Kafka笔记大纲

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SpringBoot 是一个在 JavaEE 开发中非常常用的组件。可以用于 Kafka 的生产者，也可以用于 SpringBoot 的消费者

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一、SpringBoot 环境准备

1.1.创建一个 Spring Initializr

1.2.引入场景启动器：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>


    <groupId>com.jianqun</groupId>
    <artifactId>springboot-kafka</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-kafka</name>
    <description>springboot-kafka</description>


    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.6.13</spring-boot.version>
    </properties>


    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>


    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.jianqun.springbootkafka.SpringbootKafkaApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

1.3.编写配置文件：

# 应用服务 WEB 访问端口
server.port=8080

# 应用名称
spring.application.name=jianqun_springboot_kafka

# 指定 kafka 的地址
spring.kafka.bootstrapservers=hadoop102:9092,hadoop103:9092,hadoop104:9092

# 生产者配置
# 指定 key 和 value 的序列化器
spring.kafka.producer.keyserializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.valueserializer=org.apache.kafka.common.serialization.StringSerializer


# 消费者配置
# 指定 key 和 value 的反序列化器
spring.kafka.consumer.keydeserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.valuedeserializer=org.apache.kafka.common.serialization.StringDeserializer
# 指定消费者组的 group_id
spring.kafka.consumer.group-id=jianqun
# =========消费者配置结束=========

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二、编写生产端消息：

• 1.编写controller接口，当收到请求的时候，模式发送一条数据到kafka中

package com.jianqun.springbootkafka.kafka;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.web.bind.annotation.RequestMapping;

public class ProducerController {

    // Kafka 模板用来向 kafka 发送数据
    @Autowired
    KafkaTemplate<String, String> kafka;

    @RequestMapping("/a")
    public String data() {
        String msg = "生产端消息";
        kafka.send("firstopic", msg);
        return "ok";
    }
}

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三、编写消费者端消息：

• 1.消费者代码：

package com.jianqun.springbootkafka.kafka;

import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.annotation.KafkaListener;

@Configuration
public class KafkaConsumer {
    // 指定要监听的 topic
    @KafkaListener(topics = "firstopic")
    public void consumeTopic(String msg) {
        // 参数: 收到的 value
        System.out.println("收到的信息: " + msg);
    }
}

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四、测试：