问答平台（7），热帖排行

问题背景

热帖排行-图示
将分数变化的帖子放入 Redis 缓存中，每5分钟定时任务刷新帖子的分数。

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- 热帖排行功能的实现需要定时，即每隔段时间就要从数据库中查询最热门的帖子显示，所以使用定时任务来实现。
- JDK的ScheduledExecutorService 和 Spring的ThreadPoolTaskScheduler 都可以实现定时任务，但是在分布式的环境下会出现问题。
- 本项目采用Quartz, quartz实现定时任务的参数是存到数据库中（同一个DB）。

工具类

  • RedisKeyUtil: 添加内容
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    private static final String PREFIX_POST = "post";

    // 帖子分数
    public static String getPostScoreKey() {
        return PREFIX_POST + SPLIT + "score";
    }

表现层

  • DiscussPostController: 修改（计算帖子分数）
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    @Autowired
    private RedisTemplate redisTemplate;

    @RequestMapping(path = "/add", method = RequestMethod.POST)
    @ResponseBody
    public String addDiscussPost(String title, String content) {
        User user = hostHolder.getUser();
        if (user == null) {
            return CommunityUtil.getJSONString(403, "还没有登录!");
        }

        DiscussPost post = new DiscussPost();
        post.setUserId(user.getId());
        post.setTitle(title);
        post.setContent(content);
        post.setCreateTime(new Date());
        discussPostService.addDiscussPost(post);

        // 触发发帖事件
        Event event = new Event()
                .setTopic(TOPIC_PUBLISH)
                .setUserId(user.getId())
                .setEntityType(ENTITY_TYPE_POST)
                .setEntityId(post.getId());
        eventProducer.fireEvent(event);

        // 计算帖子分数
        String redisKey = RedisKeyUtil.getPostScoreKey();
        redisTemplate.opsForSet().add(redisKey, post.getId());

        // 报错的情况，将来统一处理
        return CommunityUtil.getJSONString(0, "发布成功!");
    }

    // 加精
    @RequestMapping(path = "/wonderful", method = RequestMethod.POST)
    @ResponseBody
    public String setWonderful(int id) {
        discussPostService.updateStatus(id, 1);

        // 触发发帖事件
        Event event = new Event()
                .setTopic(TOPIC_PUBLISH)
                .setUserId(hostHolder.getUser().getId())
                .setEntityType(ENTITY_TYPE_POST)
                .setEntityId(id);
        eventProducer.fireEvent(event);

        // 计算帖子分数
        String redisKey = RedisKeyUtil.getPostScoreKey();
        redisTemplate.opsForSet().add(redisKey, id);

        return CommunityUtil.getJSONString(0);
    }
  • CommentController: 修改
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    @Autowired
    private RedisTemplate redisTemplate;

    @RequestMapping(path = "/add/{discussPostId}", method = RequestMethod.POST)
    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);

        if (comment.getEntityType() == ENTITY_TYPE_POST) {
            // 触发发帖事件
            event = new Event()
                    .setTopic(TOPIC_PUBLISH)
                    .setUserId(comment.getUserId())
                    .setEntityType(ENTITY_TYPE_POST)
                    .setEntityId(discussPostId);
            eventProducer.fireEvent(event);

            // 计算帖子分数
            String redisKey = RedisKeyUtil.getPostScoreKey();
            redisTemplate.opsForSet().add(redisKey, discussPostId);
        }

        return "redirect:/discuss/detail/" + discussPostId;
    }
  • LikeController: 修改
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    @Autowired
    private RedisTemplate redisTemplate;

    @RequestMapping(path = "/like", method = RequestMethod.POST)
    @ResponseBody
    public String like(int entityType, int entityId, int entityUserId, int 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) {
            Event event = new Event()
                    .setTopic(TOPIC_LIKE)
                    .setUserId(hostHolder.getUser().getId())
                    .setEntityType(entityType)
                    .setEntityId(entityId)
                    .setEntityUserId(entityUserId)
                    .setData("postId", postId);
            eventProducer.fireEvent(event);
        }

        if (entityType == ENTITY_TYPE_POST) {
            // 计算帖子分数
            String redisKey = RedisKeyUtil.getPostScoreKey();
            redisTemplate.opsForSet().add(redisKey, postId);
        }

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

quartz

  • PostScoreRefreshJob: 新增
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    // 定时任务
    public class PostScoreRefreshJob implements Job, CommunityConstant {

        private static final Logger logger = LoggerFactory.getLogger(PostScoreRefreshJob.class);

        @Autowired
        private RedisTemplate redisTemplate;

        @Autowired
        private DiscussPostService discussPostService;

        @Autowired
        private LikeService likeService;

        @Autowired
        private ElasticsearchService elasticsearchService;

        // 牛客纪元
        private static final Date epoch;

        static {
            try {
                epoch = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2014-08-01 00:00:00");
            } catch (ParseException e) {
                throw new RuntimeException("初始化牛客纪元失败!", e);
            }
        }

        @Override
        public void execute(JobExecutionContext context) throws JobExecutionException {
            String redisKey = RedisKeyUtil.getPostScoreKey();
            BoundSetOperations operations = redisTemplate.boundSetOps(redisKey);

            if (operations.size() == 0) {
                logger.info("[任务取消] 没有需要刷新的帖子!");
                return;
            }

            logger.info("[任务开始] 正在刷新帖子分数: " + operations.size());
            while (operations.size() > 0) {
                this.refresh((Integer) operations.pop());
            }
            logger.info("[任务结束] 帖子分数刷新完毕!");
        }

        private void refresh(int postId) {
            DiscussPost post = discussPostService.findDiscussPostById(postId);

            if (post == null) {
                logger.error("该帖子不存在: id = " + postId);
                return;
            }

