报错信息：java.util.ArrayList cannot be cast to com.github.pagehelper.Page
产生原因：
PageHelper.startPage(pageNumber, pageSize);List<String> userIdList = userRoleMapper.selectUserIdByRole();List<Log> list = logDao.selectAllLog();return (Page<Log>)list;
在查询要返回的结果前还进行了一次数据库查询，调整为以下顺序后正确：
List<String> userIdList = userRoleMapper.selectUserIdByRole();PageHelper.startPage(pageNumber, pageSize);List<Log> list = logDao.selectAllLog();return (Page<Log>)list;