Redis实现点赞

部分实体类

@TableId(value = "id", type = IdType.AUTO)private Long id;/*** 商户id*/private Long shopId;/*** 用户id*/private Long userId;/*** 用户图标*/@TableField(exist = false)private String icon;/*** 用户姓名*/@TableField(exist = false)private String name;/*** 是否点赞过了*/@TableField(exist = false)private Boolean isLike;

逻辑层代码（没有实现排行榜时的代码.使用Set）

 //打开一个博客时调用该方法，可以进行是否高亮展示@Overridepublic Result queryBlogById(Long id) {//查询blogBlog blog = getById(id);if(blog==null){return Result.fail("笔记不存在");}queryBlogUser(blog);//查询blog是否被点赞，返回给前端让前端进行判断是否高亮显示isBlogLiked(blog);return Result.ok(blog);}//给类中判断是否已经点赞的字段isLike赋值private void isBlogLiked(Blog blog) {//1.获取登录用户Long userId = UserHolder.getUser().getId();//2.判断当前登录用户是否已经点赞String key = "blog:liked" + blog.getId();Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());blog.setIsLike(BooleanUtil.isTrue(isMember));}//通过另外一张表，给类中对应数据库表中不存在的两个字段赋值private void queryBlogUser(Blog blog) {//查询blog有关的用户Long userId = blog.getUserId();User user = userService.getById(userId);blog.setName(user.getNickName());blog.setIcon(user.getIcon());}//点击点赞按钮时，执行该方法，进行点赞与取消点赞@Overridepublic Result likeBlog(Long id) {//1.获取登录用户Long userId = UserHolder.getUser().getId();//2.判断当前登录用户是否已经点赞String key = "blog:liked" + id;Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());if(BooleanUtil.isFalse(isMember)){//3.如果未点赞，可以点赞//3.1 数据库点赞数加1boolean isSuccess = this.update().setSql("liked = liked + 1").eq("id", id).update();//3.2 保存用户到Redis的set集合if(isSuccess){stringRedisTemplate.opsForSet().add(key, userId.toString());}}else {//4.如果已点赞取消点赞//4.1数据库点赞数-1boolean isSuccess = this.update().setSql("liked = liked - 1").eq("id", id).update();//4.2 把用户从Redis的set集合中移除if(isSuccess){stringRedisTemplate.opsForSet().remove(key, userId.toString());}}return Result.ok();}

逻辑层代码（实现排行榜时的代码，使用了SortedSet）

    //打开一个博客时调用该方法，可以进行是否高亮展示@Overridepublic Result queryBlogById(Long id) {//查询blogBlog blog = getById(id);if(blog==null){return Result.fail("笔记不存在");}queryBlogUser(blog);//查询blog是否被点赞，返回给前端让前端进行判断是否高亮显示isBlogLiked(blog);return Result.ok(blog);}//给类中判断是否已经点赞的字段isLike赋值private void isBlogLiked(Blog blog) {//1.获取登录用户UserDTO user = UserHolder.getUser();if(user==null){//用户未登录，无需查询是否点赞return;}Long userId = user.getId();//2.判断当前登录用户是否已经点赞String key = BLOG_LIKED_KEY + blog.getId();Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());blog.setIsLike(score != null);}//通过另外一张表，给类中对应数据库表中不存在的两个字段赋值private void queryBlogUser(Blog blog) {//查询blog有关的用户Long userId = blog.getUserId();User user = userService.getById(userId);blog.setName(user.getNickName());blog.setIcon(user.getIcon());}//点击点赞按钮时，执行该方法，进行点赞与取消点赞@Overridepublic Result likeBlog(Long id) {//1.获取登录用户Long userId = UserHolder.getUser().getId();//2.判断当前登录用户是否已经点赞String key = BLOG_LIKED_KEY + id;//查询出的score为空，就为未点赞Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());if(score == null){//3.如果未点赞，可以点赞//3.1 数据库点赞数加1boolean isSuccess = this.update().setSql("liked = liked + 1").eq("id", id).update();//3.2 保存用户到Redis的SortedSet集合 zadd key value scoreif(isSuccess){stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());}}else {//4.如果已点赞取消点赞//4.1数据库点赞数-1boolean isSuccess = this.update().setSql("liked = liked - 1").eq("id", id).update();//4.2 把用户从Redis的set集合中移除if(isSuccess){stringRedisTemplate.opsForZSet().remove(key, userId.toString());}}return Result.ok();}@Overridepublic Result queryBlogByLikes(Long id) {// 1.查询top5的点赞用户 zrange key 0 4String key = BLOG_LIKED_KEY + id;Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);if(top5 == null || top5.isEmpty()){return Result.ok(Collections.emptyList());}//2.解析出其中的用户idList<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());String idStr = StrUtil.join(",", ids);//3. 根据用户id查询用户  where id IN ( 5 , 1 ) order by field (id , 5 ,1) 用于指定id先执行哪个List<UserDTO> userDTOS = userService.query().in("id",ids).last("ORDER BY FIELD(id," + idStr  + ")").list().stream().map(user -> BeanUtil.copyProperties(user, UserDTO.class)).collect(Collectors.toList());//4.返回return Result.ok(userDTOS);}