• 【牛客讨论区】第五章：kafka

    目录

    1. 阻塞队列

    BlockingQueue

    • 解决线程通信的问题。
    • 阻塞方法：put、take。

    生产者消费者模式

    • 生产者：产生数据的线程。
    • 消费者：使用数据的线程。

    实现类

    • ArrayBlockingQueue
    • LinkedBlockingQueue
    • PriorityBlockingQueue、SynchronousQueue、DelayQueue等

    在这里插入图片描述

    test 目录下新建测试类

    package com.nowcoder.community;

import java.util.Random;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

public class BlockingQueueTests {

    public static void main(String[] args) {
        BlockingQueue<Integer> queue = new ArrayBlockingQueue<>(10);
        new Thread(new Producer(queue)).start();
        new Thread(new Consumer(queue)).start();
        new Thread(new Consumer(queue)).start();
        new Thread(new Consumer(queue)).start();
    }
}
class Producer implements Runnable{

    private BlockingQueue<Integer> queue;

    public Producer(BlockingQueue<Integer> queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        try {
            for (int i = 0; i < 100; i++) {
                queue.put(i);
                System.out.println(Thread.currentThread().getName() + "生产：" + queue.size());
                Thread.sleep(20);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

class Consumer implements Runnable {

    private BlockingQueue<Integer> queue;

    public Consumer(BlockingQueue<Integer> queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        try {
            while (true) {
                queue.take();
                System.out.println(Thread.currentThread().getName() + "消费了：" + queue.size());
                Thread.sleep(new Random().nextInt(1000));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

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    运行 main 方法查看结果

    2. Kafka入门

    Kafka简介

    • Kafka是一个分布式的流媒体平台。
    • 应用：消息系统、日志收集、用户行为追踪、流式处理。

    Kafka特点

    • 高吞吐量、消息持久化、高可靠性、高扩展性。

    Kafka术语

    • Broker、Zookeeper
    • Topic、Partition、Offset
    • Leader Replica 、Follower Replica

    http://kafka.apache.org

    小知识：对硬盘的顺序读取，速度是很快的，甚至要快于对内存的随机读取，这也是 kafka 既能持久化又能高性能的原因

    【配置】
    将素材中的 kafka_2.12-2.2.0.tgz 解压到某个目录即可
    配置一下 E:\kafka_2.12-2.2.0\config 目录下的 zookeeper.properties

    在这里插入图片描述

    dataDir=d:/work/data/zookeeper

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    配置 server.properties
    60行

    log.dirs=d:/work/data/kafka-logs

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    【启动】
    打开一个 cmd ，启动 zookeeper

    C:\Users\15642>e:

E:\>cd e:/kafka_2.12-2.2.0

e:\kafka_2.12-2.2.0>bin\windows\zookeeper-server-start.bat config\zookeeper.properties

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    再打开一个 cmd，启动 kafka

    C:\Users\15642>e:

E:\>cd e:/kafka_2.12-2.2.0

e:\kafka_2.12-2.2.0>bin\windows\kafka-server-start.bat config\server.properties

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    自动创建了对应的文件夹

    在这里插入图片描述

    再打开一个 cmd
    使用 kafka 的生产者，创建主题，发送消息

    C:\Users\15642>e:

E:\>cd e:\kafka_2.12-2.2.0\bin\windows

e:\kafka_2.12-2.2.0\bin\windows>kafka-topics.bat --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic test

e:\kafka_2.12-2.2.0\bin\windows>kafka-topics.bat --list --bootstrap-server localhost:9092
test

e:\kafka_2.12-2.2.0\bin\windows>kafka-console-producer.bat --broker-list localhost:9092 --topic test
>hello
>word

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    再打开一个 cmd
    使用 kafka 的消费者，读取 test 主题下的消息

    C:\Users\15642>e:

E:\>cd kafka_2.12-2.2.0\bin\windows

E:\kafka_2.12-2.2.0\bin\windows>kafka-console-consumer.bat --bootstrap-server localhost:9092 --topic test --from-beginning
hello
word

