如何在kafka springboot中从一个主题中读取多种类型的json

Question

我有一个主题，从中我可以接收不同类型的JSON。然而，当使用者试图读取消息时，我似乎得到了一个异常。我尝试添加其他bean名称，但没有成功。它似乎试图从主题中阅读，并试图转换到从主题中阅读的所有类型。是否有一种方法可以指定只对特定输入类型启用特定工厂。还有其他方法可以解决这个问题吗。

@EnableKafka
@Configuration
public class KafkaConfig {
    static Map<String, Object> config = new HashMap();

    static {
        config.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "127.0.0.1:9092");
        config.put(ConsumerConfig.GROUP_ID_CONFIG, "group_id");
        config.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        config.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
    }


    @Bean
    public ConsumerFactory<String, AssessmentAttemptRequest> assessmentAttemptDetailsEntityConsumerFactory() {
        JsonDeserializer<AssessmentAttemptRequest> deserializer = new JsonDeserializer<>();
        deserializer.addTrustedPackages("com.lte.assessment.assessments");
        return new DefaultKafkaConsumerFactory(config, new StringDeserializer(), deserializer);
    }

    @Bean(name="aaKafkaListenerFactory")
    public ConcurrentKafkaListenerContainerFactory aaKafkaListenerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, AssessmentAttemptRequest> factory = new ConcurrentKafkaListenerContainerFactory();
        factory.setConsumerFactory(assessmentAttemptDetailsEntityConsumerFactory());
        return factory;
    }

    @Bean
    public ConsumerFactory<String, AssessmentQuestionAnalyticsEntity> assessmentQuestionAnalyticssEntityConsumerFactory() {
        JsonDeserializer<AssessmentQuestionAnalyticsEntity> deserializer = new JsonDeserializer<>();
        deserializer.addTrustedPackages("com.lte.assessment.assessments");
        return new DefaultKafkaConsumerFactory(config, new StringDeserializer(), deserializer);
    }

    @Bean(name="aqKafkaListenerFactory")
    public ConcurrentKafkaListenerContainerFactory aqKafkaListenerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, AssessmentQuestionAnalyticsEntity> factory = new ConcurrentKafkaListenerContainerFactory();
        factory.setConsumerFactory(assessmentQuestionAnalyticssEntityConsumerFactory());
        return factory;
    }

    @Bean
    public ConsumerFactory<String, SiteLevelAnalyticsEntity> siteLevelAnalyticsEntityConsumerFactory() {
        JsonDeserializer<SiteLevelAnalyticsEntity> deserializer = new JsonDeserializer<>();
        deserializer.addTrustedPackages("com.lte.assessment.assessments");
        return new DefaultKafkaConsumerFactory(config, new StringDeserializer(), deserializer);
    }

    @Bean("slaKafkaListenerFactory")
    public ConcurrentKafkaListenerContainerFactory slaKafkaListenerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, SiteLevelAnalyticsEntity> factory = new ConcurrentKafkaListenerContainerFactory();
        factory.setConsumerFactory(siteLevelAnalyticsEntityConsumerFactory());
        return factory;
    }
}

服务

@Service
public class TopicObserver implements
        ConsumerSeekAware.ConsumerSeekCallback,ConsumerSeekAware{

    @Autowired
    private AssessmentAttemptService assessmentAttemptService;

    @Autowired
    private AssessmentQuestionService assessmentQuestionService;

    @Autowired
    private SiteLevelAnalyticsService siteLevelAnalyticsService;

    private final ThreadLocal<ConsumerSeekCallback> seekCallBack = new ThreadLocal<>();

    @KafkaListener(topics = "ltetopic", groupId = "group_id", containerFactory = "aaKafkaListenerFactory")
    public void consumeAttemptDetails(AssessmentAttemptRequest request) {
        assessmentAttemptService.storeAttempDetails(request);
    }

    @KafkaListener(topics = "ltetopic", groupId = "group_id", containerFactory = "aqKafkaListenerFactory")
    public void setAssessmentQeustionAnalytics(AssessmentQuestionRequest request) {
        assessmentQuestionService.storeQuestionDetails(request);
    }

    @KafkaListener(topics = "ltetopic", groupId = "group_id", containerFactory = "slaKafkaListenerFactory")
    public void siteLevelAnalytics(SiteLevelAnalyticsRequest request) {
        siteLevelAnalyticsService.storeSiteLevelDetailsDetails(request);
    }
}

Answer 1

@死侍是对的。如果您需要一个更简单的解决方案，可以将消息作为字符串JSON有效负载使用，并手动将它们反序列化为对象。

        @Bean
        public ConsumerFactory<Integer, String> createConsumerFactory() {
            Map<String, Object> props = new HashMap<>();
            props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, 
              kafkaEmbedded().getBrokersAsString());
            props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);
            props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
            props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
            return new DefaultKafkaConsumerFactory<>(props);
        }

        @Bean
        public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() {
            ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
            factory.setConsumerFactory(createConsumerFactory());
            return factory;
        }

在侦听器中，作为字符串使用。

@KafkaListener(id = "foo", topics = YOUR_TOPIC)
    public void listen(String json){
    //Convert to Object here.
}