nice... it looks like this is for IP4 only?