十.SpringBoot集成Kafka

首先看一下整体项目代码结构:

image.png

首先看一下pom.xml的内容:

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.1.4.RELEASE
         
    
    com.travelsky
    swagger_mysql_redis_kafka_demo
    0.0.1-SNAPSHOT
    swagger_mysql_redis_kafka_demo
    Demo project for Spring Boot

    
        1.8
    

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

        
            org.springframework.boot
            spring-boot-starter-test
            test
        

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            1.3.0
        

        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        

        
            mysql
            mysql-connector-java
            5.1.46
        

        
            org.springframework.boot
            spring-boot-starter-data-redis
        

        
            com.alibaba
            fastjson
            1.2.47
        

        
        
            org.springframework.kafka
            spring-kafka
            2.2.6.RELEASE
        

    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            

            
                org.mybatis.generator
                mybatis-generator-maven-plugin
                1.3.7
                
                    
                        mysql
                        mysql-connector-java
                        5.1.21
                    
                    
                        org.mybatis.generator
                        mybatis-generator-core
                        1.3.7
                    
                
                
                    
                        Generate MyBatis Artifacts
                        package
                        
                            generate
                        
                    
                
                
                    
                    true
                    
                    true
                    
                    src/main/resources/generatorConfig.xml
                
            
        
    

我的springboot版本2.14，跟kafka整个jar包只有一个,我用低版本jar包都报错，这个没问题

        
            org.springframework.kafka
            spring-kafka
            2.2.6.RELEASE
        

首先定义一个bean用来发送消息的载体：

public class UserLog {
    private String username;
    private String userid;
    private String state;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getUserid() {
        return userid;
    }

    public void setUserid(String userid) {
        this.userid = userid;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    @Override
    public String toString() {
        return "UserLog{" +
                "username='" + username + '\'' +
                ", userid='" + userid + '\'' +
                ", state='" + state + '\'' +
                '}';
    }
}

定义消息的发送者:

import com.alibaba.fastjson.JSON;
import com.travelsky.swagger_mysql_redis_kafka_demo.domain.UserLog;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Component;

@Component
public class UserLogProducer {
    @Autowired
    KafkaTemplate kafkaTemplate;

    public void sendLog(String userid){
        UserLog userLog = new UserLog();
        userLog.setUsername("jhp");
        userLog.setUserid(userid);
        userLog.setState("0");
        System.err.println("发送用户日志数据:"+userLog);
        kafkaTemplate.send("test_kafka", JSON.toJSONString(userLog));
    }
}

消息的发送直接使用KafkaTemplate模板即可,都封装好了,直接使用

再看消息的消费者:

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

import java.util.Optional;

@Component
public class UserLogConsumer {
    @KafkaListener(topics = {"test_kafka"})
    public void consumer(ConsumerRecord consumerRecord){
        //判断是否为null
        Optional kafkaMessage = Optional.ofNullable(consumerRecord.value());

        if(kafkaMessage.isPresent()){
            //得到Optional实例中的值
            Object message = kafkaMessage.get();
            System.err.println("消费消息:"+message);
        }
    }
}

消费机制是通过监听器实现的,直接使用这个@KafkaListener(topics = {"test_kafka"})注解接口,它可以根据指定的条件进行消息的监听

写一个启动应用类:

@GetMapping("/kafka")
    public void testKafka(){
        for (int i = 0; i < 10; i++) {
            userLogProducer.sendLog(String.valueOf(i));
        }
    }

再看一下对应的配置文件:

#============== kafka ===================
#172.24.112.13:9092,172.24.112.14:9092,172.24.112.15:9092
spring.kafka.bootstrap-servers=172.24.112.13:9092,172.24.112.14:9092,172.24.112.15:9092
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.consumer.group-id=test-consumer-group
spring.kafka.consumer.enable-auto-commit=true
spring.kafka.consumer.auto-commit-interval=1000
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer

这个时候观察控制台打印的消息:

微信截图_20190514172841.png