spring boot 集成kafka

1.在pom.xml文件上添加依赖

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.3.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.5</version>
    </dependency>
</dependencies>

2.配置文件application.properties

# kafka
spring.kafka.bootstrap-servers=192.168.3.146:8092
spring.kafka.consumer.group-id=springboot-group1
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer
logging.level.root=info 

3.添加消费类和发送消息类

@Component
public class KafkaReceiver {
    @KafkaListener(topics = {"wftest"})
    public void listen(ConsumerRecord<?, ?> record) {
        Optional<?> kafkaMessage = Optional.ofNullable(record.value());
        if (kafkaMessage.isPresent()) {
            Object message = kafkaMessage.get();
            System.out.println("record =" + record);
            System.out.println("message =" + message);
        }
    }
}

@Component
public class KafkaSender {

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    private Gson gson = new GsonBuilder().create();

    public void send() {
        Message message = new Message();
        message.setId(System.currentTimeMillis());
        message.setMsg(UUID.randomUUID().toString());
        message.setSendTime(new Date());
        kafkaTemplate.send("wftest", gson.toJson(message));
    }
}

public class Message {
    private Long id;

    private String msg;

    private Date sendTime;


    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public Date getSendTime() {
        return sendTime;
    }

    public void setSendTime(Date sendTime) {
        this.sendTime = sendTime;
    }

4.测试

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        ConfigurableApplicationContext context =  SpringApplication.run(Application.class, args);

        KafkaSender sender = context.getBean(KafkaSender.class);
        for (int i = 0; i < 3; i++) {
            sender.send();

            try {
                Thread.sleep(3_000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

运行时报错：org.apache.kafka.common.errors.TimeoutException。

排查问题：

1.kafka中间件是否正常启动

2.配置文件配置是否有有问题

3.hosts配置文件是否配置kafka服务器的hostname

我们可以打开debug日志，查看详细日志信息。

logging.level.root=debug

如图所示：我们可以通过日志可以分析出来，它使用的是hostname连接kafka服务器的，所以要配置hosts文件。