Spring 引导自动配置加载失败 Spring Kafka 属性

Question

Spring 引导加载属性失败。这是我通过 yaml 文件使用的属性。

 spring:
  kafka:
    bootstrap-servers: localhost:9092
    consumer:
      auto-commit-interval: 100
      enable-auto-commit: true
      group-id: ********************
      auto-offset-reset: earliest
      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
    producer:
      batch-size: 16384
      buffer-memory: 33554432
      retries: 0
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
    listener:
      poll-timeout: 20000

我得到的异常是这个

原因：java.lang.IllegalAccessException：Class org.apache.kafka.common.utils.Utils 无法使用修饰符 [=23] 访问 class org.springframework.kafka.support.serializer.JsonDeserializer 的成员=]

我认为构造函数是受保护的。请提供一种实例化它的方法。

Answer 1

没错。参见：

protected JsonDeserializer() {
        this((Class<T>) null);
    }

    protected JsonDeserializer(ObjectMapper objectMapper) {
        this(null, objectMapper);
    }

    public JsonDeserializer(Class<T> targetType) {
        this(targetType, new ObjectMapper());
        this.objectMapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, false);
        this.objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    }

JsonDeserializer 未设计为由默认构造函数实例化，因为它需要知道 targetType 才能反序列化。

您可以将此 class 扩展到您的特定类型：

public class FooJsonDeserializer extends JsonDeserializer<Foo> { }

并已将此用作 class 值 value-deserializer 属性。

或者你可以考虑自定义DefaultKafkaConsumerFactory:

@Bean
public ConsumerFactory<?, ?> kafkaConsumerFactory(KafkaProperties properties) {
    Map<String, Object> consumerProperties = properties.buildConsumerProperties();
    consumerProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
            MyConsumerMetricsReporter.class);
    DefaultKafkaConsumerFactory<Object, Object> consumerFactory =
          new DefaultKafkaConsumerFactory<>(consumerProperties);
    consumerFactory.setValueDeserializer(new JsonDeserializer<>(Foo.class));
    return consumerFactory;
}

Spring 引导自动配置加载失败 Spring Kafka 属性

Spring Boot Auto Configuration Failed Loading Spring Kafka Properties

spring-boot

spring-kafka