kafka（五）spring-kafka（2）详解与demo

w_t_y_y2024-06-26 22:19

一、简单的收发消息demo

父工程pom：

<?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.example</groupId>
    <artifactId>kafka-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <modules>
        <module>producer</module>
        <module>consumer-1</module>
        <module>consumer-2</module>
    </modules>

    <!-- springBoot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
    </parent>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--kafka-->
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
<!--            <version>3.0.0</version>-->
        </dependency>

        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>

        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.78</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>
1、生产者
1.1、配置文件
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer

user.topic = userTest
school.topic = schoolTest
1.2、dto
package com.example.dto;

import lombok.Builder;
import lombok.Data;

@Data
@Builder
public class SchoolDTO {
    private String schoolId;
    private String schoolName;
}

package com.example.dto;

import lombok.Builder;
import lombok.Data;

@Data
@Builder
public class UserDTO {
    private String userId;
    private String userName;
    private Integer age;
}
1.3、service
package com.example.service.impl;

import com.alibaba.fastjson.JSON;
import com.example.dto.SchoolDTO;
import com.example.dto.UserDTO;
import com.example.service.SchoolService;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;

@Service("schoolService")
@Slf4j
public class SchoolServiceImpl implements SchoolService {

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    @Value("${school.topic}")
    private String schoolTopic;

    @Override
    public void sendSchoolMsg(SchoolDTO schoolDTO) {
        String msg = JSON.toJSONString(schoolDTO);
        ProducerRecord producerRecord = new ProducerRecord(schoolTopic,msg);
        kafkaTemplate.send(producerRecord);
        log.info("school消息发送成功");
    }
}

package com.example.service.impl;

import com.alibaba.fastjson.JSON;
import com.example.dto.UserDTO;
import com.example.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;


@Service("userService")
@Slf4j
public class UserServiceImpl implements UserService {

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    @Value("${user.topic}")
    private String userTopic;

    @Override
    public void sendUserMsg(UserDTO userDTO) {
        String msg = JSON.toJSONString(userDTO);
        ProducerRecord producerRecord = new ProducerRecord(userTopic,msg);
        kafkaTemplate.send(producerRecord);
        log.info("user消息发送成功");
    }
}
1.4、启动类
package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ProducerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ProducerApplication.class, args);
    }
}
2、消费者
2.1、配置文件
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.auto-offset-reset=earliest
spring.kafka.consumer.enable-auto-commit = true 


user.topic = userTest
user.group.id = user-group-1

school.topic = schoolTest
school.group.id = school-group-1

server.port = 2222
2.2、监听
package com.example.listen;

import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.kafka.support.Acknowledgment;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Optional;
import java.util.Properties;

@Component
@Slf4j
public class SchoolConsumer {

    @KafkaListener(topics = "${school.topic}", groupId = "${school.group.id}")
    public void consumer(ConsumerRecord<?, ?> record) {
        try {
            Object message = record.value();
            if (message != null) {
                String msg = String.valueOf(message);
                log.info("接收到:msg={},topic:{},partition={},offset={}",msg,record.topic(),record.partition(),record.offset());

            }
        } catch (Exception e) {
            log.error("topic:{},is consumed error:{}", record.topic(), e.getMessage());
        } finally {
            //ack.acknowledge();
        }
    }
}

package com.example.listen;

import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class UserConsumer {

    @KafkaListener(topics = "${user.topic}", groupId = "${user.group.id}")
    public void consumer(ConsumerRecord<?, ?> record) {
        try {
            Object message = record.value();
            if (message != null) {
                String msg = String.valueOf(message);
                log.info("接收到:msg={},topic:{},partition={},offset={}",msg,record.topic(),record.partition(),record.offset());

            }
        } catch (Exception e) {
            log.error("topic:{},is consumed error:{}", record.topic(), e.getMessage());
        } finally {
            //ack.acknowledge();
        }
    }
}

不指定group.id会报错，这也验证了kafka consumer必须要有group id。如写：

复制代码 
@KafkaListener(topics = "${user.topic}")
public void consumer(ConsumerRecord<?, ?> record) 启动报错：

Caused by: java.lang.IllegalStateException: No group.id found in consumer config, container properties, or @KafkaListener annotation; a group.id is required when group management is used.