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    关于Kafka使用的重要提示

    现象：在windows的命令行里启动kafka之后，当关闭命令行窗口时，就会强制关闭kafka。这种关闭方式为暴力关闭，很可能会导致kafka无法完成对日志文件的解锁。届时，再次启动kafka的时候，就会提示日志文件被锁，无法成功启动。
    方案：将kafka的日志文件全部删除，再次启动即可。
    建议：不要暴力关闭kafka，建议通过在命令行执行kafka-server-stop命令来关闭它。
    其他：将来在Linux上部署kafka之后，采用后台运行的方式，就会避免这样的问题。

    【关闭】
    新打开一个 cmd，先关闭 kafka，再关闭 zookeeper

    C:\Users\15642>e:

E:\>cd kafka_2.12-2.2.0\bin\windows

E:\kafka_2.12-2.2.0\bin\windows>kafka-server-stop.bat
删除实例 \\DESKTOP-R3O58DJ\ROOT\CIMV2:Win32_Process.Handle="16672"
实例删除成功。

E:\kafka_2.12-2.2.0\bin\windows>zookeeper-server-stop.bat
删除实例 \\DESKTOP-R3O58DJ\ROOT\CIMV2:Win32_Process.Handle="9048"
实例删除成功。
删除实例 \\DESKTOP-R3O58DJ\ROOT\CIMV2:Win32_Process.Handle="8956"
实例删除成功。
删除实例 \\DESKTOP-R3O58DJ\ROOT\CIMV2:Win32_Process.Handle="7388"
实例删除成功。

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    3. Spring整合Kafka

    引入依赖

    • spring-kafka

    配置Kafka

    • 配置server、consumer

    访问Kafka

    • 生产者
    kafkaTemplate.send(topic, data); 

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    • 消费者
    @KafkaListener(topics = {"test"}) 
public void handleMessage(ConsumerRecord record) {}

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    pom.xml

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

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    E:\kafka_2.12-2.2.0\config 下的 consumer.properties
    改一下 group.id

    group.id=community-consumer-group

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    application.properties

    # KafkaProperties
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.group-id=community-consumer-group
spring.kafka.consumer.enable-auto-commit=true
spring.kafka.consumer.auto-commit-interval=3000

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    新建测试类

    package com.nowcoder.community;

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@SpringBootTest
public class KafkaTests {

    @Resource
    private KafkaProducer kafkaProducer;

    @Test
    public void testKafka() {
        kafkaProducer.sendMessage("test", "你好");
        kafkaProducer.sendMessage("test", "在吗");

        try {
            Thread.sleep(1000 * 10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

@Component
class KafkaProducer {

    @Resource
    private KafkaTemplate kafkaTemplate;

    public void sendMessage(String topic, String content) {
        kafkaTemplate.send(topic, content);
    }
}

@Component
class KafkaConsumer {

    @KafkaListener(topics = {"test"})
    public void handleMessage(ConsumerRecord record) {
        System.out.println(record.value());
    }
}

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    先启动 zookeeper，再启动 kafka，最后执行测试方法看看能不能读取到信息

    在这里插入图片描述

    4. 发送系统通知

    触发事件

    • 评论后，发布通知
    • 点赞后，发布通知
    • 关注后，发布通知

    处理事件

    • 封装事件对象
    • 开发事件的生产者
    • 开发事件的消费者

    4.1 entity

    package com.nowcoder.community.entity;

import java.util.HashMap;
import java.util.Map;

public class Event {

    private String topic;
    private int userId;
    private int entityType;
    private int entityId;
    private int entityUserId;
    private Map<String, Object> data = new HashMap<>();

    public String getTopic() {
        return topic;
    }
    //改动所有 set 方法，方便连续调用 set.set.set
    public Event setTopic(String topic) {
        this.topic = topic;
        return this;
    }

    public int getUserId() {
        return userId;
    }

    public Event setUserId(int userId) {
        this.userId = userId;
        return this;
    }

    public int getEntityType() {
        return entityType;
    }

    public Event setEntityType(int entityType) {
        this.entityType = entityType;
        return this;
    }

    public int getEntityId() {
        return entityId;
    }

    public Event setEntityId(int entityId) {
        this.entityId = entityId;
        return this;
    }

    public int getEntityUserId() {
        return entityUserId;
    }

    public Event setEntityUserId(int entityUserId) {
        this.entityUserId = entityUserId;
        return this;
    }

    public Map<String, Object> getData() {
        return data;
    }

    public Event setData(String key, Object value) {
        this.data.put(key, value);
        return this;
    }
}

