Kafka 本质上是⼀个消息队列。与zeromq不同的是,Kafka是一个独立的框架而不是一个库。这里主要介绍其原理,至于具体的安装等操作不做介绍,只是提示一下,第一次运行时,先设置前台运行,看会不会报错。
https://kafka.apache.org/downloads
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# the directory where the snapshot is stored.
dataDir=/kingpi/kafka/data
# the port at which the clients will connect
clientPort=2181
# disable the per-ip limit on the number of connections since this is a non-production config
maxClientCnxns=0
# Disable the adminserver by default to avoid port conflicts.
# Set the port to something non-conflicting if choosing to enable this
admin.enableServer=false
# admin.serverPort=8080
./bin/zookeeper-server-start.sh -daemon /kingpi/kafka/kafka_2.12-2.8.2/config/zookeeper.properties
#默认0,有集群的话会有1,2等。每个broker都要唯一哈,否则起不来的。
broker.id=0
#需要这样配置到当前服务器上,切记//后面无需加参数即可
listeners=PLAINTEXT://:9092
#需要配置当前的服务器IP用于外部客户端使用,否则会提示无法连接,启动spring boot的时候会连接本地的kafka导致无法连接的错误:[Producer clientId=producer-1] Error while fetching metadata with correlation id 95 : {topic=INVALID_REPLICATION_FACTOR}
advertised.listeners=PLAINTEXT://CURRENT_IP:9092
#连接指定的zk即可
zookeeper.connect=localhost:2181
./bin/kafka-server-start.sh -daemon /kingpi/kafka/kafka_2.12-2.8.2/config/server.properties
代码如下(示例):
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
<version>2.8.0</version>
</dependency>
代码如下(示例):
server:
port: 8989
servlet:
context-path: /
spring:
application:
name: kafka-service
kafka:
bootstrap-servers: IP:9092
producer: # producer 生产者
retries: 0 # 重试次数
acks: 1 # 应答级别:多少个分区副本备份完成时向生产者发送ack确认(可选0、1、all/-1)
batch-size: 16384 # 批量大小
buffer-memory: 33554432 # 生产端缓冲区大小
key-serializer: org.apache.kafka.common.serialization.StringSerializer
value-serializer: org.apache.kafka.common.serialization.StringSerializer
consumer: # consumer消费者
group-id: javagroup # 默认的消费组ID
enable-auto-commit: true # 是否自动提交offset
auto-commit-interval: 100 # 提交offset延时(接收到消息后多久提交offset)
# earliest:当各分区下有已提交的offset时,从提交的offset开始消费;无提交的offset时,从头开始消费
# latest:当各分区下有已提交的offset时,从提交的offset开始消费;无提交的offset时,消费新产生的该分区下的数据
# none:topic各分区都存在已提交的offset时,从offset后开始消费;只要有一个分区不存在已提交的offset,则抛出异常
auto-offset-reset: latest
key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
value-deserializer: org.apache.kafka.common.serialization.StringDeserializer
package com.hh.kafka.config;
import org.apache.kafka.clients.admin.NewTopic;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.config.TopicBuilder;
/**
* @Description: kafka配置类
* @Author: raoqinhao
* @Date: 2022-12-30 15:52
*/
@Configuration
public class KafkaConfig {
@Bean
public NewTopic topic() {
return TopicBuilder.name("topic").build();
}
}
package com.hh.kafka.controller;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
/**
* @Description: TODO
* @Author: raoqinhao
* @Date: 2022-12-30 15:50
*/
@RestController
@RequestMapping("/kafka")
public class KafkaController {
@Resource
public KafkaTemplate<String, String> kafkaTemplate;
@PostMapping("/sendMessage")
public Boolean productMessage() {
String data = "{\"name\":\"zhangsan\"}";
kafkaTemplate.send("topic", data); // 注意这里发送这个topic如果不存在会自动创建的,存在就不会。
return Boolean.TRUE;
}
}
package com.hh.kafka.consumer;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;
/**
* @Description: TODO
* @Author: raoqinhao
* @Date: 2022-12-30 15:55
*/
@Component
public class KafkaConsumer {
@KafkaListener(topics = {"topic"}, groupId = "javagroup")
public void onMessage1(ConsumerRecord<?, ?> record){
// 消费的哪个topic、partition的消息,打印出消息内容
System.out.println("简单消费:"+record.topic()+"-"+record.partition()+"-"+record.value());
}
}
[root@localhost kafka_2.12-2.8.2]# ./bin/kafka-topics.sh --zookeeper 127.0.0.1:2181 --list
[root@localhost kafka_2.12-2.8.2]# ./bin/kafka-topics.sh --create --topic topic --partitions 1 --replication-factor 1 --zookeeper localhost:2181
[root@localhost kafka_2.12-2.8.2]# ./bin/kafka-topics.sh --delete --topic topic --zookeeper localhost:2181
[root@localhost kafka_2.12-2.8.2]# ./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic topic
[root@localhost kafka_2.12-2.8.2]# ./bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic topic --from-beginning
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