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How would an example of using a Java 7 NIO.2 multicast client look like? I could only find half of an example in the MulticastChannel documentation.

Sundae
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1 Answers1

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This example works. Note that DatagramChannel.join() requires a NetworkInterface to work.

NetworkInterface ni = NetworkInterface.getByInetAddress(address);
InetAddress group = InetAddress.getByName("239.255.0.1")

DatagramChannel dc = DatagramChannel.open(StandardProtocolFamily.INET)
    .setOption(StandardSocketOptions.SO_REUSEADDR, true)
    .bind(new InetSocketAddress(5000))
    .setOption(StandardSocketOptions.IP_MULTICAST_IF, ni);
MembershipKey key = dc.join(group, ni);

ByteBuffer byteBuffer = ByteBuffer.allocate(1500);
while (true) {
    if (key.isValid()) {
        byteBuffer.clear();
        InetSocketAddress sa = (InetSocketAddress) dc.receive(byteBuffer);
        byteBuffer.flip();

        System.out.println("Multicast received from " + sa.getHostString());

        // TODO: Parse message
    }
}
Sundae
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  • is multicast supported by of majority hardware? What if doesn't? – Ivan Voroshilin Mar 03 '14 at 13:43
  • Whether multicast works or not depends on the underlying network stack. I guess that DatagramChannel.join() should throw an exception if the system doesn't support multicast, but that may be implementation specific. – Sundae Mar 04 '14 at 14:15
  • Thanks Sundae for this minimally concise (blocking) nio example - exactly what the doctor ordered! +1 – Evgeniy Berezovsky Oct 20 '15 at 06:57