springboot整合netty实现websocket消息推送，要求给出以下后端代码

以下是示例代码，仅供参考：

// 配置Netty服务器
@Configuration
public class NettyConfig {
    
    @Value("${netty.port}")
    private int port;
    
    @Autowired
    private WebSocketHandler webSocketHandler;
    
    @Bean
    public EventLoopGroup bossGroup() {
        return new NioEventLoopGroup();
    }
    
    @Bean
    public EventLoopGroup workerGroup() {
        return new NioEventLoopGroup();
    }
    
    @Bean
    public ServerBootstrap serverBootstrap() {
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap.group(bossGroup(), workerGroup())
                .channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, 128)
                .childOption(ChannelOption.SO_KEEPALIVE, true)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ChannelPipeline pipeline = ch.pipeline();
                        pipeline.addLast(new HttpServerCodec());
                        pipeline.addLast(new HttpObjectAggregator(65536));
                        pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
                        pipeline.addLast(webSocketHandler);
                    }
                });
        return serverBootstrap;
    }
    
    @Bean
    public ChannelFuture nettyServer() {
        return serverBootstrap().bind(port);
    }
}

// WebSocket处理器
@Component
public class WebSocketHandler extends TextWebSocketHandler {
    
    private static final Map<String, WebSocketSession> sessions = new ConcurrentHashMap<>();
    
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        sessions.put(session.getId(), session);
    }
    
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        sessions.remove(session.getId());
    }
    
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        // 处理收到的消息
    }
    
    public static void sendMessage(String sessionId, String message) throws IOException {
        WebSocketSession session = sessions.get(sessionId);
        if (session != null && session.isOpen()) {
            session.sendMessage(new TextMessage(message));
        }
    }
}