<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.42.Final</version>
</dependency>

public interface ServerConst {
    String SERVICE_NAME = "netty-notice";
    int DEFAULT_PORT=9090;
}

@Slf4j
public class WebSocketChannelInitializer extends ChannelInitializer<SocketChannel> {
    private FullHttpRequestHandler paramsHandler;
    private TextWebSocketFrameHandler textHandler;
    public WebSocketChannelInitializer(FullHttpRequestHandler paramsHandler,
        TextWebSocketFrameHandler textHandler){
        this.paramsHandler=paramsHandler;
        this.textHandler=textHandler;
    }
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        log.info("連接初始化");
        //http編解碼
        ch.pipeline().addLast(new HttpServerCodec());
        //大數(shù)據(jù)量讀寫
        ch.pipeline().addLast(new ChunkedWriteHandler());
        //http消息聚合
        ch.pipeline().addLast(new HttpObjectAggregator(65536));
        //連接升級(jí)處理
        ch.pipeline().addLast(paramsHandler);
        //協(xié)議配置
        ch.pipeline().addLast(new WebSocketServerProtocolHandler("/"+ServerConst.SERVICE_NAME+"/ws"));
        //ch.pipeline().addLast(new IdleStateHandler(30, 60, 120));
        //消息處理，業(yè)務(wù)邏輯
        ch.pipeline().addLast(textHandler);
    }
}

@Slf4j
@Component
@ChannelHandler.Sharable
public class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        AttributeKey<String> utKey = AttributeKey.valueOf(UserChannelContext.USER_TOKEN);
        Attribute<String> ut = ctx.channel().attr(utKey);
        UserChannelContext.remove(ut.get(), ctx.channel());
        ctx.channel().close();
    }
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        //正常流程下不存在問(wèn)題，但是無(wú)法處理硬件層面問(wèn)題導(dǎo)致連接斷開(kāi)等,連接斷開(kāi)時(shí)移除channel
        AttributeKey<String> utKey = AttributeKey.valueOf(UserChannelContext.USER_TOKEN);
        Attribute<String> ut = ctx.channel().attr(utKey);
        UserChannelContext.remove(ut.get(),ctx.channel());
    }
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext,
        TextWebSocketFrame textWebSocketFrame) throws Exception {
        //todo 如果有長(zhǎng)耗時(shí)業(yè)務(wù)邏輯處理，建議將數(shù)據(jù)打包到另一個(gè)線程處理？
    }
}

/**
 * @Description todo 控制幀處理，關(guān)閉幀，ping幀，pong幀，暫時(shí)未處理
 * @Author 姚仲杰#80998699
 * @Date 2022/12/6 11:33
 */
public class CustomWebSocketServerProtocolHandler extends WebSocketServerProtocolHandler {
    public CustomWebSocketServerProtocolHandler(String websocketPath) {
        super(websocketPath);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, boolean checkStartsWith) {
        super(websocketPath, checkStartsWith);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols) {
        super(websocketPath, subprotocols);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols,
        boolean allowExtensions) {
        super(websocketPath, subprotocols, allowExtensions);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols,
        boolean allowExtensions, int maxFrameSize) {
        super(websocketPath, subprotocols, allowExtensions, maxFrameSize);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols,
        boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch) {
        super(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols,
        boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch,
        boolean checkStartsWith) {
        super(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch,
            checkStartsWith);
    }
    public CustomWebSocketServerProtocolHandler(String websocketPath, String subprotocols,
        boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch,
        boolean checkStartsWith,
        boolean dropPongFrames) {
        super(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch,
            checkStartsWith, dropPongFrames);
    }
    @Override
    protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out)
        throws Exception {
        super.decode(ctx, frame, out);
    }
}

