springboot集成kafka

1. 导入spring-kafka依赖信息

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<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- kafkfa -->
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.apache.kafka</groupId>
                <artifactId>kafka-clients</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
    </dependency>
</dependencies>

2. 在resources下创建文件application.yml

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server:
  port: 9991
spring:
  application:
    name: kafka-demo
  kafka:
    bootstrap-servers: 192.168.200.130:9092
    producer:
      retries: 10
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.apache.kafka.common.serialization.StringSerializer
    consumer:
      group-id: ${spring.application.name}-test
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer

3. 消息生产者

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@RestController
public class HelloController {

    @Autowired
    private KafkaTemplate<String,String> kafkaTemplate;

    @GetMapping("/hello")
    public String hello(){
        kafkaTemplate.send("wzh-topic","hello-kafka");
        return "ok";
    }
}

4. 消息消费者

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@Component
public class HelloListener {

    @KafkaListener(topics = "wzh-topic")
    public void onMessage(String message){
        if(!StringUtils.isEmpty(message)){
            System.out.println(message);
        }
    }
}

传递消息为对象
目前springboot整合后的kafka，因为序列化器是StringSerializer，这个时候如果需要传递对象可以有两种方式

方式一：可以自定义序列化器，对象类型众多，这种方式通用性不强。

方式二：可以把要传递的对象进行转json字符串，接收消息后再转为对象即可。

步骤

1. 发送消息

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@GetMapping("/hello")
public String hello(){
    User user = new User();
    user.setUsername("xiaowang");
    user.setAge(18);
    kafkaTemplate.send("user-topic", JSON.toJSONString(user));
    return "ok";
}

2. 接收消息

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@Component
public class HelloListener {

    @KafkaListener(topics = "user-topic")
    public void onMessage(String message){
        if(!StringUtils.isEmpty(message)){
            User user = JSON.parseObject(message, User.class);
            System.out.println(user);
        }
    }
}