            // 是否精华
            boolean wonderful = post.getStatus() == 1;
            // 评论数量
            int commentCount = post.getCommentCount();
            // 点赞数量
            long likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_POST, postId);

            // 计算权重
            double w = (wonderful ? 75 : 0) + commentCount * 10 + likeCount * 2;
            // 分数 = 帖子权重 + 距离天数
            double score = Math.log10(Math.max(w, 1))
                    + (post.getCreateTime().getTime() - epoch.getTime()) / (1000 * 60 * 60 * 24);
            // 更新帖子分数
            discussPostService.updateScore(postId, score);
            // 同步搜索数据
            post.setScore(score);
            elasticsearchService.saveDiscussPost(post);
        }
    }

config

  • QuartzConfig: 添加内容
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    // 刷新帖子分数任务- 将分数变化的帖子丢到Redis缓存中，每5分钟计算一次帖子的分数。
    @Bean
    public JobDetailFactoryBean postScoreRefreshJobDetail() {
        JobDetailFactoryBean factoryBean = new JobDetailFactoryBean();
        factoryBean.setJobClass(PostScoreRefreshJob.class);
        factoryBean.setName("postScoreRefreshJob");
        factoryBean.setGroup("communityJobGroup");
        factoryBean.setDurability(true);
        factoryBean.setRequestsRecovery(true);
        return factoryBean;
    }

    @Bean
    public SimpleTriggerFactoryBean postScoreRefreshTrigger(JobDetail postScoreRefreshJobDetail) {
        SimpleTriggerFactoryBean factoryBean = new SimpleTriggerFactoryBean();
        factoryBean.setJobDetail(postScoreRefreshJobDetail);
        factoryBean.setName("postScoreRefreshTrigger");
        factoryBean.setGroup("communityTriggerGroup");
        factoryBean.setRepeatInterval(1000 * 60 * 5);
        factoryBean.setJobDataMap(new JobDataMap());
        return factoryBean;
    }

数据访问层

  • DiscussPostMapper: 重构 selectDiscussPosts
  • orderMode: 排序模式（0默认，1热度）
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    int updateScore(int id, double score);
    List<DiscussPost> selectDiscussPosts(int userId, int offset, int limit, int orderMode);
  • discusspost-mapper.xml: 重构
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    <update id="updateScore">
        update discuss_post set score = #{score} where id = #{id}
    </update>

    <select id="selectDiscussPosts" resultType="DiscussPost">
        select
        <include refid="selectFields"></include>
        from discuss_post
        where status != 2
        <if test="userId != 0">
            and user_id = #{userId}
        </if>
        <if test="orderMode==0">
            order by type desc, create_time desc
        </if>
        <if test="orderMode==1">
            order by type desc, score desc, create_time desc
        </if>
        limit #{offset}, #{limit}
    </select>

业务层

  • DiscussPostService: 重构 findDiscussPosts
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    public int updateScore(int id, double score) {
        return discussPostMapper.updateScore(id, score);
    }

    public List<DiscussPost> findDiscussPosts(int userId, int offset, int limit, int orderMode) {
        if (userId == 0 && orderMode == 1) {
            return postListCache.get(offset + ":" + limit);
        }

        logger.debug("load post list from DB.");
        return discussPostMapper.selectDiscussPosts(userId, offset, limit, orderMode);
    }

表现层

  • HomeController: 重构 getIndexPage
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    @RequestMapping(path = "/index", method = RequestMethod.GET)
    public String getIndexPage(Model model, Page page,
                              @RequestParam(name = "orderMode", defaultValue = "0") int orderMode) {
        // 方法调用前，SpringMVC会自动实例化Model和Page，并将Page注入Model
        // 所以，在thymeleaf中可以直接访问Page对象中的数据
        page.setRows(discussPostService.findDiscussPostRows(0));
        page.setPath("/index?orderMode=" + orderMode);

        List<DiscussPost> list = discussPostService
                .findDiscussPosts(0, page.getOffset(), page.getLimit(), orderMode);
        List<Map<String, Object>> discussPosts = new ArrayList<>();
        if (list != null) {
            for (DiscussPost post : list) {
                Map<String, Object> map = new HashMap<>();
                map.put("post", post);
                User user = userService.findUserById(post.getUserId());
                map.put("user", user);

                long likeCount = likeService.findEntityLikeCount(ENTITY_TYPE_POST, post.getId());
                map.put("likeCount", likeCount);

                discussPosts.add(map);
            }
        }
        model.addAttribute("discussPosts", discussPosts);
        model.addAttribute("orderMode", orderMode);

        return "/index";
    }

页面

  • index.html: 修改
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    <!-- 内容 -->
    <!-- 筛选条件 -->
    <li class="nav-item">
        <a th:class="|nav-link ${orderMode==0?'active':''}|" th:href="@{/index(orderMode=0)}">最新</a>
    </li>
    <li class="nav-item">
        <a th:class="|nav-link ${orderMode==1?'active':''}|" th:href="@{/index(orderMode=1)}">最热</a>
    </li>

结果展示

热帖排行展示-图示

#问答平台
问答平台（7），热帖排行
https://lcf163.github.io/2020/06/17/问答平台（7），热帖排行/
作者
乘风的小站
发布于
2020年6月17日
许可协议