首先,需要确定你的Axon框架中已经集成了Kafka,如果没有集成,可以按照Axon框架提供的文档进行集成。
在Axon框架中定义Kafka订阅器,以便将事件发布到Kafka主题中。可以使用下面的代码示例:
@Configuration public class KafkaAutoConfiguration {
private final EventBus eventBus;
public KafkaAutoConfiguration(EventBus eventBus) {
this.eventBus = eventBus;
}
@Bean
public KafkaMessageSource kafkaMessageSource(KafkaProperties kafkaProperties) {
return new KafkaMessageSource<>(consumerFactory(kafkaProperties), new NoOpDeserializer<>(),
kafkaProperties.getTopic());
}
@Bean
public ConcurrentKafkaListenerContainerFactory kafkaListenerContainerFactory(
KafkaProperties kafkaProperties) {
ConcurrentKafkaListenerContainerFactory factory =
new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory(kafkaProperties));
return factory;
}
private ConsumerFactory consumerFactory(KafkaProperties kafkaProperties) {
Map props = new HashMap<>(kafkaProperties.buildConsumerProperties());
return new DefaultKafkaConsumerFactory<>(props, new StringDeserializer(),
new StringDeserializer());
}
@Bean
public KafkaTopicProvisioner kafkaTopicProvisioner(TopicManager topicManager) {
return new KafkaTopicProvisioner(topicManager, KafkaTopicConfig.builder()
.withPostCreateAction(this::subscribeHandlers)
.build());
}
private void subscribeHandlers(String s) {
AnnotationEventHandlerAdapter.subscribe(new KafkaHandlerAdapter(eventBus), s);
}
}
@KafkaListener(topics = "${axon.kafka.topic}") public class SampleEventHandler {
private final Logger logger = LoggerFactory.getLogger(getClass());
@Autowired
private ObjectMapper objectMapper;
@EventHandler
public void on(String eventData) throws JsonProcessingException {
logger.debug("Received event from Kafka: {}", eventData);
// Deserialize the event json string
ScrumEvent event = objectMapper.readValue(eventData, ScrumEvent.class);
// Handle the event
// ...
}
}
这个事件处理器使用Spring Kafka的@KafkaListener注解来订阅指定的Kafka主题。一旦事件消息从Kafka主题中被接收到,它们将被反序列化