7.Kafka，构建TB级异步消息系统

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。

面试题：写一个生产者消费者实现

public class Test {
    public static void main(String[] args) {
        BlockingQueue<String> queue = new LinkedBlockingDeque<>(10);
        Producer p = new Producer(queue);
        Consumer c = new Consumer(queue);
        new Thread(p,"producer").start();
        new Thread(c,"consumer").start();
    }
}

class Consumer implements Runnable {
    private BlockingQueue<String> queue;
    public Consumer(BlockingQueue<String> queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        try {
            while(true){
                Thread.sleep(20);
                System.out.println("消费者消费了：" + queue.take());
            }
        }catch (InterruptedException e) {
                e.printStackTrace();
            }
    }
}

class Producer implements Runnable{
    private BlockingQueue<String> queue;
    public Producer(BlockingQueue<String> queue){
        this.queue = queue;
    }

    @Override
    public void run() {
        try {
            for (int i = 0; i < 5; i++) {
                String tmp = "a product " + i + " from:" + Thread.currentThread().getName();
                System.out.println("生产者生产了：" + tmp);
                queue.put(tmp);
                Thread.sleep(20);
            }
        }catch (InterruptedException e) {
                e.printStackTrace();
        }
    }
}

2.kafka入门

Kafka简介
- Kafka是一个分布式的消息队列。
- 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：Kafka的服务器
- Zookeeper：管理集群
- Topic：点对点模式中每个消费者拿到的消息都不同，发布订阅模式中消费者可能拿到同一份消息。Kafka采用发布订阅模式，生产者把消息发布到的空间（位置）就叫Topic
- Partition：是对Topic位置的分区，如下图：
- Offset：就是消息在分区中的索引
- Leader Replica：主副本，可以处理请求
- Follower Replica：从副本，只是用作备份

Kafka相关链接：https://kafka.apache.org/

Windows下使用Kafka

　　在2.8以前，kafka安装前需要安装zookeeper。如果不需要额外使用zookeeper其他功能，可以安装2.8以后的版本。

在启动前改一下相关配置：

（1）解压kafka压缩包

（2）config下的zookeeper.properties

（3）config下的server.properties

　　注意启动的时候先zookeeper后kafka，停止的时候先kafka后zookeeper。

(4) 启动zookeeper

cd E:\Software\Kafka\kafka_2.12-3.4.0
bin\windows\zookeeper-server-start.bat config\zookeeper.properties

报错：INFO ZooKeeper audit is disabled. (org.apache.zookeeper.audit.ZKAuditProvider)，需要改zookeeper.properties

（5）启动kafka

bin\windows\kafka-server-start.bat config\server.properties

启动完成后会出现配置的文件夹

(6) 创建主题

bin\windows\kafka-topics.bat --create --topic topicDemo --bootstrap-server localhost:9092

(7)显示所有topic列表

bin\windows\kafka-topics --list --bootstrap-server localhost:9092

(8) 向主题发送消息

E:\Software\Kafka\kafka_2.12-3.4.0>bin\windows\kafka-console-producer.bat --broker-list localhost:9092 --topic topicDemo

(9)消费消息

bin\windows\kafka-console-consumer.bat --bootstrap-server localhost:9092 --topic topicDemo --from-beginning

3.Spring整合Kafka

（1）引入依赖

这里记得spring-kafka的版本对应一下你下载的版本

<dependency>
     <groupId>org.springframework.kafka</groupId>
     <artifactId>spring-kafka</artifactId>
     <version>2.8.3</version>
</dependency>

（2）配置Kafka

在application.properties中配置server、consumer

#KafkaProperties
spring.kafka.bootstrap-servers=localhost:9092
#kafka安装目录下config下consumer.properties中找
spring.kafka.consumer.group-id=test-consumer-group
#是否自动提交消费者offset，消费者是按offset读取数据，这个选项表明要记录offset
spring.kafka.consumer.enable-auto-commit=true
#自动提交的频率，设置为3s
spring.kafka.consumer.auto-commit-interval=3000