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    新建一个包 event，封装生产者和消费者

    生产者

    package com.nowcoder.community.event;

import com.alibaba.fastjson.JSONObject;
import com.nowcoder.community.entity.Event;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class EventProducer {

    @Resource
    private KafkaTemplate kafkaTemplate;

    // 处理事件
    public void fireEvent(Event event) {
        // 将事件发布到指定的主题
        kafkaTemplate.send(event.getTopic(), JSONObject.toJSONString(event));
    }
}

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    消费者

    CommunityConstant

    //主题：评论
String TOPIC_COMMENT = "comment";
//主题：点赞
String TOPIC_LIKE = "like";
//主题：关注
String TOPIC_FOLLOW = "follow";
//系统用户ID
int SYSTEM_USER_ID = 1;

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    package com.nowcoder.community.event;

import com.alibaba.fastjson.JSONObject;
import com.nowcoder.community.entity.Event;
import com.nowcoder.community.entity.Message;
import com.nowcoder.community.service.MessageService;
import com.nowcoder.community.util.CommunityConstant;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Component
public class EventConsumer implements CommunityConstant {

    public static final Logger logger = LoggerFactory.getLogger(EventConsumer.class);

    @Resource
    private MessageService messageService;

    @KafkaListener(topics = {TOPIC_COMMENT, TOPIC_LIKE, TOPIC_FOLLOW})
    public void handleCommentMessage(ConsumerRecord record) {
        if (record == null || record.value() == null) {
            logger.error("消息的内容为空！");
            return;
        }
        Event event = JSONObject.parseObject(record.value().toString(), Event.class);
        if (event == null) {
            logger.error("消息格式错误！");
            return;
        }
        //发送站内通知
        Message message = new Message();
        message.setFromId(SYSTEM_USER_ID);
        message.setToId(event.getEntityUserId());
        message.setConversationId(event.getTopic());
        message.setCreateTime(new Date());

        Map<String, Object> content = new HashMap<>();
        content.put("userId", event.getUserId());
        content.put("entityType", event.getEntityType());
        content.put("entityId", event.getEntityId());

        if (!event.getData().isEmpty()) {
            for (Map.Entry<String, Object> entry : event.getData().entrySet()) {
                content.put(entry.getKey(), entry.getValue());
            }
        }

        message.setContent(JSONObject.toJSONString(content));
        messageService.addMessage(message);
    }

}

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    4.2 controller

    CommentMapper 补充方法

    Comment selectCommentById(int id);

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    comment-mapper.xml 实现该方法

    <select id="selectCommentById" resultType="Comment">
    select <include refid="selectFields"></include>
    from comment
    where id = #{id}
</select>

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    CommentService 增加方法

    public Comment findCommentById(int id) {
    return commentMapper.selectCommentById(id);
}

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    CommentController

    public class CommentController implements CommunityConstant {

	@Resource
	private EventProducer eventProducer;

	@Resource
    private DiscussPostService discussPostService;

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    完善 addComment 方法

    @PostMapping("/add/{discussPostId}")
public String addComment(@PathVariable("discussPostId") int discussPostId, Comment comment) {
    comment.setUserId(hostHolder.getUser().getId());
    comment.setStatus(0);
    comment.setCreateTime(new Date());
    commentService.addComment(comment);

