程式化建構

此功能設計用於 @KafkaListener;然而,許多使用者已要求提供關於如何以程式化方式設定非阻塞重試的資訊。以下 Spring Boot 應用程式提供如何執行此操作的範例。

@SpringBootApplication
public class Application extends RetryTopicConfigurationSupport {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    RetryTopicConfiguration retryConfig(KafkaTemplate<String, String> template) {
        return RetryTopicConfigurationBuilder.newInstance()
                .maxAttempts(4)
                .autoCreateTopicsWith(2, (short) 1)
                .create(template);
    }

    @Bean
    TaskScheduler scheduler() {
        return new ThreadPoolTaskScheduler();
    }

    @Bean
    @Order(0)
    SmartInitializingSingleton dynamicRetry(RetryTopicConfigurer configurer, RetryTopicConfiguration config,
            KafkaListenerAnnotationBeanPostProcessor<?, ?> bpp, KafkaListenerContainerFactory<?> factory,
            Listener listener, KafkaListenerEndpointRegistry registry) {

        return () -> {
            KafkaListenerEndpointRegistrar registrar = bpp.getEndpointRegistrar();
            MethodKafkaListenerEndpoint<String, String> mainEndpoint = new MethodKafkaListenerEndpoint<>();
            EndpointProcessor endpointProcessor = endpoint -> {
                // customize as needed (e.g. apply attributes to retry endpoints).
                if (!endpoint.equals(mainEndpoint)) {
                    endpoint.setConcurrency(1);
                }
                // these are required
                endpoint.setMessageHandlerMethodFactory(bpp.getMessageHandlerMethodFactory());
                endpoint.setTopics("topic");
                endpoint.setId("id");
                endpoint.setGroupId("group");
            };
            mainEndpoint.setBean(listener);
            try {
                mainEndpoint.setMethod(Listener.class.getDeclaredMethod("onMessage", ConsumerRecord.class));
            }
            catch (NoSuchMethodException | SecurityException ex) {
                throw new IllegalStateException(ex);
            }
            mainEndpoint.setConcurrency(2);
            mainEndpoint.setTopics("topic");
            mainEndpoint.setId("id");
            mainEndpoint.setGroupId("group");
            configurer.processMainAndRetryListeners(endpointProcessor, mainEndpoint, config, registrar, factory,
                    "kafkaListenerContainerFactory");
        };
    }


    @Bean
    ApplicationRunner runner(KafkaTemplate<String, String> template) {
        return args -> {
            template.send("topic", "test");
        };
    }

}

@Component
class Listener implements MessageListener<String, String> {

    @Override
    public void onMessage(ConsumerRecord<String, String> record) {
        System.out.println(KafkaUtils.format(record));
        throw new RuntimeException("test");
    }

}
主題的自動建立僅會在組態在應用程式內容重新整理之前處理時發生,如上述範例所示。若要在執行時期設定容器,則需要使用其他技術建立主題。