Server

public class Server {
    public static final int INET_PORT = 8888;
    public static void main(String[] args) throws Exception {
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        try {
            serverBootstrap.group(boss, worker)
                    .channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ServerChannelInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(INET_PORT).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

public class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(5, 10, 8, TimeUnit.SECONDS));
        pipeline.addLast(new ServerChannelHandler());
    }
}

public class ServerChannelHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            String eventMsg = StringUtil.EMPTY_STRING;
            switch (event.state()) {
                case READER_IDLE:
                    eventMsg = "读空闲";
                    break;
                case WRITER_IDLE:
                    eventMsg = "写空闲";
                    break;
                case ALL_IDLE:
                    eventMsg = "读写空闲";
                    break;
            }

            System.out.println(ctx.channel().remoteAddress() + "," + eventMsg);
        }
    }
}

Client

public class MyChatClient {
    public static void main(String[] args) throws Exception{
        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        try {
            bootstrap.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new MyChatClientInitializer());
            Channel channel = bootstrap.connect("localhost", 8888).sync().channel();

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

            for (; ; ) {
                channel.writeAndFlush(br.readLine() + "\r\n");
            }

        } finally {
            group.shutdownGracefully();
        }
    }
}

public class MyChatClientInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyChatClientlHandler());
    }
}

public class MyChatClientlHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }
}