server端

public class Server {
    public static void main(String[] args) throws Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup(); // 负责处理来自客户端的链接
        EventLoopGroup workerGroup = new NioEventLoopGroup();//负责处理任务
        ServerBootstrap bootstrap = new ServerBootstrap();//配置类
        bootstrap.group(bossGroup,workerGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new ServerHandler());//添加处理器
                    }
                })
                .option(ChannelOption.SO_BACKLOG, 128)
                .childOption(ChannelOption.SO_KEEPALIVE, true);
        ChannelFuture future = bootstrap.bind(8888).sync();
        future.channel().closeFuture().sync();//阻塞线程
        workerGroup.shutdownGracefully();
        bossGroup.shutdownGracefully();
    }
}

ServerHandler

/**
     * 收到数据时调用
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try{
            InetSocketAddress address = (InetSocketAddress)ctx.channel().remoteAddress();
            System.out.println(address.getPort());
            System.out.println(address.getAddress());
            //doing else something
            ByteBuf buf = (ByteBuf) msg;
            String result = convertByteBufToString(buf);
            System.out.println("收到客户端的信息:"+result);
            System.out.println("开始响应");
            //给客户端响应完成之后，关闭该客户端连接
            ctx.writeAndFlush(Unpooled.copiedBuffer(result.getBytes())).addListener(ChannelFutureListener.CLOSE);
            System.out.println("响应结束");
        }finally {
            ReferenceCountUtil.release(msg);
        }
    }
    /**
     * 抛出异常时调用
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
    /**
     *  将buf转为string
     * @param buf
     * @return
     */
    public String convertByteBufToString(ByteBuf buf) {
        String str;
        if (buf.hasArray()) { // 处理堆缓冲区
            str = new String(buf.array(), buf.arrayOffset() + buf.readerIndex(), buf.readableBytes());
        } else { // 处理直接缓冲区以及复合缓冲区
            byte[] bytes = new byte[buf.readableBytes()];
            buf.getBytes(buf.readerIndex(), bytes);
            str = new String(bytes, 0, buf.readableBytes());
        }
        return str;
    }

客户端

public class Client {
    public static void main(String[] args) throws Exception{
        EventLoopGroup workerGroup = new NioEventLoopGroup();//负责处理任务
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(workerGroup)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new ClientHandler());
                    }
                })
                .option(ChannelOption.SO_BACKLOG, 128)
                .option(ChannelOption.SO_KEEPALIVE, true);
        ChannelFuture f = bootstrap.connect("127.0.0.1",8888);
        f.channel().writeAndFlush(Unpooled.copiedBuffer("中国".getBytes()));
        f.channel().closeFuture().sync();
        workerGroup.shutdownGracefully();
    }
}

客户端handler

public class ClientHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            ByteBuf buf = (ByteBuf)msg;
            String response = convertByteBufToString(buf);
            System.out.println("收到的响应为:"+response);
        }finally {
            ReferenceCountUtil.release(msg);
        }
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
    public String convertByteBufToString(ByteBuf buf) {
        String str;
        if (buf.hasArray()) { // 处理堆缓冲区
            str = new String(buf.array(), buf.arrayOffset() + buf.readerIndex(), buf.readableBytes());
        } else { // 处理直接缓冲区以及复合缓冲区
            byte[] bytes = new byte[buf.readableBytes()];
            buf.getBytes(buf.readerIndex(), bytes);
            str = new String(bytes, 0, buf.readableBytes());
        }
        return str;
    }
}