（3）访问Kafka

生产者
kafkaTemplate.send(topic, data);
消费者
@KafkaListener(topics = {“test”})
public void handleMessage(ConsumerRecord record) {}

public class KafkaTest {
    @Autowired
    KafkaProducer kafkaProducer;
    @Autowired
    KafkaConsumer kafkaConsumer;
    @Test
    public void testKafka(){
        kafkaProducer.sendMessage("test","hello world");
        kafkaProducer.sendMessage("test","I love java");
        try {
            Thread.sleep(1000*10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

@Component
class KafkaProducer{
    @Autowired
    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());
    }
}

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

（1）封装事件对象

@Data
public class Event {
    //张三给李四点赞-->userId是张三，entityUserId是李四
    private String topic;
    private int userId;
    private int entityId;//哪个实体
    private int entityType;//评论/点赞/关注
    private int entityUserId;//发布实体的人
    private Map<String,Object> data=new HashMap<>();
    public Event setData(String key, Object value) {//注意set方法的修改是为了可以类似sb.append(" ").append(“1”);的操作
        this.data.put(key, value);
        return this;
    }
}

（2）事件生产者

新建event包，在包下新建EventProducer类

@Component
public class EventProducer {
    @Autowired
    private KafkaTemplate kafkaTemplate;
    //处理事件-->发送消息
    public void fireEvent(Event event){
        //将event发送到指定topic
        kafkaTemplate.send(event.getTopic(), JSONObject.toJSONString(event));
    }
}

（3）事件消费者

@Slf4j
@Component
public class EventConsumer{
    //消息最终是要往message表中插入数据
    @Autowired
    private MessageService messageService;
    //三种类型新消息
    //follow队列 关注
    //comment队列 评论
    //like队列 点赞
    @KafkaListener(topics = {TOPIC_LIKE,TOPIC_COMMENT,TOPIC_FOLLOW})
    public void handCommentMessage(ConsumerRecord record){
        if(record==null||record.value()==null){
            log.error("消息的内容为空！");
            return;
        }
        //接收到的消息事件
        Event event= JSONObject.parseObject(record.value().toString(),Event.class);
        if(event==null){
            log.error("消息格式错误！");
            return;
        }
        //发送站内通知，主要是构造message对象
        Message message = new Message();
        //User表中id为1代表系统用户
        message.setFromId(SYSTEM_USER_ID);
        message.setToId(event.getEntityUserId());
        message.setConversationId(event.getTopic());
        message.setCreateTime(new Date());

        //消息内容
        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());
            }
        }
        //消息入库
        message.setContent(JSONObject.toJSONString(content));
        messageService.addMessage(message);
    }
}

（4）处理事件

评论事件：commentController类，在添加评论后添加以下代码

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

点赞事件：likeController类，在点赞后添加以下代码

        //触发点赞事件
        if(likeStatus==1){//取消点赞不用通知
            Event event=new Event();
            event.setTopic(TOPIC_LIKE);
            event.setUserId(hostHolder.getUser().getId());
            event.setEntityType(entityType);
            event.setEntityId(entityId);
            event.setEntityUserId(entityUserId);
            event.setData("postId", postId);
            eventProducer.fireEvent(event);
        }

关注事件：followController类，在关注后添加以下代码

        //触发关注事件
        Event event=new Event();
        event.setTopic(TOPIC_FOLLOW);
        event.setUserId(hostHolder.getUser().getId());
        event.setEntityId(entityId);
        event.setEntityType(entityType);
        event.setEntityUserId(entityId);
        eventProducer.fireEvent(event);

（5）针对方法新增的postId参数，需要调整一些静态资源

dicuss-detail页面：

<li class="d-inline ml-2">
    <a href="javascript:;" th:onclick="|like(this,1,${post.id},${post.userId},${post.id});|" class="text-primary">
        <b th:text="${likeStatus==1?'已赞':'赞'}">赞</b> <i th:text="${likeCount}">11</i>
    </a>
</li>

dicuss.js：

message成功入库：

入库的message的content格式是经过html格式转化的

5.显示系统通知

消息通知页面

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

（1）MessageMapper

//查询某个主题下的最新通知
Message selectLatestNotice(int userId,String topic);//userId：被通知的人
//查询某个主题所包含的通知数量
int selectNoticeCount(int usrId,String topic);
//查询未读的通知数量
int selectNoticeUnreadCount(int userId,String topic);

