ChannelListener

    public interface ChannelListener {
        void channelConnected(Channel channel);
        void channelDisconnected(Channel channel);
        void channelClosed(Channel channel);
        void channelShunned();
        void channelReconnected(Address addr);
    }

A class implementing ChannelListener can use the Channel.setChannelListener() method to register with a channel to obtain information about state changes in a channel. Whenever a channel is closed, disconnected or opened a callback will be invoked.