mybatis-plus随机查询工具类(二)

/**
 * 随机查询
 *
 * @param mapper 持久层DAO
 * @param limit  随机条数
 * @return java.util.List<T>
 * @author <achao1441470436@gmail.com>
 * @since 2021/8/10 15:30
 */
public static <T> List<T> getAny(BaseMapper<T> mapper, T condition, Integer limit) {
    LambdaQueryWrapper<T> wrapper = Wrappers.lambdaQuery(condition);
    Integer total = mapper.selectCount(wrapper);
    if (limit == null || limit <= 0 || total == 0) {
        return Collections.emptyList();
    }
    List<T> list = Optional.of(limit).filter(l -> l > total).map(l -> mapper.selectList(wrapper)).orElseGet(() -> mapper.selectList(wrapper.last("LIMIT " + new SecureRandom().nextInt(total - (limit - 1)) + "," + limit)));
    Collections.shuffle(list);
    return list;
}