How to access MessageHeaders in Kafka batch listener - spring-boot

Question

I have the below Autoconfiguration class for Kafka:
#Configuration
#EnableKafka
#ConditionalOnClass(KafkaReceiver.class)
#ConditionalOnProperty({"spring.kafka.bootstrap-servers"})
public class KafkaAutoConfiguration<T> { #Value("${spring.kafka.bootstrap-servers}")
private String bootstrapServers;
private KafkaProperties kafkaConfig;
private String groupId;
#Autowired
public void setKafkaProperties(KafkaProperties properties) {
this.kafkaConfig = properties;
}
#Bean
public Map<String, Object> consumerConfigs() {
Map<String, Object> props = new HashMap<>();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,
bootstrapServers);
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
org.apache.kafka.common.serialization.ByteArrayDeserializer.class);
props.put(ConsumerConfig.GROUP_ID_CONFIG, kafkaConfig.getGroupId());
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
return props;
}
#Bean
public ConsumerFactory<String, String> consumerFactory() {
return new DefaultKafkaConsumerFactory<>(consumerConfigs());
}
#Bean
public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() {
ConcurrentKafkaListenerContainerFactory<String, String> factory =
new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory());
return factory;
}
#Bean
public ConcurrentKafkaListenerContainerFactory<String, String> kafkaBatchListenerContainerFactory() {
ConcurrentKafkaListenerContainerFactory<String, String> factory =
new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory());
factory.setBatchListener(true);
return factory;
}
#Bean
public DefaultKafkaHeaderMapper headerMapper(){
return new DefaultKafkaHeaderMapper();
}
#Bean("simpleReceiver")
#ConditionalOnMissingBean(name = "simpleReceiver")
#ConditionalOnProperty({"service.kafka.consumer.topics"})
public KafkaReceiver simpleReceiver() {
return new KafkaSimpleReceiver();
}
#Bean("batchReceiver")
#ConditionalOnMissingBean(name = "batchReceiver")
#ConditionalOnProperty({"service.kafka.consumer.batch-topics"})
public KafkaReceiver batchReceiver() {
return new KafkaBatchReceiver();
}
}
Simple listener bean:
public class KafkaSimpleReceiver implements KafkaReceiver {
#KafkaListener(topics = "#{'${service.kafka.consumer.topics}'.split(',')}", containerFactory = "kafkaListenerContainerFactory")
public void receive(ConsumerRecord record, #Headers MessageHeaders headers) throws KafkaException {
}
}
Batch listener bean:
public class KafkaBatchReceiver implements KafkaReceiver {
#KafkaListener(topics = "#{'${service.kafka.consumer.batch-topics}'.split(',')}", containerFactory = "kafkaBatchListenerContainerFactory")
public void receive(List<ConsumerRecord> records, #Headers MessageHeaders headers) throws KafkaException {
}
}
Simple listener is working fine, but I am getting the following error for batch listener. How can we access MessageHeaders in this case?
A parameter of type 'List<ConsumerRecord>' must be the only parameter (except for an optional 'Acknowledgment' and/or 'Consumer')
EDIT
This is what I did to convert ConsumerRecord to MessageHeaders
public void receive(List<ConsumerRecord> records) {
for(ConsumerRecord record : records) {
Map<String, Object> headersList = new HashMap<>();
for(final Header h : record.headers()) {
headersList.put(h.key(), new String(h.value()));
}
MessageHeaders headers = new MessageHeaders(headersList);
}
}

Answer 1

You can get a list of Message<?>.
#KafkaListener(topics = "so54086076", id = "so54086076")
public void listen(List<Message<?>> records) {
System.out.println(records.size() + ":" + records);
}
The message payloads will be the ConsumerRecord.value(); the other ConsumerRecord properties will be in the headers.