spring-kafka

Question

我正在编写一个 spring-kafka 应用程序，其中我需要阅读 2 个主题：test1 和 test2：

public class Receiver {

    private static final Logger LOGGER = LoggerFactory
            .getLogger(Receiver.class);

    @KafkaListener(id = "bar", topicPartitions =
{ @TopicPartition(topic = "test1", partitions = { "0" }),
  @TopicPartition(topic = "test2", partitions = { "0" })})
    public void receiveMessage(String message) {
        LOGGER.info("received message='{}'", message);
    }
}

我的配置如下所示：

@Configuration
@EnableKafka
public class ReceiverConfig {

    @Value("${kafka.bootstrap.servers}")
    private String bootstrapServers;

    @Bean
    public Map<String, Object> consumerConfigs() {
        Map<String, Object> props = new HashMap<>();
        // list of host:port pairs used for establishing the initial connections
        // to the Kakfa cluster
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,
                bootstrapServers);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
                IntegerDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
                StringDeserializer.class);
        // consumer groups allow a pool of processes to divide the work of
        // consuming and processing records
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "test1");
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "test2");

        return props;
    }

    @Bean
    public ConsumerFactory<Integer, String> consumerFactory() {
        return new DefaultKafkaConsumerFactory<>(consumerConfigs());
    }

    @Bean
    public ConcurrentKafkaListenerContainerFactory<Integer, String> kafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<Integer, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());

        return factory;
    }

    @Bean
    public Receiver receiver() {
        return new Receiver();
    }
}

我需要能够只阅读来自 "test1" 的最新消息，同时能够阅读从 "test2" 最开始的所有消息。我只对应用程序启动时的 "test2" 消息感兴趣，但只要应用程序处于运行.

状态，就需要连续读取 "test1" 消息

有没有办法配置这样的功能？

Answer 1

这是一种对我有用的方法：

@KafkaListener(id = "receiver-api",         
        topicPartitions =
        { @TopicPartition(topic = "schema.topic", 
                partitionOffsets = @PartitionOffset(partition = "0", initialOffset = "0")),
                @TopicPartition(topic = "data.topic", partitions = { "0" })})
    public void receiveMessage(String message) {
        try {
                JSONObject incomingJsonObject = new JSONObject(message); 
                if(!incomingJsonObject.isNull("data")){
                    handleSchemaMessage(incomingJsonObject);
                }

                else {
                    handleDataMessage(incomingJsonObject);
                }

        } catch (Exception e) {
            e.printStackTrace();
        }

使用"partitionOffsets"注释(import org.springframework.kafka.annotation.PartitionOffset;)

是始终能够从头阅读特定主题的关键，而 "tailing" 其他主题照常阅读。

Answer 2

我也曾为这个问题苦苦挣扎，想提出一个更通用的解决方案。

虽然您的解决方案有效，但您需要对分区进行硬编码。您还可以让使用 @KafkaListener 注释的 class 实现 ConsumerSeekAware 接口。

这为您提供了三种可用于查找特定偏移量的方法。一旦分配了分区，就会调用一种方法。所以它可能看起来像这样。

@Override
public void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback) {
    assignments.keySet().stream()
        .filter(partition -> "MYTOPIC".equals(partition.topic()))
        .forEach(partition -> callback.seekToBeginning("MYTOPIC", partition.partition()));
}

这样，当您决定向主题添加更多分区时，您无需触及任何代码:)

希望这对某人有所帮助。

spring-kafka - 如何从头读一个主题，同时从头读另一个主题？

spring-kafka - how to read one topic from the beginning, while reading another one from the end?

spring-boot