寻求组播的异步通信方法(MulticastChannel)!!!
// join multicast group on this interface, and also use this
// interface for outgoing multicast datagrams
NetworkInterface ni = NetworkInterface.getByName("hme0");
DatagramChannel dc = DatagramChannel.open(StandardProtocolFamily.INET)
.setOption(StandardSocketOptions.SO_REUSEADDR, true)
.bind(new InetSocketAddress(5000))
.setOption(StandardSocketOptions.IP_MULTICAST_IF, ni);
InetAddress group = InetAddress.getByName("225.4.5.6");
MembershipKey key = dc.join(group, ni);