将 Spring Bean 装配进生产者/消费者拦截器

Doubao 中英对照 Wiring Spring Beans into Producer/Consumer Interceptors

Apache Kafka 提供了向生产者和消费者添加拦截器的机制。这些对象由 Kafka 而非 Spring 管理，因此常规的 Spring 依赖注入无法用于装配所依赖的 Spring Bean。不过，你可以使用拦截器的 config() 方法手动装配这些依赖。以下 Spring Boot 应用展示了如何通过覆盖 Spring Boot 的默认工厂，将某个依赖 bean 添加到配置属性中来做到这一点。

@SpringBootApplication
public class Application {

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

    @Bean
    public ConsumerFactory<?, ?> kafkaConsumerFactory(SomeBean someBean) {
        Map<String, Object> consumerProperties = new HashMap<>();
        // consumerProperties.put(..., ...)
        // ...
        consumerProperties.put(ConsumerConfig.INTERCEPTOR_CLASSES_CONFIG, MyConsumerInterceptor.class.getName());
        consumerProperties.put("some.bean", someBean);
        return new DefaultKafkaConsumerFactory<>(consumerProperties);
    }

    @Bean
    public ProducerFactory<?, ?> kafkaProducerFactory(SomeBean someBean) {
        Map<String, Object> producerProperties = new HashMap<>();
        // producerProperties.put(..., ...)
        // ...
        producerProperties.put(ProducerConfig.INTERCEPTOR_CLASSES_CONFIG, MyProducerInterceptor.class.getName());
        producerProperties.put("some.bean", someBean);
        return new DefaultKafkaProducerFactory<>(producerProperties);
    }

    @Bean
    public SomeBean someBean() {
        return new SomeBean();
    }

    @KafkaListener(id = "kgk897", topics = "kgh897")
    public void listen(String in) {
        System.out.println("Received " + in);
    }

    @Bean
    public ApplicationRunner runner(KafkaTemplate<String, String> template) {
        return args -> template.send("kgh897", "test");
    }

    @Bean
    public NewTopic kRequests() {
        return TopicBuilder.name("kgh897")
            .partitions(1)
            .replicas(1)
            .build();
    }

}

public class SomeBean {

    public void someMethod(String what) {
        System.out.println(what + " in my foo bean");
    }

}

public class MyProducerInterceptor implements ProducerInterceptor<String, String> {

    private SomeBean bean;

    @Override
    public void configure(Map<String, ?> configs) {
        this.bean = (SomeBean) configs.get("some.bean");
    }

    @Override
    public ProducerRecord<String, String> onSend(ProducerRecord<String, String> record) {
        this.bean.someMethod("producer interceptor");
        return record;
    }

    @Override
    public void onAcknowledgement(RecordMetadata metadata, Exception exception) {
    }

    @Override
    public void close() {
    }

}

public class MyConsumerInterceptor implements ConsumerInterceptor<String, String> {

    private SomeBean bean;

    @Override
    public void configure(Map<String, ?> configs) {
        this.bean = (SomeBean) configs.get("some.bean");
    }

    @Override
    public ConsumerRecords<String, String> onConsume(ConsumerRecords<String, String> records) {
        this.bean.someMethod("consumer interceptor");
        return records;
    }

    @Override
    public void onCommit(Map<TopicPartition, OffsetAndMetadata> offsets) {
    }

    @Override
    public void close() {
    }

}

结果：

producer interceptor in my foo bean
consumer interceptor in my foo bean
Received test