    //触发评论事件
    Event event = new Event()
            .setTopic(TOPIC_COMMENT)
            .setUserId(hostHolder.getUser().getId())
            .setEntityType(comment.getEntityType())
            .setEntityId(comment.getEntityId())
            .setData("postId", discussPostId);
    if (comment.getEntityType() == ENTITY_TYPE_POST) {
        DiscussPost target = discussPostService.findDiscussPostById(comment.getEntityId());
        event.setEntityUserId(target.getUserId());
    } else if (comment.getEntityType() == ENTITY_TYPE_COMMENT) {
        Comment target = commentService.findCommentById(comment.getEntityId());
        event.setEntityUserId(target.getUserId());
    }
    eventProducer.fireEvent(event);

    return "redirect:/discuss/detail/" + discussPostId;
}

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    LikeController

    public class LikeController implements CommunityConstant {

	@Resource
	private EventProducer eventProducer;

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    完善 like 方法

    @PostMapping("/like")
@ResponseBody
public String like(int entityType, int entityId, int entityUserId, int postId) { //加了一个形参postId
    User user = hostHolder.getUser();
    // 点赞
    likeService.like(user.getId(), entityType, entityId, entityUserId);
    // 数量
    long likeCount = likeService.findEntityLikeCount(entityType, entityId);
    // 状态
    int likeStatus = likeService.findEntityLikeStatus(user.getId(), entityType, entityId);
    // 返回的结果
    Map<String, Object> map = new HashMap<>();
    map.put("likeCount", likeCount);
    map.put("likeStatus", likeStatus);

    //触发点赞事件
    if (likeStatus == 1) { //点赞才触发，取消赞就不用了
        Event event = new Event()
                .setTopic(TOPIC_LIKE)
                .setUserId(hostHolder.getUser().getId())
                .setEntityType(entityType)
                .setEntityId(entityId)
                .setEntityUserId(entityUserId)
                .setData("postId", postId);
        eventProducer.fireEvent(event);
    }

    return CommunityUtil.getJSONString(0, null, map);
}

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    FollowController

    @Resource
private EventProducer eventProducer;

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    完善 follow 方法

    @PostMapping("/follow")
@ResponseBody
public String follow(int entityType, int entityId) {
    User user = hostHolder.getUser();
    followService.follow(user.getId(), entityType, entityId);

    //触发关注事件
    Event event = new Event()
            .setTopic(TOPIC_FOLLOW)
            .setUserId(user.getId())
            .setEntityType(entityType)
            .setEntityId(entityId)
            .setEntityUserId(entityId);
    eventProducer.fireEvent(event);
    
    return CommunityUtil.getJSONString(0, "已关注！");
}

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    discuss-detail.html
    87行

    <a href="javascript:;" th:onclick="|like(this, 1, ${post.id}, ${post.userId}, ${post.id});|" class="text-primary">

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    139行

    <a href="javascript:;" th:onclick="|like(this, 2, ${cvo.comment.id},${cvo.comment.userId}, ${post.id})|" class="text-primary">

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    165行

    <a href="javascript:;" th:onclick="|like(this, 2, ${rvo.reply.id}, ${rvo.reply.userId}, ${post.id})|" class="text-primary">

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    discuss.js

    function like(btn, entityType, entityId, entityUserId, postId) {
    $.post(
        CONTEXT_PATH + "/like",
        {"entityType":entityType, "entityId":entityId, "entityUserId":entityUserId, "postId":postId},
        function (data) {
            data = $.parseJSON(data);
            if (data.code == 0) {
                $(btn).children("i").text(data.likeCount);
                $(btn).children("b").text(data.likeStatus==1?'已赞':'赞');
            } else {
                alert(data.msg);
            }
        }
    );
}

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    ServiceLogAspect
    完善 before 方法

    @Before("pointCut()")
public void before(JoinPoint joinPoint) {
    //日志格式：用户[ip]在[时间点],访问了[com.community.service.xxx()]
    ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
    if (attributes == null) {//增加判空
        return;
    }
    HttpServletRequest request = attributes.getRequest();
    String ip = request.getRemoteHost();
    String now = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
    String target = joinPoint.getSignature().getDeclaringTypeName() + "." + joinPoint.getSignature().getName();
    logger.info(String.format("用户[%s],在[%s],访问了[%s].", ip, now, target));
}

