spring boot3 kafka集群搭建到使用

首先自行安装docker，通过docker容器安装kafka
CentOS 系统 docker安装地址

 1.pom.xml和application.properties或者application.yml文件配置

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

spring:
  kafka:
    bootstrap-servers: [fafka地址1,fafka地址2,....]
#    producer序列化设置
    producer:
      #key序列化设置，设置成json对象
#      key-serializer: org.springframework.kafka.support.serializer.JsonSerializer
#    val序列化设置，设置成json对象
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer

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2.博主安装了kafka ui插件，就直接创建主题了

当前一个集群，因为博主只搭建了一台服务器，也可以称为一个节点

创建主题

没有安装kafka ui，就再main那里启动项目时创建

package com.atguigu.boot3_08_kafka;

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

@EnableKafka //扫描kafka注解,开启基于注解的模式
@SpringBootApplication
public class Boot308KafkaApplication {

    public static void main(String[] args) {
        SpringApplication.run(Boot308KafkaApplication.class, args);
        TopicBuilder.name("my-new-topic")//主题
                .partitions(3)//分区
                .replicas(2)//副本
                .build();
    }

}

副本就是备份，有几节点就可以创建几个副本，副本数量一般采取分区数量-1，只有一个节点就N分区1副本

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 3.在main 加上这个注解@EnableKafka

package com.atguigu.boot3_08_kafka;

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

@EnableKafka //扫描kafka注解,开启基于注解的模式
@SpringBootApplication
public class Boot308KafkaApplication {

    public static void main(String[] args) {
        SpringApplication.run(Boot308KafkaApplication.class, args);

    }

}

---

4.生产者发送消息

package com.atguigu.boot3_08_kafka.controller;

import com.atguigu.boot3_08_kafka.entity.Person;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class KafkaController {

    @Autowired
    private KafkaTemplate kafkaTemplate;

    @GetMapping("/jjj") 
    public String hello() {
        kafkaTemplate.send("tach", 0,"hello","急急急132");//send("主题", 分区号,"key","val")
        return "ok";
    }

    @GetMapping("/odj")
    public String odj() {
        kafkaTemplate.send("tach", 0,"hello",new Person(1L,"odj",19));//对象json需要序列化，可用配置文件配置，也可以在对象中序列化对象
        return "OK";
    }
}

---

5.消费者监听消息

package com.atguigu.boot3_08_kafka.listener;

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

@Component
public class MykafkaListener {

    /**
     * 默认的监听是从最后一个消息开始拿，也就是只会拿新消息，不会拿历史的
     * @KafkaListener(topics = "主题",groupId = "用户组")
     * ConsumerRecord 消费者从 Kafka 获取消息的各种元数据和实际的消息
     * @param record
     */
    @KafkaListener(topics = "tach",groupId = "teach")
    public void listen(ConsumerRecord<?, ?> record) {
        Object key = record.key();
        Object val = record.value();
        System.out.println("收到值key:"+key+"收到值val:"+val);
    }

    /**
     *  想要到历史的消息或者全部消息，只能设置偏移量
     *  @KafkaListener(groupId = "用户组" ,topicPartitions = {设置分区,设置偏移量})
     *  @TopicPartition(topic = "主题" ,partitionOffsets 设置偏移量)
     *  @PartitionOffset(partition = "哪个分区", initialOffset = "从第几个偏移量开始")
     *
     * @param record
     */
    @KafkaListener(groupId = "teach" ,topicPartitions = {
            @TopicPartition(topic = "tach" ,partitionOffsets = {
                    @PartitionOffset(partition = "0", initialOffset = "0")
            })
    })
    public void listens(ConsumerRecord<?, ?> record) {
        Object key = record.key();
        Object val = record.value();
        System.out.println("收到值key:"+key+"收到值val:"+val);
    }
}

最后查看结果

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最后补充一个小知识

groupId = "用户组"

组里的成员是竞争模式

用户组和用户组之间是发布/订阅模式

由zookeeper分配管理

好了可以和面试官吹牛逼了

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课外话

如果是传对象json需要序列化，创建对象时序列化，不推荐太原始重要是很占资源

因为开始我们都配置好了，有对象就会自动序列化

package com.atguigu.boot3_08_kafka.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;


@AllArgsConstructor
@NoArgsConstructor
@Data
public class Person implements Serializable {//不推荐implements Serializable 
    private Long id;
    private String name;
    private Integer age;
}