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，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，但没有奏效。似乎它试图从主题中读取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

原因： org.springframework.messaging.converter.MessageConversionException： 无法从 [com.lte.assessment.assessments.AssessmentAttemptRequest] 到 [com.lte.assessmentanalytics.data.SiteLevelAnalyticsRequest] 为 通用消息 [有效载荷=com.lte.assessment.assessments.AssessmentAttemptRequest@68eb637f， 标头={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，请将您的消息作为字符串 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 Listener 中，作为 String 使用。

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

Answer 2

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

在消费者工厂中，您分配 SiteLevelAnalyticsEntity 和 JsonDeserializer 是评估包。 请定义--deserializer.addTrustedPackages("com.lte.assessment.SiteLevelAnalyticsEntity");