at org.springframework.util.Assert.state(Assert.java:73) ~[spring-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]

2.3、启动类
package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.EnableKafka;

@SpringBootApplication
//@EnableKafka
public class Consumer1Application {
    public static void main(String[] args) {
        SpringApplication.run(Consumer1Application.class, args);
    }
}
3、测试

启动消费者：

生产者这里通过单元测试来发送消息：

package com.demo.kafka;

import com.example.ProducerApplication;
import com.example.dto.SchoolDTO;
import com.example.dto.UserDTO;
import com.example.service.SchoolService;
import com.example.service.UserService;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@SpringBootTest(classes = {ProducerApplication.class}, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@RunWith(SpringRunner.class)
public class Test {

    @Autowired
    private SchoolService schoolService;

    @Autowired
    private UserService userService;

    @org.junit.Test
    public void sendUserMsg(){
        UserDTO userDTO = UserDTO.builder()
                .userId("id-1")
                .age(18)
                .userName("zs")
                .build();
        userService.sendUserMsg(userDTO);
    }

    @org.junit.Test
    public void sendSchoolMsg(){
        SchoolDTO schoolDTO = SchoolDTO.builder()
                .schoolId("schoolId-1")
                .schoolName("mid school")
                .build();
        schoolService.sendSchoolMsg(schoolDTO);
    }

}

运行单测，观察消费者输出：

修改参数再次运行，观察到消费者都可以正常监听：

2024-06-22 17:09:06.383  INFO 76104 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 2222 (http) with context path ''
2024-06-22 17:09:06.390  INFO 76104 --- [ntainer#1-0-C-1] org.apache.kafka.clients.Metadata        : Cluster ID: ZdpIAHTjS9GhJlvPP8n0Rw
2024-06-22 17:09:06.392  INFO 76104 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Discovered group coordinator localhost:9092 (id: 2147483647 rack: null)
2024-06-22 17:09:06.393  INFO 76104 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.ConsumerCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Revoking previously assigned partitions []
2024-06-22 17:09:06.394  INFO 76104 --- [ntainer#1-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : partitions revoked: []
2024-06-22 17:09:06.394  INFO 76104 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] (Re-)joining group
2024-06-22 17:09:06.401  INFO 76104 --- [ntainer#0-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-2, groupId=school-group-1] Successfully joined group with generation 11
2024-06-22 17:09:06.403  INFO 76104 --- [ntainer#0-0-C-1] o.a.k.c.c.internals.ConsumerCoordinator  : [Consumer clientId=consumer-2, groupId=school-group-1] Setting newly assigned partitions [schoolTest-0]
2024-06-22 17:09:06.403  INFO 76104 --- [           main] com.example.Consumer1Application         : Started Consumer1Application in 8.606 seconds (JVM running for 9.621)
2024-06-22 17:09:06.413  INFO 76104 --- [ntainer#0-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : partitions assigned: [schoolTest-0]
2024-06-22 17:09:06.491  INFO 76104 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Successfully joined group with generation 3
2024-06-22 17:09:06.493  INFO 76104 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.ConsumerCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Setting newly assigned partitions [userTest-0]
2024-06-22 17:09:06.611  INFO 76104 --- [ntainer#1-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : partitions assigned: [userTest-0]
2024-06-22 17:16:29.775  INFO 76104 --- [ntainer#1-0-C-1] com.example.listen.UserConsumer          : 接收到:msg={"age":18,"userId":"id-1","userName":"zs"},topic:userTest,partition=0,offset=4
2024-06-22 17:16:48.157  INFO 76104 --- [ntainer#0-0-C-1] com.example.listen.SchoolConsumer        : 接收到:msg={"schoolId":"schoolId-1","schoolName":"mid school"},topic:schoolTest,partition=0,offset=1
2024-06-22 17:17:39.458  INFO 76104 --- [ntainer#1-0-C-1] com.example.listen.UserConsumer          : 接收到:msg={"age":20,"userId":"id-2","userName":"ls"},topic:userTest,partition=0,offset=5
2024-06-22 17:17:59.474  INFO 76104 --- [ntainer#0-0-C-1] com.example.listen.SchoolConsumer        : 接收到:msg={"schoolId":"schoolId-2","schoolName":"primary school"},topic:schoolTest,partition=0,offset=2
4、多个消费者
4.1、同一个groupId

