Kafka 消息序列化反序列化

主要是记录下 SpringBoot 如何集成 Kafka，完成消息队列的使用，代码包括 Json 序列化消息，生产者，消费者，配置文件。

1、maven 依赖

    org.springframework.boot
    spring-boot-starter-web


    org.springframework.kafka
    spring-kafka


    org.springframework.boot
    spring-boot-starter-json

2、定义序列化消息

public class OrderMsg{

    public String getOrderId() {
        return orderId;
    }

    public void setOrderId(String orderId) {
        this.orderId = orderId;
    }

    public String getAccountId() {
        return accountId;
    }

    public void setAccountId(String accountId) {
        this.accountId = accountId;
    }

    private String orderId;
    private String accountId;

    public OrderMsg() {}

    public OrderMsg(String orderId, String accountId) {
        this.orderId = orderId;
        this.accountId = accountId;
    }

    @Override
    public String toString() {
        return "OrderMsg{" +
                "orderId='" + orderId + ''' +
                ", accountId='" + accountId + ''' +
                '}';
    }
}

3、定义消息消费者

用于消费主题topic01，这个主题已在Kafka集群搭建的时候创建，这里直接消费；一共定义了两个消费者-consumer01和consumer02，属于orderGroup消费组，用于分担消费topic01主题3个分区里的消息。

@Component
public class OrderConsumer {

    
    @KafkaListener(id="consumer01", groupId = "orderGroup", topics = {"topic01"})
    public void processOrder1(ConsumerRecord msg) {
        System.out.println("consumer01-" +
                "topic:" + msg.topic() +
                ";partition:" + msg.partition() +
                ";key:" + msg.key() +
                ";value:" + msg.value());
    }

    @KafkaListener(id="consumer02", groupId = "orderGroup", topics = {"topic01"})
    public void processOrder2(ConsumerRecord msg) {
        System.out.println("consumer02-" +
                "topic:" + msg.topic() +
                ";partition:" + msg.partition() +
                ";key:" + msg.key() +
                ";value:" + msg.value());
    }

}

4、引入KafkaTemplate 来生产消息

@RestController
@RequestMapping("kafka")
public class OrderController {

    @Resource
    private KafkaTemplate kafkaTemplate;

@GetMapping("/order/{message}")
public void sendMessage(@PathVariable("message") String message) {
    System.out.println(message);    
    for (int i = 1; i < 10; i++) {
        kafkaTemplate.send("topic01", i+"", i+"-"+message);
    }
    kafkaTemplate.flush();
}

}

5、application.yml 配置文件

server:
  port: 8888
spring:
  kafka:
    #Kafka集群
    bootstrap-servers: 192.168.216.118:9092,192.168.216.128:9092,192.168.216.138:9092

    producer:
      acks: all
      # 重试次数
      retries: 2
      # 批量大小
      batch-size: 16384
      # 生产端缓冲区大小
      buffer-memory: 33554432
      # Kafka提供的序列化和反序列化类
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
      #开启事务
      # transaction-id-prefix: transaction-id-
      # 设置提交延时
      # 当生产端积累的消息达到batch-size或接收到消息linger.ms后,生产者就会将消息提交给kafka
      # linger.ms为0表示每接收到一条消息就交给kafka
      properties:
        enable:
          idempotence: true
        linger:
          ms: 0


    consumer:
      # 是否自动提交offset
      enable-auto-commit: true
      # 提交offset延时(接收到消息后多久提交offset)
      auto-commit-interval: 100ms
      # 当kafka中没有初始offset或offset超出范围时将自动重置offset
      # earliest:重置为分区中最小的offset;
      # latest:重置为分区中最新的offset(消费分区中新产生的数据);
      # none:只要有一个分区不存在已提交的offset,就抛出异常;
      auto-offset-reset: latest
      # 默认的消费组ID
      group-id: group01
      # 消费端key反序列化
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      # 消费端value反序列化
      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      # 批量消费每次最多消费条目数
      max-poll-records: 10
      properties:
        # 消费会话超时时间
        session:
          timeout:
            ms: 120000
        heartbeat:
          timeout:
            ms: 1000
        # 消费请求超时时间
        request:
          timeout:
            ms: 120000
        spring:
          json:
            trusted:
              packages: com.studyplan.mq.kafka.bean
        #isolation:
          #level: read_committed

    listener:
      # 关闭监听topic不存在的话项目启动报错
      missing-topics-fatal: false
      # 设置为批量消费
      # type: batch


6、浏览器输入

http://localhost:8888/kafka/order/world 进行测试，观察控制台输出。