某马头条——day06

自媒体文章上下架

使用消息队列在自媒体下架时通知文章微服务。?

kafka概述

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kafka环境搭建

docker pull zookeeper:3.4.14

docker run -d --name zookeeper -p 2181:2181 zookeeper:3.4.14

安装kafka

docker pull wurstmeister/kafka:2.12-2.3.1

docker run -d --name kafka \
--env KAFKA_ADVERTISED_HOST_NAME=192.168.200.130 \
--env KAFKA_ZOOKEEPER_CONNECT=192.168.200.130:2181 \
--env KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://192.168.200.130:9092 \
--env KAFKA_LISTENERS=PLAINTEXT://0.0.0.0:9092 \
--env KAFKA_HEAP_OPTS="-Xmx256M -Xms256M" \
--net=host wurstmeister/kafka:2.12-2.3.1

kafka入门案例

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依赖

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

生产者类?

package com.heima.kafka.sample;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;

import java.util.Properties;

/**
 * 生产者
 */
public class ProducerQuickStart {

    public static void main(String[] args) {
        //1.kafka的配置信息
        Properties properties = new Properties();
        //kafka的连接地址
        properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.200.130:9092");
        //发送失败，失败的重试次数
        properties.put(ProducerConfig.RETRIES_CONFIG,5);
        //消息key的序列化器
        properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringSerializer");
        //消息value的序列化器
        properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringSerializer");

        //2.生产者对象
        KafkaProducer<String,String> producer = new KafkaProducer<String, String>(properties);

        //封装发送的消息
        ProducerRecord<String,String> record = new ProducerRecord<String, String>("itheima-topic","100001","hello kafka");

        //3.发送消息
        producer.send(record);

        //4.关闭消息通道，必须关闭，否则消息发送不成功
        producer.close();
    }

}

?消费者类

package com.heima.kafka.sample;

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 java.time.Duration;
import java.util.Collections;
import java.util.Properties;

/**
 * 消费者
 */
public class ConsumerQuickStart {

    public static void main(String[] args) {
        //1.添加kafka的配置信息
        Properties properties = new Properties();
        //kafka的连接地址
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.200.130:9092");
        //消费者组
        properties.put(ConsumerConfig.GROUP_ID_CONFIG, "group2");
        //消息的反序列化器
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");

        //2.消费者对象
        KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(properties);

        //3.订阅主题
        consumer.subscribe(Collections.singletonList("itheima-topic"));

        //当前线程一直处于监听状态
        while (true) {
            //4.获取消息
            ConsumerRecords<String, String> consumerRecords = consumer.poll(Duration.ofMillis(1000));
            for (ConsumerRecord<String, String> consumerRecord : consumerRecords) {
                System.out.println(consumerRecord.key());
                System.out.println(consumerRecord.value());
            }
        }

    }

}

存在一个消费者组和多个消费者组的区别

?分区机制

相当于数据分片？redis也有这个机制。

高可用设计方案

kafka生产者详解

发送类型

参数详解

acks=0和UDP很像

kafka消费者详解

多个分区无法保证消息的有序性，相当于，a先后发了两条消息给b，两条消息进了不同的分区，结果因为网络原因导致b先接收到了第二条消息。

提交和偏移量

这里因为不是每次消费都提交就会出现丢失和重复的问题。

偏移量提交方式

SpringBoot集成kafka收发消息

1.导入spring-kafka依赖信息

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- kafkfa -->
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.apache.kafka</groupId>
                <artifactId>kafka-clients</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
    </dependency>
</dependencies>

2.在resources下创建文件application.yml

server:
  port: 9991
spring:
  application:
    name: kafka-demo
  kafka:
    bootstrap-servers: 192.168.200.130:9092
    producer:
      retries: 10
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.apache.kafka.common.serialization.StringSerializer
    consumer:
      group-id: ${spring.application.name}-test
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer

?3.消息生产者

package com.heima.kafka.controller;

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 HelloController {

    @Autowired
    private KafkaTemplate<String,String> kafkaTemplate;

    @GetMapping("/hello")
    public String hello(){
        kafkaTemplate.send("itcast-topic","黑马程序员");
        return "ok";
    }
}

4.消息消费者

package com.heima.kafka.listener;

import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

@Component
public class HelloListener {

    @KafkaListener(topics = "itcast-topic")
    public void onMessage(String message){
        if(!StringUtils.isEmpty(message)){
            System.out.println(message);
        }

    }
}

传递消息为对象时

发送

@GetMapping("/hello")
public String hello(){
    User user = new User();
    user.setUsername("xiaowang");
    user.setAge(18);

    kafkaTemplate.send("user-topic", JSON.toJSONString(user));

    return "ok";
}

接受

@Component
public class HelloListener {

    @KafkaListener(topics = "user-topic")
    public void onMessage(String message){
        if(!StringUtils.isEmpty(message)){
            User user = JSON.parseObject(message, User.class);
            System.out.println(user);
        }

    }
}

自媒体文章上下架功能实现

• 已发表且已上架的文章可以下架

• 已发表且已下架的文章可以上架

流程说明

?文章表存在一个属性字段是否上架

功能接口开发

在heima-leadnews-wemedia工程下的WmNewsController新增方法

@PostMapping("/down_or_up")
public ResponseResult downOrUp(@RequestBody WmNewsDto dto){
    return wmNewsService.downOrUp(dto);
}

在WmNewsDto中新增enable属性?