@Slf4j
@Component
@ChannelHandler.Sharable
public class FullHttpRequestHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
    @Autowired
    private RedisClient redisClient;
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
        String uri = request.uri();
        log.info("連接請(qǐng)求uri：{}",uri);
        Map<CharSequence, CharSequence> queryMap = UrlBuilder.ofHttp(uri).getQuery().getQueryMap();
        String ut = (String) queryMap.get("ut");
        //todo 此處進(jìn)行認(rèn)證操作
        if (!StringUtils.isEmpty(ut)){
            UserInfo userInfo = redisClient.get(String.format(CommonCacheConst.USER_UT_KEY, ut),UserInfo.class);
            if (userInfo!=null) {
                //認(rèn)證通過(guò)將channel緩存起來(lái)，便于服務(wù)端推送消息
                //todo 推送有多少未讀消息
                //一個(gè)ut只能建立一個(gè)連接，避免連接被占滿
                if (UserChannelContext.isConnected(ut)){
                    log.info("ut={}未認(rèn)證，連接失?。。。?,ut);
                    FullHttpResponse response = new DefaultFullHttpResponse(
                        HTTP_1_1, HttpResponseStatus.FORBIDDEN, Unpooled.wrappedBuffer("多次連接".getBytes()));
                    ctx.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
                    return;
                }
                String userCode = userInfo.getUserCode();
                AttributeKey<String> userIdKey = AttributeKey.valueOf(UserChannelContext.USER_KEY);
                ctx.channel().attr(userIdKey).setIfAbsent(userCode);
                AttributeKey<String> userTokenKey = AttributeKey.valueOf(UserChannelContext.USER_TOKEN);
                ctx.channel().attr(userTokenKey).setIfAbsent(ut);
                log.info("用戶{}連接成功?。?！",userCode);
                UserChannelContext.put(userCode,ut, ctx.channel());
            }else{
                log.info("ut={}未認(rèn)證，連接失?。。?！",ut);
                FullHttpResponse response = new DefaultFullHttpResponse(
                    HTTP_1_1, HttpResponseStatus.UNAUTHORIZED, Unpooled.wrappedBuffer("未認(rèn)證".getBytes()));
                ctx.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
                return;
            }
        }else{
            log.info("連接參數(shù)不正確ut不存在");
            FullHttpResponse response = new DefaultFullHttpResponse(
                HTTP_1_1, HttpResponseStatus.BAD_REQUEST, Unpooled.wrappedBuffer("參數(shù)不正確".getBytes()));
            ctx.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
            return;
        }
        request.setUri(URLUtil.getPath(uri));
        ctx.fireChannelRead(request.retain());
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
}

public class UserChannelContext {
    public final static String USER_KEY="userCode";
    public final static String USER_TOKEN="ut";
    private static ConcurrentHashMap<String, List<Channel>> userChannelMap = new ConcurrentHashMap<>();
    private static ConcurrentHashMap<String, String> utConnectMap = new ConcurrentHashMap<>();
    public static boolean isConnected(String ut){
        return utConnectMap.containsKey(ut);
    }
    public static synchronized void put(String userCode,String ut, Channel channel) {
        utConnectMap.put(ut,ut);
        List<Channel> channels = get(userCode);
        if (channels!=null){
            channels.add(channel);
        }else{
            List<Channel> list = new ArrayList<>();
            list.add(channel);
            userChannelMap.put(userCode, list);
        }
    }
    public static List<Channel> get(String userCode) {
        return userChannelMap.get(userCode);
    }
    public static synchronized void remove(String ut,Channel channel){
        utConnectMap.remove(ut);
        AttributeKey<String> userCodeKey = AttributeKey.valueOf(USER_KEY);
        if (channel.hasAttr(userCodeKey)) {
            Attribute<String> userCode = channel.attr(userCodeKey);
            if (userCode!=null&&!StringUtils.isEmpty(userCode.get())){
                List<Channel> channels = userChannelMap.get(userCode.get());
                for (Channel cn : channels) {
                    if (cn.equals(channel)){
                        channels.remove(cn);
                        break;
                    }
                }
            }
        }
    }
}

@Component
public class NacosServiceRegister implements ApplicationContextAware, InitializingBean {
    private ApplicationContext context;
    private NacosRegistration nacosRegistration;
    @Autowired
    private NacosServiceRegistry registry;
    @Value("${netty.server.port:9090}")
    private int port;
    @Autowired
    NacosDiscoveryProperties properties;
    @Override
    public void afterPropertiesSet() throws Exception {
        NacosDiscoveryProperties nacosDiscoveryProperties = new NacosDiscoveryProperties();
        BeanUtils.copyProperties(properties, nacosDiscoveryProperties);
        nacosDiscoveryProperties.setService(ServerConst.SERVICE_NAME);
        nacosDiscoveryProperties.setPort(this.port);
        NacosRegistration nacosRegistration = new NacosRegistration(nacosDiscoveryProperties,
            context);
        this.nacosRegistration = nacosRegistration;
    }
    public void register() {
        this.registry.register(this.nacosRegistration);
    }
    public void deregister() {
        this.registry.deregister(this.nacosRegistration);
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.context = applicationContext;
    }
}

