我是否必须使用@Payload spring 注释来读取 Kafka 消息

Question

Spring for Apache Kafka 2.8.4 under https://docs.spring.io/spring-kafka/reference/html 显示了消息旁边带有 @Payload 注释的一些侦听器方法，有些则没有。例如：

@KafkaListener(id = "cat", topics = "myTopic",
          containerFactory = "kafkaManualAckListenerContainerFactory")
public void listen(String data, Acknowledgment ack) {
    ...
    ack.acknowledge();
}

和

@KafkaListener(id = "qux", topicPattern = "myTopic1")
public void listen(@Payload String foo,
        @Header(name = KafkaHeaders.RECEIVED_MESSAGE_KEY, required = false) Integer key,
        @Header(KafkaHeaders.RECEIVED_PARTITION_ID) int partition,
        @Header(KafkaHeaders.RECEIVED_TOPIC) String topic,
        @Header(KafkaHeaders.RECEIVED_TIMESTAMP) long ts
        ) {
    ...
}

哪种做法是正确的？我正在测试两者，看不出有什么不同。

Answer 1

简短的回答是否定的，您不必使用它。

长答案是“视情况而定”；如果你想对 Kafka 消息做一些验证，@Payload 会帮助你；喜欢 spring doc

中的以下内容

To configure the @KafkaListener to handle null payloads, you must use the @Payload annotation with required = false. If it is a tombstone message for a compacted log, you usually also need the key so that your application can determine which key was “deleted”. The following example shows such a configuration:

我宁愿使用普通字符串，这样您就可以通过将责任卸载到应用程序端而不是 built-in 处理的方式来避免一些已知的解析问题，例如 Poison Pill Spring.

我是否必须使用@Payload spring 注释来读取 Kafka 消息

Do I have to use @Payload spring annotation to read Kafka message

java

spring

spring-boot

apache-kafka