AnnounceGroupChannel.java 文件源码

private synchronized DatagramChannel getChannel() throws IOException {
    if (channel == null || !channel.isOpen()) {
        if (shutdown.get()) {
            throw new IllegalStateException("Channel has been shut down");
        }
        ProtocolFamily protocolFamily = InternetProtocolUtils.getProtocolFamily(group.getAddress().getAddress());
        DatagramChannel _channel = selector.provider().openDatagramChannel(protocolFamily);
        _channel.setOption(StandardSocketOptions.SO_REUSEADDR, true);
        // bind to any-local before setting TTL
        int port = group.getAddress().getPort();
        if (protocolFamily == StandardProtocolFamily.INET) {
            _channel.bind(new InetSocketAddress(Inet4Address.getByName("0.0.0.0"), port));
        } else {
            _channel.bind(new InetSocketAddress(Inet6Address.getByName("[::]"), port));
        }
        int timeToLive = group.getTimeToLive();
        if (timeToLive != 1) {
            _channel.setOption(StandardSocketOptions.IP_MULTICAST_TTL, timeToLive);
        }

        for (NetworkInterface iface : networkInterfaces) {
            _channel.join(group.getAddress().getAddress(), iface);
        }

        _channel.configureBlocking(false);
        channel = _channel;
    }
    return channel;
}