将consumer-1的代码copy到consumer-2，注意端口号修改成不一样的3333，并启动，

spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.auto-offset-reset=earliest
spring.kafka.consumer.enable-auto-commit = true 


user.topic = userTest
user.group.id = user-group-1

school.topic = schoolTest
school.group.id = school-group-1

server.port = 3333

2024-06-22 17:23:59.524  INFO 78096 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 3333 (http) with context path ''
2024-06-22 17:23:59.531  INFO 78096 --- [           main] example.Consumer2Application             : Started Consumer2Application in 7.534 seconds (JVM running for 8.506)
2024-06-22 17:24:00.021  INFO 78096 --- [ntainer#0-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-2, groupId=school-group-1] Successfully joined group with generation 12
2024-06-22 17:24:00.024  INFO 78096 --- [ntainer#0-0-C-1] o.a.k.c.c.internals.ConsumerCoordinator  : [Consumer clientId=consumer-2, groupId=school-group-1] Setting newly assigned partitions []
2024-06-22 17:24:00.025  INFO 78096 --- [ntainer#0-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : partitions assigned: []
2024-06-22 17:24:00.028  INFO 78096 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.AbstractCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Successfully joined group with generation 4
2024-06-22 17:24:00.028  INFO 78096 --- [ntainer#1-0-C-1] o.a.k.c.c.internals.ConsumerCoordinator  : [Consumer clientId=consumer-4, groupId=user-group-1] Setting newly assigned partitions []
2024-06-22 17:24:00.029  INFO 78096 --- [ntainer#1-0-C-1] o.s.k.l.KafkaMessageListenerContainer    : partitions assigned: []

再执行次生产者的Test，观察两个消费者：

可以看到consumer-1接收到了，而consumer-2没有接收到。

再次执行，结果相同。school也是同样的结果。

验证了：同一个topic下的某个分区只能被消费者组中的一个消费者消费。

4.2、不同group

现修改cosumer-2中groupId并重启

user.group.id = user-group-2
school.group.id = school-group-2

启动后自动接收了之前发送的所有消息（因为这是一个新的消费者组，且配置文件指定了earliest）：

再次发送新的消息：

可以看到consumer-1和2同时都接收到了：

验证了：同一个topic可以被不同的消费者组消费。

二、消费者分配策略

上面当conusmer-1和consumer-2使用同一个groupId，并且只有一个partition时，始终只有consumer-1能接收到消息，另外一个consumer-2接收不到消息。这是消费者的分配策略决定的，消费者有4种分配策略

1、RangeAssignor （默认）

即上面未指定的情况。

2、RoundRobinAssignor ：
#消费者分配策略
spring.kafka.consumer.properties.partition.assignment.strategy=org.apache.kafka.clients.consumer.RoundRobinAssignor
3、StickyAssignor （粘性）：
spring.kafka.consumer.properties.partition.assignment.strategy=org.apache.kafka.clients.consumer.StickyAssignor

下面将两个consumer的配置文件（除了端口号）都改成一样的：

spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.auto-offset-reset=earliest
spring.kafka.consumer.enable-auto-commit = true 
#消费者分配策略
spring.kafka.consumer.properties.partition.assignment.strategy=org.apache.kafka.clients.consumer.RoundRobinAssignor


user.topic = userTest
user.group.id = user-group-1

school.topic = schoolTest
school.group.id = school-group-1

结合下面的生产者分区一块来看下

三、生产者分区partition

上面只有一个patition， 所以两个topic各自只有一个数据目录，看下数据文件：

1、修改topic分区数量

注意：

partition需要在创建topic时设置，如果不设置，默认分区数量为1，如我直接修改发送的代码

会报错：

org.apache.kafka.common.KafkaException: Invalid partition given with record: 1 is not in the range [0...1).

