Question

我正在尝试使用netty创建一个多播通道，我可以通过它发送和接收多播组的消息我像这样创建了引导程序实例

channelFactory = new OioDatagramChannelFactory( workerExecutor );
bootstrap = new ConnectionlessBootstrap( channelFactory );
bootstrap.setOption( "broadcast", true );
bootstrap.setOption( "reuseAddress", true );

稍后会像这样创建频道

DatagramChannel channel;
channel = (DatagramChannel) bootstrap.bind( new InetSocketAddress( mcastPort) );
channel.joinGroup( multicastAddress );

使用此代码，我可以接收多播组的消息，但简单的channel.write();会因NPE而失败。

java.lang.NullPointerException: null address || null buffer
    at java.net.TwoStacksPlainDatagramSocketImpl.send(Native Method)
    at java.net.DatagramSocket.send(DatagramSocket.java:675)
    at org.jboss.netty.channel.socket.oio.OioDatagramWorker.write(OioDatagramWorker.java:121)
    at org.jboss.netty.channel.socket.oio.OioDatagramPipelineSink.eventSunk(OioDatagramPipelineSink.java:84)
    at *.*.*PacketHandler.writeRequested(*PacketHandler.java:72)
    at org.jboss.netty.channel.Channels.write(Channels.java:611)
    at org.jboss.netty.channel.Channels.write(Channels.java:578)
    at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:251)
    at org.jboss.netty.channel.group.DefaultChannelGroup.write(DefaultChannelGroup.java:261)

由于异常表明事件没有指定远程地址由于我不想在每个写入请求上传递多播地址，因此我调用了Channel#connect。

DatagramChannel channel;
channel = (DatagramChannel) bootstrap.bind( new InetSocketAddress( mcastPort) );
channel.joinGroup( multicastAddress );
channel.connect( new InetSocketAddress(multicastAddress, mcastPort) );

现在发送消息完美无缺，但我不再收到消息了。

我做错了什么？我正在使用netty 3.2.7.Final

修改
以下是我对netty行为的期望 它们有效还是我误解了什么？

// DatagramSocket bound to network interface "192.168.0.15" and port 12345
channel = (DatagramChannel) bootstrap.bind( new InetSocketAddress( "192.168.0.15", 12345) );
// Send IGMP Join to "239.195.255.255" in order to receive multicast packets
channel.joinGroup("239.195.255.255");

// Possibility 1
// Channels remote address gets set
channel.connect(new InetSocketAddress("239.195.255.255", 12345));
// packets gets send over interface "192.168.0.15" port 12345 to "239.195.255.255:12345"
channel.write(something);

// Possibility 2
// Send packet to explicit address
channel.write(something, new InetSocketAddress("239.195.255.255", 12345));

netty - 组播信道既可以接收也可以发送，但不能同时接收或发送

0 个答案: