我知道这个问题非常普遍,但是在采用了不同的解决方案之后,我找不到任何可行的解决方案。在Kafka中收到消息时,我想反序列化字符串以及我的自定义类对象。使用String会很好,但不能使用我的Class。我在使用者配置中添加了受信任的程序包(com.springmiddleware.entities是我的类(class)所在的程序包):

@Bean
    public Map<String, Object> consumerConfigs() {


        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "foo");
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
        props.put(JsonDeserializer.TRUSTED_PACKAGES, "com.springmiddleware.entities");

        return props;
    }

我的application.yml文件中有这个:
spring:
kafka:
    bootstrap-servers: localhost:9092
    consumer:
      group-id: foo
      auto-offset-reset: earliest
      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      properties:
        spring:
          json:
            trusted:
              packages: 'com.springmiddleware.entities'

并将这些行添加到application.properties
spring.kafka.consumer.value-deserializer=org.springframework.kafka.support.serializer.JsonDeserializer
spring.kafka.consumer.properties.spring.json.trusted.packages=com.springmiddleware.entities
spring.kafka.producer.value-serializer=org.springframework.kafka.support.serializer.JsonSerializer
spring.kafka.producer.properties.spring.json.add.type.headers=false

但是以下错误一直显示:



更新

ReceiverConfig:
@EnableKafka
@Configuration
public class ReceiverConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;

    @Bean
    public Map<String, Object> consumerConfigs() {


        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "foo");
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
        props.put(JsonDeserializer.TRUSTED_PACKAGES, "com.springmiddleware.entities");
        props.put(JsonDeserializer.USE_TYPE_INFO_HEADERS, "false");
        return props;
    }

    @Bean
    public ConsumerFactory<String, Object> consumerFactory() {
        return new DefaultKafkaConsumerFactory<>(consumerConfigs(),  new StringDeserializer(),
                new JsonDeserializer<>());
    }

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

更新2
Listener Class (Receiver):

    @KafkaListener(topics = "${app.topic.foo}")
@Service
public class Receiver {


     private CountDownLatch latch = new CountDownLatch(1);

        public CountDownLatch getLatch() {
            return latch;
        }

   @KafkaHandler
    public void listen(@Payload Crime message) {

            System.out.println("Received " + message);
    }

   @KafkaHandler
    public void listen(@Payload String message) {

        System.out.println("Received " +  message);
}

最佳答案

只需使用Overloaded JsonDeserializer构造函数



以下示例显示了如何执行此操作:

DefaultKafkaConsumerFactory<Integer, Cat1> cf = new DefaultKafkaConsumerFactory<>(props,
    new IntegerDeserializer(), new JsonDeserializer<>(Cat1.class, false));

您的代码:
@Bean
public ConsumerFactory<String, Object> consumerFactory() {
    return new DefaultKafkaConsumerFactory<>(consumerConfigs(),  new StringDeserializer(),
            new JsonDeserializer<>(Object.class,false));
}

现在在类级别使用@KafkaListener
@KafkaListener(topics = "myTopic")
@Service
public class MultiListenerBean {

@KafkaHandler
public void listen(Cat cat) {
    ...
}

@KafkaHandler
public void listen(Hat hat) {
    ...
}

@KafkaHandler(isDefault = true)
public void delete(Object obj) {
    ...
   }

}

10-04 20:54