一、添加kafka依赖
在https://mvnrepository.com/中搜索kafka,我们使用spring本身支持的依赖spring-kafka。
这里面需要注意点版本的问题,参考下图做对比,不同版本的springboot支持不同版本的kafka:
也可以自己去官方看这个对应关系:https://spring.io/projects/spring-kafka/
对比上图去maven仓库找相应版本就可以了:https://mvnrepository.com/
我的springboot版本是2.2.5的,所以使用kafka的版本如下所示:
<!-- https://mvnrepository.com/artifact/org.springframework.kafka/spring-kafka -->
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
<version>2.3.5.RELEASE</version>
</dependency>
如果版本不对应会有很多的问题,通常kafka的版本要比springboot高一个版本就行了,比如2.2.5则kafka是2.3.5这样。
二、添加配置文件
我这里使用一个共工程模拟生产者和消费者。
我的springboot工程使用的配置文件是yaml类型的,所以按照如下方式添加:
spring:
kafka:
bootstrap-servers: 192.168.184.134:9092,192.168.184.135:9092,192.168.184.136:9092
producer:
# 发生错误后,消息重发的次数。
retries: 0
# 键的序列化方式
key-serializer: org.apache.kafka.common.serialization.StringSerializer
# 值的序列化方式
value-serializer: org.apache.kafka.common.serialization.StringSerializer
consumer:
group-id: test
# 键的反序列化方式
key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
# 值的反序列化方式
value-deserializer: org.apache.kafka.common.serialization.StringDeserializer
listener:
# 但消费者监听的topic不存在时,保证能够是项目启动
missing-topics-fatal: false
配置还有很多,我们这里先集成,后面会逐渐增加配置。
三、代码实现
3.1生产者
package com.cloud.bssp.message.kafka.producer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Component;
/**
* kafka生产者
*
* @author weirx
* @date 2021/02/03 14:22
**/
@Component
public class KafkaProducer {
@Autowired
private KafkaTemplate kafkaTemplate;
/**
* kafka消息发送
* @param
* @author weirx
* @return void
* @date: 2021/2/3
*/
public void send(String topic){
kafkaTemplate.send(topic,"hello kafka");
}
}
3.2消费者
package com.cloud.bssp.message.kafka.consumer;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;
import java.util.Optional;
/**
* kafka消费者
*
* @author weirx
* @date 2021/02/03 15:01
**/
@Slf4j
@Component
public class KafkaConsumer {
@KafkaListener(topics = {"test-kafka"})
public void consumer(ConsumerRecord<?, ?> record) {
Optional<?> kafkaMessage = Optional.ofNullable(record.value());
if (kafkaMessage.isPresent()) {
Object message = kafkaMessage.get();
log.info("----------------- record =" + record);
log.info("------------------ message =" + message);
}
}
}
3.3测试类
package com.cloud.bssp.message.kafka;
import com.cloud.bssp.message.kafka.producer.KafkaProducer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* kafka测试类
*
* @author weirx
* @date 2021/02/03 15:03
**/
@RestController
@RequestMapping("test/kafka")
public class TestKafka {
@Autowired
private KafkaProducer producer;
@RequestMapping("/send/{topic}")
public void send(@PathVariable String topic){
producer.send(topic);
}
}
四、测试
这里我将topic作为了参数进行传递,方便我们观察。
我们执行以下测试接口:
http://localhost:8085/test/kafka/send/test-kafka
看下控制台,消费者输出的结果:
2021-02-03 17:12:44.654 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 5, leaderEpoch = 0, offset = 0, CreateTime = 1612343564622, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:12:44.654 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
从上结果看到:
topic:test-kafka
partition:5
offset:0
我们从kafkatool中看看结果,在分区5中增加了一条消息:
这里为什么有10个分区呢?在上一章节我们搭建kafka集群的时候,默认给了10个partition,关于partition的作用,在我们学会使用后,后面的章节会详细介绍。
offset是当前partition中的数据个数的偏移量,从0开始。
下面我们再次发送10条消息,使消息再次发送到partition5中。结果如下:
2021-02-03 17:15:17.129 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 9, leaderEpoch = 0, offset = 0, CreateTime = 1612343717117, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:15:17.129 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:20:45.456 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 0, leaderEpoch = 0, offset = 0, CreateTime = 1612344045453, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:20:45.456 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:12.999 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 4, leaderEpoch = 0, offset = 0, CreateTime = 1612344072988, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:12.999 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:15.983 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 3, leaderEpoch = 0, offset = 0, CreateTime = 1612344075980, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:15.983 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:16.799 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 2, leaderEpoch = 0, offset = 0, CreateTime = 1612344076796, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:16.799 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:17.614 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 1, leaderEpoch = 0, offset = 0, CreateTime = 1612344077612, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:17.614 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:18.487 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 8, leaderEpoch = 0, offset = 0, CreateTime = 1612344078484, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:18.487 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:19.527 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 7, leaderEpoch = 0, offset = 0, CreateTime = 1612344079524, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:19.527 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:20.505 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 6, leaderEpoch = 0, offset = 0, CreateTime = 1612344080500, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:20.505 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
2021-02-03 17:21:21.440 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ----------------- record =ConsumerRecord(topic = test-kafka, partition = 5, leaderEpoch = 0, offset = 1, CreateTime = 1612344081437, serialized key size = -1, serialized value size = 11, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = hello kafka)
2021-02-03 17:21:21.440 INFO 5080 --- [ntainer#0-0-C-1] c.c.b.m.kafka.consumer.KafkaConsumer : ------------------ message =hello kafka
如上结果,又发送了10条消息,消息随机的负载到每个partition中,第10条再次记录到了partition 5中,其offset加1了。
到此为止,已经完成了springboot和kafka的集成了,后面会逐渐深入到每个特性和组件。