Apache Kafka - 基于 REST API 的消费者？

Question

我跟随 this article 构建了一个简单的 Java Spring Boot 应用程序来与 Apache Kafka 一起工作。

如下所述定义生产者控制器

@RestController
@RequestMapping(value = "/kafka")
public class KafkaController {

    private final Producer producer;

    @Autowired
    KafkaController(Producer producer) {
        this.producer = producer;
    }

    @PostMapping(value = "/publish")
    public void sendMessageToKafkaTopic(@RequestParam("message") String message) {
        this.producer.sendMessage(message);
    }
}

和生产者服务如下

@Service
public class Producer {

    private static final Logger logger = LoggerFactory.getLogger(Producer.class);
    private static final String TOPIC = "users";

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    public void sendMessage(String message) {
        logger.info(String.format("#### -> Producing message -> %s", message));
        this.kafkaTemplate.send(TOPIC, message);
    }
}

如下所述的消费者服务

@Service
public class Consumer {

    private final Logger logger = LoggerFactory.getLogger(Producer.class);

    @KafkaListener(topics = "users", groupId = "group_id")
    public void consume(String message) throws IOException {
        logger.info(String.format("#### -> Consumed message -> %s", message));
    }
}

配置如下图

server:
  port: 9000
spring:
  kafka:
    consumer:
      bootstrap-servers: localhost:9092
      group-id: group_id
      auto-offset-reset: earliest
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer
    producer:
      bootstrap-servers: localhost:9092
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.apache.kafka.common.serialization.StringSerializer

它按预期工作

并在控制台上打印消息

我想要一个基于 REST API 的消费者，而不是仅仅在控制台上打印消息。我该怎么做？

Answer 1

见How to read a message from Kafka topic on demand

只需将代码（以try 开头）放入@GetMapping 方法中即可。