1. websocket+rabbitmq实战

1.1. 前言

接到的需求是后台定向给指定web登录用户推送消息，且可能同一账号会登录多个客户端都要接收到消息

1.2. 遇坑

1、基于springboot环境搭建的websocket+rabbitmq，搭建完成后发现websocket每隔一段时间会断开，看网上有人因为nginx的连接超时机制断开，而我这似乎是因为长连接空闲时间太长而断开
2、经过测试，如果一直保持每隔段时间发送消息，那么连接不会断开，所以我采用了断开重连机制，分三种情况
1. 1.服务器正常，客户端正常且空闲时间不超过1分钟，则情况正常，超过一分钟会断线，前端发起请求重连
2. 2.服务器正常，客户端关闭或注销，服务器正常收到通知，去除对应客户端session
3. 3.服务器异常，客户端正常，客户端发现连不上服务器会尝试重连3次，3次都连不上放弃重连
3、rabbitmq定向推送，按需求需要一台机器对应一批用户，所以定制化需要服务启动的时候定向订阅该ip对应的队列名，简单说就是动态队列名的设定，所以又复杂了点，不能直接在注解写死。同时因为使用的apollo配置中心，同一集群应该相同的配置，所以也不能通过提取配置的方式设定值，为了这个点设置apollo的集群方式有点小题大做，所以采用动态读取数据库对应的ip取出对应的队列名。
4、部署线上tomcat的话，不需要加上一块代码

/**
 * 使用tomcat启动无需配置
 */
//@Configuration
//@ConditionalOnProperty(name="websocket.enabled",havingValue = "true")
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

1.3. 正式代码

1.3.1. rabbimq部分

1.application.properties配置

spring.rabbitmq.addresses = i.tzxylao.com:5672
spring.rabbitmq.username = admin
spring.rabbitmq.password = 123456
spring.rabbitmq.virtual-host = /
spring.rabbitmq.connection-timeout = 15000

交换机和队列配置

/**
 * @author laoliangliang
 * @date 2019/3/29 11:41
 */
@Configuration
@ConditionalOnProperty(name="websocket.enabled",havingValue = "true")
public class RabbitmqConfig {

    final public static String EXCHANGENAME = "websocketExchange";

    /**
     * 创建交换器
     */
    @Bean
    FanoutExchange exchange() {
        return new FanoutExchange(EXCHANGENAME);
    }

    @Bean
    public Queue queue(){
        return new Queue(orderQueueName());
    }

    @Bean
    Binding bindingExchangeMessage(Queue queue,FanoutExchange exchange) {
        return BindingBuilder.bind(queue).to(exchange);
    }

    @Bean
    public SimpleMessageListenerContainer messageListenerContainer(OrderReceiver orderReceiver, @Qualifier("rabbitConnectionFactory") CachingConnectionFactory cachingConnectionFactory){
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(cachingConnectionFactory);
        // 监听队列的名称
        container.setQueueNames(orderQueueName());
        container.setExposeListenerChannel(true);
        // 设置每个消费者获取的最大消息数量
        container.setPrefetchCount(100);
        // 消费者的个数
        container.setConcurrentConsumers(1);
        // 设置确认模式为自动确认
        container.setAcknowledgeMode(AcknowledgeMode.AUTO);
        container.setMessageListener(orderReceiver);
        return container;
    }


    /**
     * 在这里写获取订单队列名的具体过程
     * @return
     */
    public String orderQueueName(){
        return "orderChannel";
    }
}

消息监听类

/**
 * @author laoliangliang
 * @date 2019/3/29 11:38
 */
@Component
@Slf4j
@ConditionalOnProperty(name="websocket.enabled",havingValue = "true")
public class OrderReceiver implements ChannelAwareMessageListener {

    @Autowired
    private MyWebSocket myWebSocket;

    @Override
    public void onMessage(Message message, Channel channel) throws Exception {
        byte[] body = message.getBody();
        log.info("接收到消息:" + new String(body));
        try {
            myWebSocket.sendMessage(new String(body));
        } catch (IOException e) {
            log.error("send rabbitmq message error", e);
        }
    }
}

1.3.2. websocket部分

1、配置服务端点

@Configuration
@ConditionalOnProperty(name="websocket.enabled",havingValue = "true")
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

核心代码

/**
 * @author laoliangliang
 * @date 2019/3/28 14:40
 */
public abstract class AbstractWebSocket {

    protected static Map<String, CopyOnWriteArraySet<Session>> sessionStore = new HashMap<>();

    public void sendMessage(String message) throws IOException {
        List<String> userCodes = beforeSendMessage();
        for (String userCode : userCodes) {
            CopyOnWriteArraySet<Session> sessions = sessionStore.get(userCode);
            //阻塞式的(同步的)
            if (sessions !=null && sessions.size() != 0) {
                for (Session s : sessions) {
                    if (s != null) {
                        s.getBasicRemote().sendText(message);
                    }
                }
            }
        }
    }

