java - 如何在kafka springboot中从一个主题读取多种类型的json

Question

我有一个主题，我可以从中接收不同类型的 json。但是，当消费者尝试阅读消息时，我似乎遇到了异常。我尝试添加其他 bean 名称，但没有成功。看起来它正在尝试从主题中读取内容并尝试转换为从主题中读取的所有类型。有没有办法指定只应为特定输入类型启用特定工厂。有没有其他方法可以解决这个问题。

错误

Caused by: org.springframework.messaging.converter.MessageConversionException: Cannot convert from [com.lte.assessment.assessments.AssessmentAttemptRequest] to [com.lte.assessmentanalytics.data.SiteLevelAnalyticsRequest] for GenericMessage [payload=com.lte.assessment.assessments.AssessmentAttemptRequest@68eb637f, headers={kafka_offset=22, kafka_consumer=org.apache.kafka.clients.consumer.KafkaConsumer@252d8ffb, kafka_timestampType=CREATE_TIME, kafka_receivedMessageKey=null, kafka_receivedPartitionId=0, kafka_receivedTopic=ltetopic, kafka_receivedTimestamp=1546117529267}

配置

@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

@Deadpool 是对的。如果您需要更简单的解决方案，请将消息作为字符串 JSON 负载使用，并手动将它们反序列化为您的对象。

        @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;
        }

在您的监听器中，作为字符串使用。

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