Redis actual combat expert explores the store and likes it

Redis actual combat expert explores the store and likes it

a demand

Users can like or unlike blogs, and a user can only like once

two realization

  @Override
    public 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;
        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 + 1
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            // 3.2.保存用户到Redis的set集合  zadd key value score
            if (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 -1
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            // 4.2.把用户从Redis的set集合移除
            if (isSuccess) {
    
    
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();
    }