基于Redis的Set、Zset类型实现好友关注，共同好友（求并集）

@Override
    public Result follow(Long followUserId, Boolean isFollow) {
        // 1.获取登录用户
        Long userId = UserHolder.getUser().getId();
        String key = "follows:" + userId;
        // 1.判断到底是关注还是取关
        if (isFollow) {
            // 2.关注，新增数据
            Follow follow = new Follow();
            follow.setUserId(userId);
            follow.setFollowUserId(followUserId);
            boolean isSuccess = save(follow);
            if (isSuccess) {
                // 把关注用户的id，放入redis的set集合 sadd userId followerUserId
                stringRedisTemplate.opsForSet().add(key, followUserId.toString());
            }
        } else {
            // 3.取关，删除 delete from tb_follow where user_id = ? and follow_user_id = ?
            boolean isSuccess = remove(new QueryWrapper()
                    .eq("user_id", userId).eq("follow_user_id", followUserId));
            if (isSuccess) {
                // 把关注用户的id从Redis集合中移除
                stringRedisTemplate.opsForSet().remove(key, followUserId.toString());
            }
        }
        return Result.ok();
    }

public Result followCommons(Long id) {
        // 1.获取当前用户
        Long userId = UserHolder.getUser().getId();
        String key = "follows:" + userId;
        // 2.求交集
        String key2 = "follows:" + id;
        Set intersect = stringRedisTemplate.opsForSet().intersect(key, key2);
        if (intersect == null || intersect.isEmpty()) {
            // 无交集
            return Result.ok(Collections.emptyList());
        }
        // 3.解析id集合
        List ids = intersect.stream().map(Long::valueOf).collect(Collectors.toList());
        // 4.查询用户
        List users = userService.listByIds(ids)
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        return Result.ok(users);
    }

public Result saveBlog(Blog blog) {
// 1.获取登录用户
UserDTO user = UserHolder.getUser();
blog.setUserId(user.getId());
// 2.保存探店笔记
boolean isSuccess = save(blog);
if(!isSuccess){
    return Result.fail("新增笔记失败!");
}
// 3.查询笔记作者的所有粉丝 select * from tb_follow where follow_user_id = ?
List follows = followService.query().eq("follow_user_id", user.getId()).list();
// 4.推送笔记id给所有粉丝
for (Follow follow : follows) {
    // 4.1.获取粉丝id
    Long userId = follow.getUserId();
    // 4.2.推送
    String key = FEED_KEY + userId;
    stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
}
// 5.返回id
return Result.ok(blog.getId());
}

/**
max为发布博客的时间戳
offset为偏移量
*/
public Result queryBlogOfFollow(Long max, Integer offset) {
    // 1.获取当前用户
    Long userId = UserHolder.getUser().getId();
    // 2.查询收件箱 ZREVRANGEBYSCORE key Max Min LIMIT offset count
    String key = FEED_KEY + userId;
    Set> typedTuples = stringRedisTemplate.opsForZSet()
    .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
    // 3.非空判断
    if (typedTuples == null || typedTuples.isEmpty()) {
        return Result.ok();
    }
    // 4.解析数据：blogId、minTime（时间戳）、offset
    List ids = new ArrayList(typedTuples.size());
    long minTime = 0; // 2
    int os = 1; // 2
    for (ZSetOperations.TypedTuple tuple : typedTuples) { // 5 4 4 2 2
        // 4.1.获取id
        ids.add(Long.valueOf(tuple.getValue()));
        // 4.2.获取分数(时间戳）
        long time = tuple.getScore().longValue();
        if(time == minTime){
            os++;
        }else{
            minTime = time;
            os = 1;
        }
    }

    // 5.根据id查询blog
    String idStr = StrUtil.join(",", ids);
    List blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();

    for (Blog blog : blogs) {
        // 5.1.查询blog有关的用户
        queryBlogUser(blog);
        // 5.2.查询blog是否被点赞
        isBlogLiked(blog);
    }

    // 6.封装并返回
    ScrollResult r = new ScrollResult();
    r.setList(blogs);
    服务器托管网r.setOffset(os);
    r.setMinTime(minTime);

    return Result.ok(r);
}

Set> typedTuples = stringRedisTemplate.opsForZSet()
.reverseRangeByScoreWithScores(key, 0, max, offset, 2);