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    启动程序，测试（确保 zookeeper 和 kafka 已经提前启动了），登陆之后随便找个帖子进行回帖，给评论点赞、关注某个人

    在这里插入图片描述

    去数据库 message 表中查看是否有数据

    在这里插入图片描述

    5. 显示系统通知

    通知列表

    • 显示评论、点赞、关注三种类型的通知

    通知详情

    • 分页显示某一类主题所包含的通知

    未读消息

    • 在页面头部显示所有的未读消息数量

    5.1 通知列表

    MessageMapper
    增加三个方法

    //查询某个主题下最新的通知
Message selectLatestNotice(@Param("userId") int userId, @Param("topic") String topic);

//查询某个主题所包含的通知的数量
int selectNoticeCount(@Param("userId") int userId, @Param("topic") String topic);

//查询未读的通知的数量
int selectNoticeUnreadCount(@Param("userId") int userId, @Param("topic") String topic);

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    message-mapper.xml
    实现三个方法

    <select id="selectLatestNotice" resultType="Message">
    select <include refid="selectFields"></include>
    from message
    where id in (
        select max(id) from message
        where status != 2
        and from_id = 1
        and to_id = #{userId}
        and conversation_id = #{topic}
    )
</select>

<select id="selectNoticeCount" resultType="int">
    select count(id) from message
    where status != 2
        and from_id = 1
        and to_id = #{userId}
        and conversation_id = #{topic}
</select>

<select id="selectNoticeUnreadCount" resultType="int">
    select count(id) from message
    where status = 0
        and from_id = 1
        and to_id = #{userId}
        <if test="topic!=null">
            and conversation_id = #{topic}
        </if>
</select>

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    MessageService
    增加方法

    public Message findLatestNotice(int userId, String topic) {
    return messageMapper.selectLatestNotice(userId, topic);
}

public int findNoticeCount(int userId, String topic) {
    return messageMapper.selectNoticeCount(userId, topic);
}

public int findNoticeUnreadCount(int userId, String topic) {
    return messageMapper.selectNoticeUnreadCount(userId, topic);
}

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    MessageController
    增加方法

    public class MessageController implements CommunityConstant {

	@GetMapping("/notice/list")
    public String getNoticeList(Model model) {
        User user = hostHolder.getUser();
        //查询评论类的通知
        Message message = messageService.findLatestNotice(user.getId(), TOPIC_COMMENT);
        Map<String, Object> messageVO = new HashMap<>();
        if (message != null) {
            messageVO.put("message", message);

            String content = HtmlUtils.htmlUnescape(message.getContent());
            HashMap<String, Object> data = JSONObject.parseObject(content, HashMap.class);

            messageVO.put("user", userService.findUserById((Integer) data.get("userId")));
            messageVO.put("entityType", data.get("entityType"));
            messageVO.put("entityId", data.get("entityId"));
            messageVO.put("postId", data.get("postId"));

            int count = messageService.findNoticeCount(user.getId(), TOPIC_COMMENT);
            messageVO.put("count", count);

            int unread = messageService.findNoticeUnreadCount(user.getId(), TOPIC_COMMENT);
            messageVO.put("unread", unread);
        }
        model.addAttribute("commentNotice", messageVO);

        //查询点赞类的通知
        message = messageService.findLatestNotice(user.getId(), TOPIC_LIKE);
        messageVO = new HashMap<>();
        if (message != null) {
            messageVO.put("message", message);

            String content = HtmlUtils.htmlUnescape(message.getContent());
            HashMap<String, Object> data = JSONObject.parseObject(content, HashMap.class);

            messageVO.put("user", userService.findUserById((Integer) data.get("userId")));
            messageVO.put("entityType", data.get("entityType"));
            messageVO.put("entityId", data.get("entityId"));
            messageVO.put("postId", data.get("postId"));

            int count = messageService.findNoticeCount(user.getId(), TOPIC_LIKE);
            messageVO.put("count", count);

            int unread = messageService.findNoticeUnreadCount(user.getId(), TOPIC_LIKE);
            messageVO.put("unread", unread);
        }
        model.addAttribute("likeNotice", messageVO);