这里需要为已经存在的topic增加分区，方法有两种。命令修改（可视化界面修改）或者java代码修改，修改后消费者也需要重启，否则接收不到新分区的消息，从启动日志也能看到每个consumer分配的topic-partition，如我先启动consumer-2再启动的consumer-1：

1.1、执行kafka命令或者在kafka可视化平台修改

这里我是执行命令修改的：修改为3个partition

D:\javas\kafka\kafka_2.12-3.5.2\bin\windows>
kafka-topics.bat --bootstrap-server localhost:9092 --alter --topic userTest--partitions 3

执行后可以看到多了几个数据文件

1.2、java代码方法修改
import org.apache.kafka.clients.admin.AdminClient;
import org.apache.kafka.clients.admin.AdminClientConfig;
import org.apache.kafka.clients.admin.NewTopic;
import org.apache.kafka.common.KafkaFuture;
 
import java.util.Collections;
import java.util.Properties;
import java.util.concurrent.ExecutionException;
 
public class KafkaTopicUpdater {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Properties config = new Properties();
        config.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
 
        AdminClient adminClient = AdminClient.create(config);
 
        NewTopic newTopic = new NewTopic("test", 3, (short) 1);
 
        KafkaFuture<Void> future = adminClient.createTopics(Collections.singleton(newTopic)).all();
 
        future.get();
 
        adminClient.close();
    }
}
2、分区方法

（以下消费者结果，消费者的分配策略均为StickyAssignor ）。

生产者代码，将之前使用的

ProducerRecord(String topic, V value)

改为：

ProducerRecord(String topic, Integer partition, K key, V value)：
2.1、指定分区

当发送时指定了partition就使用该partition。

ProducerRecord producerRecord = new ProducerRecord(userTopic,1,null,msg);

消费者：

consumer-2接收到了，consumer-1没有收到消息

将partirion修改为0

ProducerRecord producerRecord = new ProducerRecord(userTopic,0,null,msg);

consumer-1接收到，consumer-2没有接收到

**2.2、**轮询

partition=null && key=null

ProducerRecord producerRecord = new ProducerRecord(userTopic,null,null,msg);

查看消息输出：可以看到partition在0、1、2轮询

2.3、key哈希分区策略

根据消息的key进行哈希计算，partition=null && key != null

ProducerRecord producerRecord = new ProducerRecord(userTopic,null,userDTO.getUserId(),msg);

查看消息输出：

2.4、自定义分区策略（即自定义Partitioner）

3、查看数据文件

userTest-0分区：

userTest-1分区：

userTest-2分区：

schoolTest-0分区：

四、消息类型

1、异步消息

默认为异步消息

1.1、普通异步
kafkaTemplate.send(producerRecord);
1.2、回调异步
package com.example.service.impl;

import com.alibaba.fastjson.JSON;
import com.example.dto.UserDTO;
import com.example.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.support.SendResult;
import org.springframework.stereotype.Service;
import org.springframework.util.concurrent.ListenableFutureCallback;

import java.util.concurrent.ExecutionException;


@Service("userService")
@Slf4j
public class UserServiceImpl implements UserService {

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    @Value("${user.topic}")
    private String userTopic;

    @Override
    public void sendUserMsg(UserDTO userDTO) {
        String msg = JSON.toJSONString(userDTO);
        ProducerRecord producerRecord = new ProducerRecord(userTopic,null,userDTO.getUserId(),msg);
        //1.1、普通异步
        //kafkaTemplate.send(producerRecord);
        //1.2、回调异步
        kafkaTemplate.send(producerRecord).addCallback(new ListenableFutureCallback<SendResult<String, String>>() {
            @Override
            public void onSuccess(SendResult<String, String> result) {
                // 消息成功发送的逻辑
                log.info("Message sent successfully to the topic:{} ",result.getRecordMetadata().topic());
            }

            @Override
            public void onFailure(Throwable ex) {
                // 消息发送失败的逻辑
                log.error("Error sending message:{}", ex.getMessage());
            }
        });
        //2、同步
        /*try {
            kafkaTemplate.send(producerRecord).get();
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } catch (ExecutionException e) {
            throw new RuntimeException(e);
        }*/

        log.info("user消息发送成功");
    }
}
2、同步消息

末尾加get为同步发送

kafkaTemplate.send(producerRecord).get();
3、顺序消息

如这里按age大小发送消息，希望接收到的age是有序的：则将age相同的发送到同一个partition

ProducerRecord producerRecord = new ProducerRecord(userTopic,null,String.valueOf(userDTO.getAge()),msg);
        kafkaTemplate.send(producerRecord);
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