A Generic UDP Listener that can be configured to listen to UDP messages on any port and pass the messages to a MessageHandler<T> instance for processing .The default packet bufferSize can be overridden by using the constructor that takes a bufferSize argument.

GenericUdpListener.java

package com.yourcompany.util;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.util.concurrent.Executor;

public class GenericUdpListener implements Runnable
{
    private static final int       ZERO       = 0;
    private int                    port;
    private int                    bufferSize = 65536; // default buffer size = 2^16
    private Executor               executor;
    private MessageHandler<byte[]> messageHandler;

    public GenericUdpListener(int port, Executor executor, MessageHandler<byte[]> messageHandler)
    {
        this.port = port;
        this.executor = executor;
        this.messageHandler = messageHandler;
    }

    protected GenericUdpListener(int port, int bufferSize, Executor executor,
        MessageHandler<byte[]> messageHandler)
    {
        this(port, executor, messageHandler);
        this.bufferSize = bufferSize;
    }

    @Override
    public void run()
    {
        DatagramSocket socket = null;
        try
        {
            socket = new DatagramSocket(port);
            byte[] buffer = new byte[bufferSize];
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
            LogUtil.LOG.info(String.format("Listening on Port: %s", port));
            while (true)
            {
                socket.receive(packet);
                final byte[] receivedBytes = new byte[packet.getLength()];
                System.arraycopy(packet.getData(), ZERO, receivedBytes, ZERO, receivedBytes.length);
                executor.execute(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        messageHandler.handleMessage(receivedBytes);
                    }
                });
            }
        }
        catch (Exception e)
        {
            LOG.error("", e);
        }
        finally
        {
            if (socket != null)
            {
                try
                {
                    socket.close();
                }
                catch (Exception e)
                {
                    LOG.error("", e);
                }
            }
        }
    }
}

MessageHandler.java

package com.yourcompany.util;

public interface MessageHandler<T>
{
    void handleMessage(T message);
}