        //查询关注类的通知
        message = messageService.findLatestNotice(user.getId(), TOPIC_FOLLOW);
        messageVO = new HashMap<>();
        if (message != null) {
            messageVO.put("message", message);

            String content = HtmlUtils.htmlUnescape(message.getContent());
            HashMap<String, Object> data = JSONObject.parseObject(content, HashMap.class);

            messageVO.put("user", userService.findUserById((Integer) data.get("userId")));
            messageVO.put("entityType", data.get("entityType"));
            messageVO.put("entityId", data.get("entityId"));

            int count = messageService.findNoticeCount(user.getId(), TOPIC_FOLLOW);
            messageVO.put("count", count);

            int unread = messageService.findNoticeUnreadCount(user.getId(), TOPIC_FOLLOW);
            messageVO.put("unread", unread);
        }
        model.addAttribute("followNotice", messageVO);

        //查询未读消息数量
        int letterUnreadCount = messageService.findLetterUnreadCount(user.getId(), null);
        model.addAttribute("letterUnreadCount", letterUnreadCount);
        int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);
        model.addAttribute("noticeUnreadCount", noticeUnreadCount);

        return "/site/notice";
    }

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    getLetterList 方法的 return 之前加上两行：

    int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);
model.addAttribute("noticeUnreadCount", noticeUnreadCount);

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    letter.html
    74行

    <a class="nav-link position-relative" th:href="@{/notice/list}">
	系统通知<span class="badge badge-danger" th:text="${noticeUnreadCount}" th:if="${noticeUnreadCount != 0}">27</span>
</a>

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    notice.html
    2行

    <html lang="en" xmlns:th="http://www.thymeleaf.org">

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    8-9行

    <link rel="stylesheet" th:href="@{/css/global.css}" />
<link rel="stylesheet" th:href="@{/css/letter.css}" />

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    15行

    <!-- 头部 -->
<header class="bg-dark sticky-top" th:replace="index::header">

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    197行

    <script th:src="@{/js/global.js}"></script>

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    67行 ul 标签

    <!-- 选项 -->
<ul class="nav nav-tabs mb-3">
	<li class="nav-item">
		<a class="nav-link position-relative" th:href="@{/letter/list}">朋友私信
			<span class="badge badge-danger" th:text="${letterUnreadCount}" th:if="${letterUnreadCount != 0}">3</span>
		</a>
	</li>
	<li class="nav-item">
		<a class="nav-link position-relative active" th:href="@{/notice/list}">
			系统通知<span class="badge badge-danger" th:text="${noticeUnreadCount}" th:if="${noticeUnreadCount != 0}">27</span>
		</a>
	</li>
</ul>

