// 使用 package java.util.Collections;
    /**
     * Randomly permutes the specified list using a default source of
     * randomness.  All permutations occur with approximately equal
     * likelihood.
     */
    public static void shuffle(List<?> list) {
        Random rnd = r;
        if (rnd == null)
            r = rnd = new Random(); // harmless race.
        shuffle(list, rnd);
    }

 /**
     * 追加Lisit
     *
     * @param key 關鍵字
     * @param list 列表
     * @param expireTime 有效期
     * @return boolean
     */
    public Boolean addAll(String key, List list, Long expireTime) {
        try {
            redisTemplate.opsForList().rightPushAll(key, list);
            redisTemplate.expire(key, expireTime, TimeUnit.SECONDS);
            return true;
        } catch (JedisException e) {
            handleJedisException(e);
            throw e;
        } finally {
            RedisConnectionUtils.unbindConnection(Objects.requireNonNull(redisTemplate.getConnectionFactory()));
        }
    }

/**
     * 構(gòu)建分頁數(shù)據(jù)
     * @param so 入?yún)?
     * @param key redis key
     * @param dayKey 天數(shù)區(qū)間的key
     * @return page
     */
    private IPage<PictureAlbumForUserDTO> buildPage(PublishedPictureAlbumSO so, String key, String dayKey) {
        Long total = redisUtil.listSize(key);
        long toIndex = so.getSize() * so.getPage();
        if (toIndex > total) { // 用戶加載到最后一頁，觸發(fā)【懶加載】
            // 發(fā)現(xiàn)池，加載更多數(shù)據(jù)
            String dayValue = redisUtil.get(dayKey);
            String[] dayValueArray = dayValue.split("#");
            long start = Long.parseLong(dayValueArray[0]) - rangeDay;
            long end = Long.parseLong(dayValueArray[1]) - rangeDay;
            if (appendList(key, dayKey, start, end)) {
                // 遞歸調(diào)用；遞歸后，數(shù)據(jù)追加到redis
                return buildPage(so, key, dayKey);
            } else {
                toIndex = total;
            }
        }
        // 根據(jù)下標獲取redis里面分頁數(shù)據(jù)
        List list = redisUtil.listRange(key, so.getSize() * (so.getPage() - 1), toIndex);
        if (CollectionUtil.isEmpty(list)) {
            return null;
        }
        so.setAlbumIdList(list);
        // 因為進行l(wèi)ist id 分頁，這里默認去數(shù)據(jù)庫里查詢第一頁就行了
        so.setPage(1);
        Page<PictureAlbumForUserDTO> pageData = new Page<>(so.getPage(), so.getSize());
        IPage<PictureAlbumForUserDTO> iPage = baseMapper.findAllActive(pageData, so);
        List<PictureAlbumForUserDTO> dtoList = iPage.getRecords();
        Collections.shuffle(dtoList);
        iPage.setRecords(dtoList);
        iPage.setTotal(total);
        iPage.setSize(so.getSize());
        iPage.setCurrent(so.getPage());
        iPage.setPages((total + so.getSize() - 1) / so.getSize());
        return iPage;
    }

 /**
     * 讀取redis lisit 區(qū)間數(shù)據(jù)
     *
     * @param key 關鍵字
     * @param start 開始下標
     * @param end 結(jié)束下標
     * @return boolean
     */
    public List listRange(String key, long start, long end) {
        try {
            return redisTemplate.opsForList().range(key, start, end);
        } catch (JedisException e) {
            handleJedisException(e);
            throw e;
        } finally {
            RedisConnectionUtils.unbindConnection(Objects.requireNonNull(redisTemplate.getConnectionFactory()));
        }
    }