@Slf4j
@Component
public class NettyRunner implements ApplicationRunner {
    @Value("${netty.server.port:9090}")
    private int port;
    private FullHttpRequestHandler paramsHandler;
    private TextWebSocketFrameHandler textHandler;
    private EventLoopGroup bossGroup;
    private EventLoopGroup workerGroup;
    @Autowired
    NacosServiceRegister nacosServiceRegister;
    @Override
    public void run(ApplicationArguments args) throws Exception {
        this.start();
        nacosServiceRegister.register();
    }
    //養(yǎng)成好習(xí)慣，標(biāo)注下作為bean示例化的構(gòu)造函數(shù)，當(dāng)然也可以不寫
    @Autowired
    public NettyRunner(FullHttpRequestHandler paramsHandler,
        TextWebSocketFrameHandler textHandler) {
        this.paramsHandler=paramsHandler;
        this.textHandler=textHandler;
    }
    public void start() throws Exception {
        this.bossGroup = new NioEventLoopGroup(1);
        this.workerGroup = new NioEventLoopGroup();
        ServerBootstrap sb = new ServerBootstrap();
        //tcp連接隊(duì)列長(zhǎng)度
        sb.option(ChannelOption.SO_BACKLOG, 1024);
        //設(shè)置線程池，連接線程池和工作線程池
        sb.group(bossGroup,workerGroup)
            //這里怎么判斷使用epoll還是kqueue？
            .channel(NioServerSocketChannel.class)
            //服務(wù)地址于端口號(hào)設(shè)置
            .localAddress(this.port)
            //channel初始化操作
            .childHandler(new WebSocketChannelInitializer(paramsHandler,textHandler));
        sb.bind().sync();
        log.info("Netty started on port(s):{}", this.port);
    }
    @PreDestroy
    private void destroy() throws InterruptedException {
        if (ObjectUtil.isNotNull(this.bossGroup)) {
            this.bossGroup.shutdownGracefully().sync();
        }
        if (ObjectUtil.isNotNull(this.workerGroup)) {
            this.workerGroup.shutdownGracefully().sync();
        }
        nacosServiceRegister.deregister();
    }
}

public interface QueueConst {
    String NOTICE_DIRECT_QUEUE = "notice_direct_queue";
    String NOTICE_DIRECT_EXCHANGE = "notice_direct_exchange";
    String NOTICE_DIRECT_BIND_KEY = "notice_direct_bind_key";
}

@Configuration
public class QueueConfiguration {
    @Bean
    public Queue noticeQueue() {
        return new Queue(QueueConst.NOTICE_DIRECT_QUEUE);
    }
    @Bean
    public DirectExchange noticeDirectExchange() {
        return new DirectExchange(QueueConst.NOTICE_DIRECT_EXCHANGE);
    }
    @Bean
    public Binding noticeDirectBinding() {
        return BindingBuilder.bind(noticeQueue()).to(noticeDirectExchange()).with(QueueConst.NOTICE_DIRECT_BIND_KEY);
    }
}

@Component
public class NoticeReceiver {
    private static ObjectMapper MAPPER = new ObjectMapper();
    @RabbitListener(queues = QueueConst.NOTICE_DIRECT_QUEUE)
    @RabbitHandler
    public void receiveTopic(Message message) throws Exception {
        String receiveMsg = new String(message.getBody());
        message.getMessageProperties().getReceivedUserId();
        ChannelMessage channelMessage=JSONUtil.toBean(receiveMsg,ChannelMessage.class);
        //todo 將消息存庫(kù)，此處采用另一個(gè)方案，直接由消息發(fā)送方進(jìn)行存儲(chǔ)，這里只做分發(fā)
        //save
        //todo 獲取對(duì)應(yīng)用戶的channel列表,并推送消息給用戶
        List<Channel> channels = UserChannelContext.get(channelMessage.getUserId());
        for (Channel channel : channels) {
            if (channel!=null){
                //todo 發(fā)送消息
                channel.writeAndFlush(new TextWebSocketFrame(MAPPER.writeValueAsString(channelMessage.getData())));
            }
        }
        //todo 補(bǔ)充：如果用戶不在線則直接放棄;
        //todo 補(bǔ)充：無(wú)論如何消息消費(fèi)后需要返回ack
    }
    public static void main(String[] args) {
        ChannelMessage message=new ChannelMessage();
        message.setUserId("YG0000049");
        message.setData("Hello world");
        System.out.println(JSONUtil.toJsonStr(message));
    }
}

@Data
@Accessors
public class ChannelMessage<T> implements Serializable {
    private String userId;
    private T data;
}