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    82行 ul 标签

    <!-- 通知列表 -->
<ul class="list-unstyled">
	<!--评论类通知-->
	<li class="media pb-3 pt-3 mb-3 border-bottom position-relative" th:if="${commentNotice.message!=null}">
		<span class="badge badge-danger" th:text="${commentNotice.unread!=0?commentNotice.unread:''}">3</span>
		<img src="http://static.nowcoder.com/images/head/reply.png" class="mr-4 user-header" alt="通知图标">
		<div class="media-body">
			<h6 class="mt-0 mb-3">
				<span>评论</span>
				<span class="float-right text-muted font-size-12"
					th:text="${#dates.format(commentNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
			</h6>
			<div>
				<a href="#">
					用户
					<i th:utext="${commentNotice.user.username}">nowcoder</i>
					评论了你的<b th:text="${commentNotice.entityType==1?'帖子':'回复'}">帖子</b> ...
				</a>
				<ul class="d-inline font-size-12 float-right">
					<li class="d-inline ml-2"><span class="text-primary">共 <i th:text="${commentNotice.count}">3</i> 条会话</span></li>
				</ul>
			</div>
		</div>
	</li>
	<!--点赞类通知-->
	<li class="media pb-3 pt-3 mb-3 border-bottom position-relative" th:if="${likeNotice.message!=null}">
		<span class="badge badge-danger" th:text="${likeNotice.unread!=0?likeNotice.unread:''}">3</span>
		<img src="http://static.nowcoder.com/images/head/like.png" class="mr-4 user-header" alt="通知图标">
		<div class="media-body">
			<h6 class="mt-0 mb-3">
				<span>赞</span>
				<span class="float-right text-muted font-size-12"
					  th:text="${#dates.format(likeNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
			</h6>
			<div>
				<a href="#">
					用户
					<i th:utext="${likeNotice.user.username}">nowcoder</i>
					点赞了你的<b th:text="${likeNotice.entityType==1?'帖子':'回复'}">帖子</b> ...
				</a>
				<ul class="d-inline font-size-12 float-right">
					<li class="d-inline ml-2"><span class="text-primary">共 <i th:text="${likeNotice.count}">3</i> 条会话</span></li>
				</ul>
			</div>
		</div>
	</li>
	<!--关注类通知-->
	<li class="media pb-3 pt-3 mb-3 border-bottom position-relative" th:if="${followNotice.message!=null}">
		<span class="badge badge-danger" th:text="${followNotice.unread!=0?followNotice.unread:''}">3</span>
		<img src="http://static.nowcoder.com/images/head/follow.png" class="mr-4 user-header" alt="通知图标">
		<div class="media-body">
			<h6 class="mt-0 mb-3">
				<span>关注</span>
				<span class="float-right text-muted font-size-12"
					  th:text="${#dates.format(followNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
			</h6>
			<div>
				<a href="#">
					用户
					<i th:utext="${followNotice.user.username}">nowcoder</i>
					关注了你 ...</a>
				<ul class="d-inline font-size-12 float-right">
					<li class="d-inline ml-2"><span class="text-primary">共 <i th:text="${followNotice.count}">3</i> 条会话</span></li>
				</ul>
			</div>
		</div>
	</li>					
</ul>

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    5.2 通知详情

    MessageMapper

    //查询某个主题所包含的通知列表
List<Message> selectNotices(@Param("userId") int userId,
                            @Param("topic") String topic,
                            @Param("offset") int offset,
                            @Param("limit") int limit);

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    message-mapper.xml

    <select id="selectNotices" resultType="Message">
    select <include refid="selectFields"></include>
    from message
    where status != 2
    and from_id = 1
    and to_id = #{userId}
    and conversation_id = #{topic}
    order by create_time desc
    limit #{offset}, #{limit}
</select>

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    MessageService

    public List<Message> findNotices(int userId, String topic, int offset, int limit) {
    return messageMapper.selectNotices(userId, topic, offset, limit);
}

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    MessageController

    @GetMapping("/notice/detail/{topic}")
public String getNoticeDetail(@PathVariable("topic") String topic, Page page, Model model) {
    User user = hostHolder.getUser();

    page.setLimit(5);
    page.setPath("/notice/detail/" + topic);
    page.setRows(messageService.findNoticeCount(user.getId(), topic));

    List<Message> noticeList = messageService.findNotices(user.getId(), topic, page.getOffset(), page.getLimit());
    List<Map<String, Object>> noticeVoList = new ArrayList<>();
    if (noticeList != null) {
        for (Message notice : noticeList) {
            Map<String, Object> map = new HashMap<>();
            //通知
            map.put("notice", notice);
            //内容
            String content = HtmlUtils.htmlUnescape(notice.getContent());
            Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
            map.put("user", userService.findUserById((Integer) data.get("userId")));
            map.put("entityType", data.get("entityType"));
            map.put("entityId", data.get("entityId"));
            map.put("postId", data.get("postId"));
            //通知的作者
            map.put("fromUser", userService.findUserById(notice.getFromId()));
            noticeVoList.add(map);
        }
    }
    model.addAttribute("notices", noticeVoList);
    //设置已读
    List<Integer> ids = getLetterIds(noticeList);
    if (!ids.isEmpty()) {
        messageService.readMessage(ids);
    }
    return "/site/notice-detail";
}