    /**
     * 删选给谁发消息
     * @return
     */
    protected abstract List<String> beforeSendMessage();

    protected void clearSession(Session session) {
        Collection<CopyOnWriteArraySet<Session>> values = sessionStore.values();
        for (CopyOnWriteArraySet<Session> sessions : values) {
            for (Session session1 : sessions) {
                if (session.equals(session1)) {
                    sessions.remove(session);
                }
            }
        }
    }
}

@ServerEndpoint(value = "/websocket")
@Component
@ConditionalOnProperty(name="websocket.enabled",havingValue = "true")
public class MyWebSocket extends AbstractWebSocket {


    private static Logger log = LogManager.getLogger(MyWebSocket.class);

    @Autowired
    private AmqpTemplate amqpTemplate;

    @PostConstruct
    public void init() {
        /*ScheduledExecutorService executorService = Executors.newScheduledThreadPool(1);
        executorService.scheduleAtFixedRate(new Runnable() {

            int i = 0;

            @Override
            public void run() {
                amqpTemplate.convertAndSend(RabbitFanout.EXCHANGENAME, "",("msg num : " + i).getBytes());
                i++;
            }
        }, 50, 1, TimeUnit.SECONDS);*/
    }

    /**
     * 连接建立成功调用的方法
     *
     * @param session 可选的参数。session为与某个客户端的连接会话，需要通过它来给客户端发送数据
     */
    @OnOpen
    public void onOpen(Session session) throws TimeoutException {
        log.info("websocket connect");
        //10M
        session.setMaxTextMessageBufferSize(10485760);
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose(Session session) {
        clearSession(session);
    }

    /**
     * 收到客户端消息后调用的方法
     *
     * @param message 客户端发送过来的消息
     * @param session 可选的参数
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("from client request:" + message);
        CopyOnWriteArraySet<Session> sessions = sessionStore.get(message);
        if (sessions == null) {
            sessions = new CopyOnWriteArraySet<>();
        }
        sessions.add(session);
        sessionStore.put(message, sessions);
    }

    /**
     * 发生错误时调用
     *
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        clearSession(session);
    }

    /**
     * 这里返回需要给哪些用户发送消息
     * @return
     */
    @Override
    protected List<String> beforeSendMessage() {
        //TODO 给哪些用户发送消息
        return Lists.newArrayList("6");
    }
}

1.3.3. 前端代码

var websocket = null;
var reconnectCount = 0;
function connectSocket(){
    var data = basicConfig();
    if(data.websocketEnable !== "true"){
        return;
    }
    //判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
        if(data.localIp && data.localIp !== "" && data.serverPort && data.serverPort !== ""){
            websocket = new WebSocket("ws://"+data.localIp+":"+data.serverPort+data.serverContextPath+"/websocket");
        }else{
            return;
        }
    }else {
        alert('当前浏览器 不支持WebSocket')
    }

    //连接发生错误的回调方法
    websocket.onerror = function () {
        console.log("连接发生错误");
    };

    //连接成功建立的回调方法
    websocket.onopen = function () {
        reconnectCount = 0;
        console.log("连接成功");
    };

    //接收到消息的回调方法，此处添加处理接收消息方法，当前是将接收到的信息显示在网页上
    websocket.onmessage = function (event) {
        console.log("receive message：" + event.data);
    };

    //连接关闭的回调方法
    websocket.onclose = function () {
        console.log("连接关闭,如需登录请刷新页面。");
        if(reconnectCount === 3) {
            reconnectCount = 0;
            return;
        }
        connectSocket();
        basicConfig();
        reconnectCount++;
    };

    //添加事件监听
    websocket.addEventListener('open', function () {
        websocket.send(data.userCode);
    });


    //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function () {
        console.log("closeWebSocket");
    };


}

connectSocket();

function basicConfig(){
        var result = {};
        $.ajax({
            type: "post",
            async: false,
            url: "${request.contextPath}/basicConfig",
            data: {},
            success: function (data) {
                result = data;
            }
        });
        return result;
    }

1.3.4. 后端提供接口

@ApolloConfig
    private Config config;

    @RequestMapping(value = {"/basicConfig"})
    @ResponseBody
    public Map<String, Object> getUserCode(HttpSession session) {
        Map<String, Object> map = new HashMap<>(2);
        map.put("userCode",String.valueOf(session.getAttribute("userCode")));
        String websocketEnable = config.getProperty("websocket.enabled", "false");
        String serverContextPath  = config.getProperty("server.context-path", "");
        map.put("websocketEnable", websocketEnable);
        map.put("serverContextPath", serverContextPath);

        String localIp = config.getProperty("local.ip", "");
        String serverPort = config.getProperty("server.port", "80");

        map.put("localIp", localIp);
        map.put("serverPort", serverPort);
        return map;
    }

文章来源：https://www.cnblogs.com/sky-chen/p/10636964.html

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