netty服务器

@Component
   public class NettyServer {

    static final Logger log = LoggerFactory.getLogger(NettyServer.class);

    /**
     * 端口号
     */
    @Value("${webSocket.netty.port:8888}")
    int port;

    EventLoopGroup bossGroup;
    EventLoopGroup workGroup;

    @Autowired
    ProjectInitializer nettyInitializer;

    @PostConstruct
    public void start() throws InterruptedException {
        new Thread(() -> {
            bossGroup = new NioEventLoopGroup();
            workGroup = new NioEventLoopGroup();
            ServerBootstrap bootstrap = new ServerBootstrap();
            // bossGroup辅助客户端的tcp连接请求, workGroup负责与客户端之前的读写操作
            bootstrap.group(bossGroup, workGroup);
            // 设置NIO类型的channel
            bootstrap.channel(NioServerSocketChannel.class);
            // 设置监听端口
            bootstrap.localAddress(new InetSocketAddress(port));
            // 设置管道
            bootstrap.childHandler(nettyInitializer);

            // 配置完成，开始绑定server，通过调用sync同步方法阻塞直到绑定成功
            ChannelFuture channelFuture = null;
            try {
                channelFuture = bootstrap.bind().sync();
                log.info("Server started and listen on:{}", channelFuture.channel().localAddress());
                // 对关闭通道进行监听
                channelFuture.channel().closeFuture().sync();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();
    }

    /**
     * 释放资源
     */
    @PreDestroy
    public void destroy() throws InterruptedException {
        if (bossGroup != null) {
            bossGroup.shutdownGracefully().sync();
        }
        if (workGroup != null) {
            workGroup.shutdownGracefully().sync();
        }
    }
}

Netty配置

管理全局Channel以及用户对应的channel（推送消息）

  public class NettyConfig {
    
        /**
         * 定义全局单利channel组 管理所有channel
         */
        private static volatile ChannelGroup channelGroup = null;
    
        /**
         * 存放请求ID与channel的对应关系
         */
        private static volatile ConcurrentHashMap<String, Channel> channelMap = null;
    
        /**
         * 定义两把锁
         */
        private static final Object lock1 = new Object();
        private static final Object lock2 = new Object();
    
    
        public static ChannelGroup getChannelGroup() {
            if (null == channelGroup) {
                synchronized (lock1) {
                    if (null == channelGroup) {
                        channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
                    }
                }
            }
            return channelGroup;
        }
    
        public static ConcurrentHashMap<String, Channel> getChannelMap() {
            if (null == channelMap) {
                synchronized (lock2) {
                    if (null == channelMap) {
                        channelMap = new ConcurrentHashMap<>();
                    }
                }
            }
            return channelMap;
        }
    
        public static Channel getChannel(String userId) {
            if (null == channelMap) {
                return getChannelMap().get(userId);
            }
            return channelMap.get(userId);
        }
    }

管道配置

@Component
public class ProjectInitializer extends ChannelInitializer<SocketChannel> {

    /**
     * webSocket协议名
     */
    static final String WEBSOCKET_PROTOCOL = "WebSocket";

    /**
     * webSocket路径
     */
    @Value("${webSocket.netty.path:/webSocket}")
    String webSocketPath;
    @Autowired
    WebSocketHandler webSocketHandler;

    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        // 设置管道
        ChannelPipeline pipeline = socketChannel.pipeline();
        // 流水线管理通道中的处理程序（Handler），用来处理业务
        // webSocket协议本身是基于http协议的，所以这边也要使用http编解码器
        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new ObjectEncoder());
        // 以块的方式来写的处理器
        pipeline.addLast(new ChunkedWriteHandler());
        pipeline.addLast(new HttpObjectAggregator(8192));
        pipeline.addLast(new WebSocketServerProtocolHandler(webSocketPath, WEBSOCKET_PROTOCOL, true, 65536 * 10));
        // 自定义的handler，处理业务逻辑
        pipeline.addLast(webSocketHandler);
    }
}

自定义handler

 @Component
    @ChannelHandler.Sharable
    public class WebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
        private static final Logger log = LoggerFactory.getLogger(NettyServer.class);
    
        /**
         * 一旦连接，第一个被执行
         */
        @Override
        public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
            log.info("有新的客户端链接：[{}]", ctx.channel().id().asLongText());
            // 添加到channelGroup 通道组
            NettyConfig.getChannelGroup().add(ctx.channel());
        }
    
        /**
         * 读取数据
         */
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
            log.info("服务器收到消息：{}", msg.text());
    
            // 获取用户ID,关联channel
            JSONObject jsonObject = JSONUtil.parseObj(msg.text());
            String uid = jsonObject.getStr("uid");
            NettyConfig.getChannelMap().put(uid, ctx.channel());
    
            // 将用户ID作为自定义属性加入到channel中，方便随时channel中获取用户ID
            AttributeKey<String> key = AttributeKey.valueOf("userId");
            ctx.channel().attr(key).setIfAbsent(uid);
    
            // 回复消息
            ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器收到消息啦"));
        }
    
        @Override
        public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
            log.info("用户下线了:{}", ctx.channel().id().asLongText());
            // 删除通道
            NettyConfig.getChannelGroup().remove(ctx.channel());
            removeUserId(ctx);
        }
    
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            log.info("异常：{}", cause.getMessage());
            // 删除通道
            NettyConfig.getChannelGroup().remove(ctx.channel());
            removeUserId(ctx);
            ctx.close();
        }
    
        /**
         * 删除用户与channel的对应关系
         */
        private void removeUserId(ChannelHandlerContext ctx) {
            AttributeKey<String> key = AttributeKey.valueOf("userId");
            String userId = ctx.channel().attr(key).get();
            NettyConfig.getChannelMap().remove(userId);
        }
    }

推送消息接口及实现类

    public interface PushMsgService {
    
        /**
         * 推送给指定用户
         */
        void pushMsgToOne(String userId, String msg);
    
        /**
         * 推送给所有用户
         */
        void pushMsgToAll(String msg);
    
    }
    @Service
    public class PushMsgServiceImpl implements PushMsgService {
    
        @Override
        public void pushMsgToOne(String userId, String msg) {
            Channel channel = NettyConfig.getChannel(userId);
            if (Objects.isNull(channel)) {
                throw new RuntimeException("未连接socket服务器");
            }
    
            channel.writeAndFlush(new TextWebSocketFrame(msg));
        }
    
        @Override
        public void pushMsgToAll(String msg) {
            NettyConfig.getChannelGroup().writeAndFlush(new TextWebSocketFrame(msg));
        }
    }