    <!--查询某个主题下的最新通知-->
    <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>
    <!--查询某个主题所包含的通知数量-->
    <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>
    <!--查询未读的通知数量-->
    <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>

（2）MessageService

    //每个类型的最新通知
    public Message findLatestNotice(int userId,String topic){
        return messageMapper.selectLatestNotice(userId,topic);
    }
    //每个类型的通知数量
    public int findNoticeCount(int userId,String topic){
        return messageMapper.selectNoticeCount(userId,topic);
    }
    //未读通知数量
    public int findNoticeUnreadCount(int userId,String topic){
        return messageMapper.selectNoticeUnreadCount(userId,topic);
    }

（3）MessageController

增加获取通知列表页面方法
最下方系统通知数量noticeUnreadCount两行代码需要加到getLetterList()中

//系统通知页面
    @RequestMapping(path = "/notice/list",method = RequestMethod.GET)
    public String getNoticeList(Model model){
        User user=hostHolder.getUser();
        //评论类通知
        Message message=messageService.findLatestNotice(user.getId(),TOPIC_COMMENT);
        if(message!=null){
            Map<String, Object> messageVO = new HashMap<>();
            messageVO.put("message", message);
            String content = HtmlUtils.htmlUnescape(message.getContent());
            Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
            //content中是事件内容
            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);
        }
        //点赞类通知
        message=messageService.findLatestNotice(user.getId(),TOPIC_LIKE);
        if(message!=null){
            Map<String, Object> messageVO = new HashMap<>();
            messageVO.put("message", message);
            String content = HtmlUtils.htmlUnescape(message.getContent());
            Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
            //content中是事件内容
            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);
        }
        //关注类通知
        message=messageService.findLatestNotice(user.getId(),TOPIC_FOLLOW);
        if(message!=null){
            Map<String, Object> messageVO = new HashMap<>();
            messageVO.put("message", message);
            String content = HtmlUtils.htmlUnescape(message.getContent());
            Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
            //content中是事件内容
            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_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（letter和notice页面都需要有）
        //私信列表
        int letterUnreadCount = messageService.findLetterUnreadCount(user.getId(), null);
        model.addAttribute("letterUnreadCount", letterUnreadCount);
        //系统通知
        int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);//只要status为0
        model.addAttribute("noticeUnreadCount", noticeUnreadCount);
        return "/site/notice";
    }

（4）改写notice.html

　　　　 <!-- 内容 -->
        <div class="main">
            <div class="container">
                <div class="position-relative">
                    <!-- 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>
                </div>

                <!-- 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="${#dates.format(commentNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
                            </h6>
                            <div>
                                <a th:href="@{/notice/detail/comment}">
                                    用户
                                    <i th:utext="${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="${#dates.format(likeNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
                            </h6>
                            <div>
                                <a th:href="@{/notice/detail/like}">
                                    用户
                                    <i th:utext="${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="${#dates.format(followNotice.message.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-28 14:13:25</span>
                            </h6>
                            <div>
                                <a th:href="@{/notice/detail/follow}">
                                    用户
                                    <i th:utext="${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>
            </div>
        </div>

系统通知详情

每个类型的通知详情：即某个主题下的通知列表

（1）MessageMapper

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

 <!--查询某类型通知列表-->
<select id="selectNotices" resultType="Message">
      select <include refid="selectFields"></include>
      from message
      where `status` !=2
      and from_id = 1
      and conversation_id = #{topic}
      order by create_time desc
      limit #{offset},#{limit}
</select>

（2）MessageService

//某类型通知列表
public List<Message> findNotices(int userId,String topic,int offset,int limit){
     return messageMapper.selectNotices(userId,topic,offset,limit);
}

