服务端

public class Server {
    private final int port;

    public Server(int port) {
        this.port = port;
    }

    public void run() {
        //创建两个事件循环组，bossGroup只处理连接请求，workGroup处理客户端业务处理，交给bossGroup
        //两个都是无线循环
        //默认CPU核*2
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            //创建服务端启动对象，配置参数
            ServerBootstrap bootstrap = new ServerBootstrap();

            //用链式编程进行设置
            bootstrap.group(bossGroup, workGroup)//设置两个线程组
                    .channel(NioServerSocketChannel.class)//使用NioSocketChannel作为服务器通道实现
                    .option(ChannelOption.SO_BACKLOG, 128)//设置线程队列个数
                    .childOption(ChannelOption.SO_KEEPALIVE, true)//设置保持活动连接状态
                    .childHandler(new ServerInitializer());//给workGroup的EventLoop对应的管道设置处理器

            System.out.println("服务器启动");

            //启动服务器，绑定端口，生成ChannelFuture对象
            ChannelFuture future = bootstrap.bind(port).sync();

            //给ChannelFuture注册监听器，监控关心的事件
            future.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture channelFuture) throws Exception {
                    if (future.isSuccess()) {
                        System.out.println("监听端口成功");
                    } else {
                        System.out.println("监听端口失败");
                    }
                }
            });

            //对关闭通道进行监听(非阻塞监听，异步模型)
            future.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new Server(666).run();
    }
}

服务端Initializer类

public class ServerInitializer extends ChannelInitializer<SocketChannel> {
    //给pipeline设置处理器
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        channel.pipeline()
                .addLast("decoder",new StringDecoder())//解码器
                .addLast("encoder",new StringEncoder())//编码器
                .addLast("ServerHandler", new ServerHandler());//添加自定义Handler
    }
}

服务端Handler类

//SimpleChannelInboundHandler继承HandlerAdapter
// 客户端与服务端相互通讯数据封装成String
public class ServerHandler extends SimpleChannelInboundHandler<String> {
    //定义一个Channel组，管理所有Channel
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    SimpleDateFormat date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    //建立连接，触发此事件
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        //获取当前channel
        Channel channel = ctx.channel();
        //将加入信息推送给其他客户端。该方法会将channelGroup中所有channel遍历并发送
        channelGroup.writeAndFlush(Unpooled.copiedBuffer(date.format(new Date()) + channel.remoteAddress() + " 加入聊天", CharsetUtil.UTF_8));
        //将当前channel加入到channelGroup
        channelGroup.add(channel);
    }

    //断开连接，触发此事件，将离开信息推送给在线客户
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        //将当前channel加入到channelGroup
        Channel channel = ctx.channel();
        //将加入信息推送给其他客户端。该方法会将channelGroup中所有channel遍历并发送
        channelGroup.writeAndFlush(Unpooled.copiedBuffer(date.format(new Date()) + channel.remoteAddress() + " 离开聊天", CharsetUtil.UTF_8));
    }

    //当通道活动时，触发此事件
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println(date.format(new Date()) + " " + ctx.channel().remoteAddress() + " 上线了");
    }

    //当通道不活动，触发此事件
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println(date.format(new Date()) + " " + ctx.channel().remoteAddress() + " 离线了");
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        //获取当前channel
        Channel channel = ctx.channel();
        //遍历channelGroup
        channelGroup.forEach(ch -> {
            //判断不是当前channel，转发消息
            if (channel != ch) {
                ch.writeAndFlush(Unpooled.copiedBuffer(date.format(new Date()) + channel.remoteAddress() + "：" + msg, CharsetUtil.UTF_8));
            } else {
                //ch.writeAndFlush(Unpooled.copiedBuffer(date.format(new Date()) + channel.remoteAddress() + "：" + msg, CharsetUtil.UTF_8));
            }
        });
    }

    //处理异常，关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

客户端

public class Client {
    private final String host;
    private final int port;

    public Client(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void run() {
        //客户端只需要一个事件循环组
        EventLoopGroup group = new NioEventLoopGroup();

        try {
            //创建客户端启动对象，配置参数
            Bootstrap bootstrap = new Bootstrap();

            //用链式编程进行设置
            bootstrap.group(group)//设置事件循环组
                    .channel(NioSocketChannel.class)//设置客户端通道实现
                    .handler(new ClientInitializer());//给workGroup的EventLoop对应的管道设置处理器

            //启动客户端，绑定端口，连接服务端
            ChannelFuture future = bootstrap.connect(host, port).sync();

            //得到channel
            Channel channel = future.channel();
            System.out.println("----------" + channel.localAddress() + "---------");
            //客户端需要输入信息，创建扫描器
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNextLine()) {
                String msg = scanner.nextLine();
                channel.writeAndFlush(Unpooled.copiedBuffer(msg, CharsetUtil.UTF_8));
            }
            //对关闭通道进行监听(非阻塞监听，异步模型)
            future.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new Client("127.0.0.1", 666).run();
    }
}

客户端Initializer类

public class ClientInitializer extends ChannelInitializer<SocketChannel> {
    //给pipeline设置处理器
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        channel.pipeline()
                .addLast("decoder",new StringDecoder())//解码器
                .addLast("encoder",new StringEncoder())//编码器
                .addLast("ClientHandler", new ClientHandler());//添加自定义Handler
    }
}

客户端Handler类

//SimpleChannelInboundHandler继承HandlerAdapter
// 客户端与服务端相互通讯数据封装成String
public class ClientHandler extends SimpleChannelInboundHandler<String> {
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }

    //处理异常，关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}