SpringBoot整合RocketMQ遇到的坑怎么解决

本篇内容主要讲解“SpringBoot整合RocketMQ遇到的坑怎么解决”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“springBoot整合RocketMQ遇到的坑怎么解决”吧!

应用场景

在实现RocketMQ消费时，一般会用到@RocketMQMessageListener注解定义Group、Topic以及selectorExpression（数据过滤、选择的规则）为了能支持动态筛选数据，一般都会使用表达式，然后通过apollo或者cloud config进行动态切换。

引入依赖

 <!-- RocketMq Spring Boot Starter--> <dependency>  <groupId>org.apache.rocketmq</groupId>  <artifactId>rocketmq-spring-boot-starter</artifactId>  <version>2.0.4</version>  </dependency>

消费者代码

@RocketMQMessageListener(consumerGroup = "${rocketmq.group}",topic ="${rocketmq.topic}",selectorExpression = "${rocketmq.selectorExpression}")public class Consumer implements RocketMQListener<String> {    @Override    public void onMessage(String s) {        System.out.println("消费到的数据为："+s);    }}

问题排查

RocketMQMessageListener整个注解默认selectorExpression为*，表示接收当前Topic下的所有数据，如果我们想对tags进行动态配置，在使用${rocketmq.selectorExpression}表达式时会发现所有数据全被过滤了，跟踪源码（ListenerContainerConfiguration.java）发现在创建listener时selectorExpression的数据在通environment环境变量中获取对应的数据后又被覆盖了，导致整个过滤条件被变更为表达式。

@Override    public void afterSingletonsInstantiated() {    // 获取所有所有使用了RocketMQMessageListener注解的bean        Map<String, Object> beans = this.applicationContext.getBeansWithAnnotation(RocketMQMessageListener.class);        if (Objects.nonNull(beans)) {        // 循环注册容器            beans.forEach(this::reGISterContainer);        }    }    private void registerContainer(String beanName, Object bean) {        Class<?> clazz = aopProxyUtils.ultimateTargetClass(bean);// 校验当前bean是否实现了RocketMQListener接口        if (!RocketMQListener.class.isAssignableFrom(bean.getClass())) {            throw new IllegalStateException(clazz + " is not instance of " + RocketMQListener.class.getName());        }// 获取bean上的annotation        RocketMQMessageListener annotation = clazz.getAnnotation(RocketMQMessageListener.class);// 解析group及topic，可支持表达式        String consumerGroup = this.environment.resolvePlaceholders(annotation.consumerGroup());        String topic = this.environment.resolvePlaceholders(annotation.topic());        boolean listenerEnabled =            (boolean)rocketMQProperties.getConsumer().getListeners().getOrDefault(consumerGroup, Collections.EMPTY_MAP)                .getOrDefault(topic, true);        if (!listenerEnabled) {            log.debug(                "Consumer Listener (group:{},topic:{}) is not enabled by configuration, will ignore initialization.",                consumerGroup, topic);            return;        }        validate(annotation);        String containerBeanName = String.fORMat("%s_%s", DefaultRocketMQListenerContainer.class.getName(),            counter.incrementAndGet());        GenericApplicationContext genericApplicationContext = (GenericApplicationContext)applicationContext;// 注册bean的，调用createRocketMQListenerContainer        genericApplicationContext.registerBean(containerBeanName, DefaultRocketMQListenerContainer.class,            () -> createRocketMQListenerContainer(containerBeanName, bean, annotation));        DefaultRocketMQListenerContainer container = genericApplicationContext.getBean(containerBeanName,            DefaultRocketMQListenerContainer.class);        if (!container.isRunning()) {            try {                container.start();            } catch (Exception e) {                log.error("Started container failed. {}", container, e);                throw new RuntimeException(e);            }        }        log.info("Register the listener to container, listenerBeanName:{}, containerBeanName:{}", beanName, containerBeanName);    }    private DefaultRocketMQListenerContainer createRocketMQListenerContainer(String name, Object bean,        RocketMQMessageListener annotation) {        DefaultRocketMQListenerContainer container = new DefaultRocketMQListenerContainer();                container.setRocketMQMessageListener(annotation);                String nameServer = environment.resolvePlaceholders(annotation.nameServer());        nameServer = StringUtils.isEmpty(nameServer) ? rocketMQProperties.getNameServer() : nameServer;        String accessChannel = environment.resolvePlaceholders(annotation.accessChannel());        container.setNameServer(nameServer);        if (!StringUtils.isEmpty(accessChannel)) {            container.setAccessChannel(AccessChannel.valueOf(accessChannel));        }        container.setTopic(environment.resolvePlaceholders(annotation.topic()));        // 此处已经根据表达式将数据取出        String tags = environment.resolvePlaceholders(annotation.selectorExpression());        if (!StringUtils.isEmpty(tags)) {            container.setSelectorExpression(tags);        }        container.setConsumerGroup(environment.resolvePlaceholders(annotation.consumerGroup()));        // 此处将SelectorExpression的数据覆盖成了表达式        container.setRocketMQMessageListener(annotation);        container.setRocketMQListener((RocketMQListener)bean);        container.setObjectMapper(objectMapper);        container.setMessageConverter(rocketMQMessageConverter.getMessageConverter());        container.setName(name);  // REVIEW ME, use the same clientId or multiple?        return container;    }

问题解决

因为ListenerContainerConfiguration类是实现了SmartInitializingSingleton接口的afterSingletonsInstantiated方法，我们可以通过反射对selectorExpression的数据在ListenerContainerConfiguration进行初始化前进行解析并赋值回去。

@Configurationpublic class ChangeSelectorExpressionBeforeMQInit implements InitializingBean {    @Autowired    private ApplicationContext applicationContext;    @Autowired    private StandardEnvironment environment;    @Override    public void afterPropertiesSet() throws Exception {        Map<String,Object> beans =applicationContext.getBeansWithAnnotation(RocketMQMessageListener.class);        for (Object bean : beans.values()){            Class<?> clazz = AopProxyUtils.ultimateTargetClass(bean);            if (!RocketMQListener.class.isAssignableFrom(bean.getClass())) {                continue;            }            RocketMQMessageListener annotation = clazz.getAnnotation(RocketMQMessageListener.class);            InvocationHandler invocationHandler = Proxy.getInvocationHandler(annotation);            Field field = invocationHandler.getClass().getDeclaredField("memberValues");            field.setAccessible(true);            Map<String, Object> memberValues = (Map<String, Object>) field.get(invocationHandler);            for (Map.Entry<String,Object> entry: memberValues.entrySet()) {                if(Objects.nonNull(entry)){                    memberValues.put(entry.geTKEy(),environment.resolvePlaceholders(String.valueOf(entry.getValue())));                }            }        }    }}

初次之外，在2.1.0版本的依赖包中已经修复了此Bug，在不造成依赖冲突的前提下，建议使用2.1.0以上的版本包。

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