（3）MessageController

新增getNoticeDetail()方法

　　//查询某类型详细 通知列表
    @RequestMapping(path = "/notice/detail/{topic}",method = RequestMethod.GET)
    public String getNoticeDetail(@PathVariable("topic")String topic,Page page,Model model){
        User user=hostHolder.getUser();
        //分页
        page.setLimit(5);
        page.setRows(messageService.findNoticeCount(user.getId(), topic));//通知数量
        page.setPath("/notice/detail/"+topic);
        //查询通知列表
        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 = notice.getContent();
                content = HtmlUtils.htmlUnescape(content);
                HashMap<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"));
                map.put("fromUser",userService.findUserById(notice.getFromId())); //系统名
                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";
    }

（4）改写notice-detail.html

        <!-- 内容 -->
        <div class="main">
            <div class="container">
                <div class="row">
                    <div class="col-8">
                        <h6><b class="square"></b> 系统通知</h6>
                    </div>
                    <div class="col-4 text-right">
                        <button type="button" class="btn btn-secondary btn-sm" onclick="back();">返回</button>
                    </div>
                </div>

                <!-- 通知列表 -->
                <ul class="list-unstyled mt-4">
                    <li class="media pb-3 pt-3 mb-2" th:each="map:${notices}">
                        <img th:src="${map.fromUser.headerUrl}" class="mr-4 rounded-circle user-header" alt="系统图标">
                        <div class="toast show d-lg-block" role="alert" aria-live="assertive" aria-atomic="true">
                            <div class="toast-header">
                                <strong class="mr-auto" th:utext="${map.fromUser.username}">落基山脉下的闲人</strong>
                                <small th:text="${#dates.format(map.notice.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-25 15:49:32</small>
                                <button type="button" class="ml-2 mb-1 close" data-dismiss="toast" aria-label="Close">
                                    <span aria-hidden="true">&times;</span>
                                </button>
                            </div>
                            <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>
                        </div>
                    </li>
                </ul>
                <!-- 分页 -->
                <nav class="mt-5" th:replace="index::pagination">
                    <ul class="pagination justify-content-center">
                        <li class="page-item"><a class="page-link" href="#">首页</a></li>
                        <li class="page-item disabled"><a class="page-link" href="#">上一页</a></li>
                        <li class="page-item active"><a class="page-link" href="#">1</a></li>
                        <li class="page-item"><a class="page-link" href="#">2</a></li>
                        <li class="page-item"><a class="page-link" href="#">3</a></li>
                        <li class="page-item"><a class="page-link" href="#">4</a></li>
                        <li class="page-item"><a class="page-link" href="#">5</a></li>
                        <li class="page-item"><a class="page-link" href="#">下一页</a></li>
                        <li class="page-item"><a class="page-link" href="#">末页</a></li>
                    </ul>
                </nav>
            </div>
        </div>


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

（5）首页头部消息数量

每个请求处理完都要查看，所以用拦截器处理

@Component
public class MessageInterceptor implements HandlerInterceptor {
    @Autowired
    private HostHolder hostHolder;
    @Autowired
    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);//私信未读
            int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);//通知未读
            modelAndView.addObject("allUnreadCount", letterUnreadCount + noticeUnreadCount);//未读总数量
        }
    }
}

将该拦截器添加到config

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
    @Autowired
    private AlphaInterceptor alphaInterceptor;
    @Autowired
    private LoginTicketInterceptor loginTicketInterceptor;
    @Autowired
    private LoginRequiredInterceptor loginRequiredInterceptor;
    @Autowired
    private MessageInterceptor messageInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(alphaInterceptor)
                .excludePathPatterns("/css/*","/js/*","/img/*")
                .addPathPatterns("/register","/login");
                //.order(0); 可以设置拦截器顺序

        registry.addInterceptor(loginTicketInterceptor)
                .excludePathPatterns("/css/*","/js/*","/img/*");

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

最后改下index.html

<li class="nav-item ml-3 btn-group-vertical" th:if="${loginUser!=null}">
    <a class="nav-link position-relative" th:href="@{/letter/list}">消息
        <span class="badge badge-danger" th:text="${allUnreadCount!=0?allUnreadCount:''}">12</span>
    </a>
</li>

posted @ 2023-12-29 20:59 壹索007 阅读(19) 评论(0) 编辑收藏举报

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