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    notice.html
    94行

    <a th:href="@{/notice/detail/comment}">

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    116行

    <a th:href="@{/notice/detail/like}">

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    138行

    <a th:href="@{/notice/detail/follow}">

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    notice-detail.html
    2行

    <html lang="en" xmlns:th="http://www.thymeleaf.org">

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    <link rel="stylesheet" th:href="@{/css/global.css}" />
<link rel="stylesheet" th:href="@{/css/letter.css}" />

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    15行

    <!-- 头部 -->
<header class="bg-dark sticky-top" th:replace="index::header">

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    删除 91-150行的 li 标签

    175-176行

    <script th:src="@{/js/global.js}"></script>
<script th:src="@{/js/letter.js}"></script>

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    70行

    <button type="button" class="btn btn-secondary btn-sm" onclick="back();">返回</button>

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    在最后面多加一个 script 标签

    <script>
	function back() {
		location.href = CONTEXT_PATH + "/notice/list";
	}
</script>

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    76行

    <li class="media pb-3 pt-3 mb-2" th:each="map:${notices}">

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    77行

    <img th:src="${map.fromUser.headerUrl}" class="mr-4 rounded-circle user-header" alt="系统图标">

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    80行

    <strong class="mr-auto" th:utext="${map.fromUser.username}">落基山脉下的闲人</strong>

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    81行

    <small th:text="${#dates.format(map.notice.createTime, 'yyyy-MM-dd HH:mm:ss')}">2019-04-25 15:49:32</small>

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    86行 div 标签

    <div class="toast-body">
	<span th:if="${topic.equals('comment')}">
		用户
		<i th:utext="${map.user.username}">nowcoder</i>
		评论了你的<b th:text="${map.entityType==1?'帖子':'回复'}">帖子</b>,
		<a class="text-primary" th:href="@{|/discuss/detail/${map.postId}|}">点击查看</a> !
	</span>
	<span th:if="${topic.equals('like')}">
		用户
		<i th:utext="${map.user.username}">nowcoder</i>
		点赞了你的<b th:text="${map.entityType==1?'帖子':'回复'}">帖子</b>,
		<a class="text-primary" th:href="@{|/discuss/detail/${map.postId}|}">点击查看</a> !
	</span>
	<span th:if="${topic.equals('follow')}">
		用户
		<i th:utext="${map.user.username}">nowcoder</i>
		关注了你
		<a class="text-primary" th:href="@{|/user/profile/${map.user.id}|}">点击查看</a> !
	</span>
</div>

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    110行

    <!-- 分页 -->
<nav class="mt-5" th:replace="index::pagination">

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    5.3 未读消息

    新建一个拦截器

    package com.nowcoder.community.controller.interceptor;

import com.nowcoder.community.entity.User;
import com.nowcoder.community.service.MessageService;
import com.nowcoder.community.util.HostHolder;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Component
public class MessageInterceptor implements HandlerInterceptor {

    @Resource
    private HostHolder hostHolder;

    @Resource
    private MessageService messageService;

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        User user = hostHolder.getUser();
        if (user != null && modelAndView != null) {
            int letterUnreadCount = messageService.findLetterUnreadCount(user.getId(), null);
            int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);
            modelAndView.addObject("allUnreadCount", letterUnreadCount + noticeUnreadCount);
        }
    }
}

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    配置它
    WebMvcConfig

    @Resource
private MessageInterceptor messageInterceptor;

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(loginTicketInterceptor)
            .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg");

    registry.addInterceptor(loginRequiredInterceptor)
            .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg");

    registry.addInterceptor(messageInterceptor)
            .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg");
}

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    index.html
    30行

    <a class="nav-link position-relative" th:href="@{/letter/list}">消息<span class="badge badge-danger" th:text="${allUnreadCount!=0?allUnreadCount:''}">12</span></a>

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    提前开启 zookeeper 和 kafka，启动项目，测试，登录 niuke，给 hahaha 关注，点赞、评论，再登录 hahaha 查看消息

    在这里插入图片描述

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  • 原文地址：https://blog.csdn.net/QinLaoDeMaChu/article/details/125497298