SpringBoot整合Kafka

现在大多数公司都是使用SpringBoot技术，所以使用SpringBoot整合Kafka是比较重要的。接下来我们就来使用SpringBoot整合Kafka。

一、项目构建

我们首先创建一个基于maven的SpringBoot项目.

1、pom依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jihu</groupId>
    <artifactId>spring-boot-kafka</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.2.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.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>
    </dependencies>
</project>

2、application.yml配置文件

server:
  port: 8080

spring:
  kafka:
    bootstrap-servers: 192.168.131.171:9092,192.168.131.171:9093,192.168.131.171:9094
    producer: # 生产者
      retries: 3 # 设置大于0的值，则客户端会将发送失败的记录重新发送
      batch-size: 16384
      buffer-memory: 33554432
      acks: 1
      # 指定消息key和消息体的编解码方式
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.apache.kafka.common.serialization.StringSerializer
    consumer:
      group-id: default-group
      enable-auto-commit: false
      auto-offset-reset: earliest
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer
    listener:
      # 当每一条记录被消费者监听器（ListenerConsumer）处理之后提交
      # RECORD
      # 当每一批poll()的数据被消费者监听器（ListenerConsumer）处理之后提交
      # BATCH
      # 当每一批poll()的数据被消费者监听器（ListenerConsumer）处理之后，距离上次提交时间大于TIME时提交
      # TIME
      # 当每一批poll()的数据被消费者监听器（ListenerConsumer）处理之后，被处理record数量大于等于COUNT时提交
      # COUNT
      # TIME |　COUNT　有一个条件满足时提交
      # COUNT_TIME
      # 当每一批poll()的数据被消费者监听器（ListenerConsumer）处理之后, 手动调用Acknowledgment.acknowledge()后提交
      # MANUAL
      # 手动调用Acknowledgment.acknowledge()后立即提交，一般使用这种
      # MANUAL_IMMEDIATE
      ack-mode: manual_immediate

3、启动类

@SpringBootApplication
public class KafkaApplication {
    public static void main(String[] args) {
        SpringApplication.run(KafkaApplication.class);
    }
}

4、生产者代码

@RestController
public class KafkaController {
    private final static String TOPIC_NAME = "my-replicated-topic";

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    @RequestMapping("/send")
    public String send(@RequestParam("msg") String msg) {
        kafkaTemplate.send(TOPIC_NAME, "key", msg);
        return String.format("消息 %s 发送成功！", msg);
    }
}

5、消费者代码

@Component
public class MyConsumer {
    /**
     * @param record record
     * @KafkaListener(groupId = "testGroup", topicPartitions = {
     * @TopicPartition(topic = "topic1", partitions = {"0", "1"}),
     * @TopicPartition(topic = "topic2", partitions = "0",
     * partitionOffsets = @PartitionOffset(partition = "1", initialOffset = "100"))
     * },concurrency = "6")
     * //concurrency就是同组下的消费者个数，就是并发消费数，必须小于等于分区总数
     */
    @KafkaListener(topics = "my-replicated-topic", groupId = "jihuGroup")
    public void listenJihuGroup(ConsumerRecord<String, String> record, Acknowledgment ack) {
        String value = record.value();
        System.out.println("jihuGroup message: " + value);
        System.out.println("jihuGroup record: " + record);
        //手动提交offset，一般是提交一个banch，幂等性防止重复消息
        // === 每条消费完确认性能不好！
        ack.acknowledge();
    }

    //配置多个消费组
    @KafkaListener(topics = "my-replicated-topic", groupId = "jihuGroup2")
    public void listenJihuGroup2(ConsumerRecord<String, String> record, Acknowledgment ack) {
        String value = record.value();
        System.out.println("jihuGroup2 message: " + value);
        System.out.println("jihuGroup2 record: " + record);
        //手动提交offset
        ack.acknowledge();
    }
}

二、测试

编写完成后我们来启动这个SpringBoot项目。

我们在浏览器输入消息进行发送：

检查控制台，发现收到了消息，至此SpringBoot整合Kafka完成。

当然，我们还有很多更复杂的消费和发送场景，会在后面的文章更新，欢迎大家关注。