com.liferay.util.transport.MulticastTransport.java Source code

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Here is the source code for com.liferay.util.transport.MulticastTransport.java

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/**
 * Copyright (c) 2000-2012 Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */

package com.liferay.util.transport;

import java.io.IOException;

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>
 * The MulticastTransport will send strings across a specified multicast
 * address. It will also listen for messages and hand them to the appropriate
 * DatagramHandler.
 * </p>
 *
 * @author Michael C. Han
 */
public class MulticastTransport extends Thread implements Transport {

    public MulticastTransport(DatagramHandler handler, String host, int port) {
        super("MulticastListener-" + host + port);

        setDaemon(true);
        _handler = handler;
        _host = host;
        _port = port;
    }

    public synchronized void connect() throws IOException {
        if (_socket == null) {
            _socket = new MulticastSocket(_port);
        } else if (_socket.isConnected() && _socket.isBound()) {
            return;
        }

        _address = InetAddress.getByName(_host);

        _socket.joinGroup(_address);

        _connected = true;

        start();
    }

    public synchronized void disconnect() {

        // Interrupt all processing

        if (_address != null) {
            try {
                _socket.leaveGroup(_address);
                _address = null;
            } catch (IOException e) {
                _log.error("Unable to leave group", e);
            }
        }

        _connected = false;

        interrupt();

        _socket.close();
    }

    public synchronized void sendMessage(String msg) throws IOException {
        _outboundPacket.setData(msg.getBytes());
        _outboundPacket.setAddress(_address);
        _outboundPacket.setPort(_port);

        _socket.send(_outboundPacket);
    }

    public boolean isConnected() {
        return _connected;
    }

    @Override
    public void run() {
        try {
            while (_connected) {
                _socket.receive(_inboundPacket);
                _handler.process(_inboundPacket);
            }
        } catch (IOException e) {
            _log.error("Unable to process ", e);

            _socket.disconnect();

            _connected = false;

            _handler.errorReceived(e);
        }
    }

    private static Log _log = LogFactory.getLog(MulticastTransport.class);

    private byte[] _inboundBuffer = new byte[4096];
    private DatagramPacket _inboundPacket = new DatagramPacket(_inboundBuffer, _inboundBuffer.length);
    private byte[] _outboundBuffer = new byte[4096];
    private DatagramPacket _outboundPacket = new DatagramPacket(_outboundBuffer, _outboundBuffer.length);
    private String _host;
    private DatagramHandler _handler;
    private int _port;
    private boolean _connected;
    private MulticastSocket _socket;
    private InetAddress _address;

}