Spring Boot 4 and Kafka share consumer

1.java

@Configuration
public class ShareConsumerConfig {

    @Bean
    public ShareConsumerFactory<String, String> shareConsumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
                  StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
                  StringDeserializer.class);
        return new DefaultShareConsumerFactory<>(props);
    }

    @Bean
    public ShareKafkaListenerContainerFactory<String, String>
            shareKafkaListenerContainerFactory(
                ShareConsumerFactory<String, String> shareConsumerFactory) {
        return new ShareKafkaListenerContainerFactory<>(shareConsumerFactory);
    }
}

2.java

@KafkaListener(
    topics = "image-processing",
    groupId = "image-processors",
    containerFactory = "shareKafkaListenerContainerFactory"
)
public void processImage(String imageUrl) {
    // Process the image
    imageService.process(imageUrl);
    // Implicit ACCEPT when method completes successfully
}

3.java

@Bean
public ShareKafkaListenerContainerFactory<String, String>
        shareKafkaListenerContainerFactory(
            ShareConsumerFactory<String, String> shareConsumerFactory) {
    ShareKafkaListenerContainerFactory<String, String> factory =
        new ShareKafkaListenerContainerFactory<>(shareConsumerFactory);
    factory.setConcurrency(10); // 10 concurrent consumer threads
    return factory;
}