    /**
     * 上下架 0 下架  1 上架
     */
    private Short enable;

在WmNewsService新增方法

/**
 * 文章的上下架
 * @param dto
 * @return
 */
public ResponseResult downOrUp(WmNewsDto dto);

实现方法

/**
 * 文章的上下架
 * @param dto
 * @return
 */
@Override
public ResponseResult downOrUp(WmNewsDto dto) {
    //1.检查参数
    if(dto.getId() == null){
        return ResponseResult.errorResult(AppHttpCodeEnum.PARAM_INVALID);
    }

    //2.查询文章
    WmNews wmNews = getById(dto.getId());
    if(wmNews == null){
        return ResponseResult.errorResult(AppHttpCodeEnum.DATA_NOT_EXIST,"文章不存在");
    }

    //3.判断文章是否已发布
    if(!wmNews.getStatus().equals(WmNews.Status.PUBLISHED.getCode())){
        return ResponseResult.errorResult(AppHttpCodeEnum.PARAM_INVALID,"当前文章不是发布状态，不能上下架");
    }

    //4.修改文章enable
    if(dto.getEnable() != null && dto.getEnable() > -1 && dto.getEnable() < 2){
        update(Wrappers.<WmNews>lambdaUpdate().set(WmNews::getEnable,dto.getEnable())
                .eq(WmNews::getId,wmNews.getId()));
    }
    return ResponseResult.okResult(AppHttpCodeEnum.SUCCESS);
}

测试通过

消息通知article数据同步

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在heima-leadnews-common模块下导入kafka依赖

<!-- kafkfa -->
<dependency>
    <groupId>org.springframework.kafka</groupId>
    <artifactId>spring-kafka</artifactId>
</dependency>
<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
</dependency>

在自媒体端的nacos配置中心配置kafka的生产者

spring:
  kafka:
    bootstrap-servers: 192.168.200.130:9092
    producer:
      retries: 10
      key-serializer: org.apache.kafka.common.serialization.StringSerializer
      value-serializer: org.apache.kafka.common.serialization.StringSerializer

在自媒体端文章上下架后发送消息

//发送消息，通知article端修改文章配置
if(wmNews.getArticleId() != null){
    Map<String,Object> map = new HashMap<>();
    map.put("articleId",wmNews.getArticleId());
    map.put("enable",dto.getEnable());
    kafkaTemplate.send(WmNewsMessageConstants.WM_NEWS_UP_OR_DOWN_TOPIC,JSON.toJSONString(map));
}

在article端的nacos配置中心配置kafka的消费者

spring:
  kafka:
    bootstrap-servers: 192.168.200.130:9092
    consumer:
      group-id: ${spring.application.name}
      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value-deserializer: org.apache.kafka.common.serialization.StringDeserializer

在article端编写监听，接收数据

import com.alibaba.fastjson.JSON;
import com.heima.article.service.ApArticleConfigService;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

import java.util.Map;

@Component
@Slf4j
public class ArtilceIsDownListener {

    @Autowired
    private ApArticleConfigService apArticleConfigService;

    @KafkaListener(topics = WmNewsMessageConstants.WM_NEWS_UP_OR_DOWN_TOPIC)
    public void onMessage(String message){
        if(StringUtils.isNotBlank(message)){
            Map map = JSON.parseObject(message, Map.class);
            apArticleConfigService.updateByMap(map);
            log.info("article端文章配置修改，articleId={}",map.get("articleId"));
        }
    }
}

新建ApArticleConfigService

public interface ApArticleConfigService extends IService<ApArticleConfig> {

    /**
     * 修改文章配置
     * @param map
     */
    public void updateByMap(Map map);
}

实现

@Service
@Slf4j
@Transactional
public class ApArticleConfigServiceImpl extends ServiceImpl<ApArticleConfigMapper, ApArticleConfig> implements ApArticleConfigService {


    /**
     * 修改文章配置
     * @param map
     */
    @Override
    public void updateByMap(Map map) {
        //0 下架 1 上架
        Object enable = map.get("enable");
        boolean isDown = true;
        if(enable.equals(1)){
            isDown = false;
        }
        //修改文章配置
        update(Wrappers.<ApArticleConfig>lambdaUpdate().eq(ApArticleConfig::getArticleId,map.get("articleId")).set(ApArticleConfig::getIsDown,isDown));

    }
}

测试成功tmd