一段内存储器分页代码

public static Page<SysTreeNode> findChildrenByNodeIdPage(Integer page, Integer limit , int parentId){
        if(page == null){
            page = 1;//页数
        }
        if(limit == null){
            limit = 4;//一页包含多少条内容
        }
        try{
            //拿出所有放在listli
            List<SysTreeNode> list = ServiceManager.sysTreeNodeService.getChildrenDesc(parentId) ;
            //新建返回的list
            List<SysTreeNode> returnList = new ArrayList<SysTreeNode>();
            //拿出总大小
            int totalCount = list.size();
            //内存分页
            for(int i = (page - 1) * limit ;i< totalCount && i<page * limit;i++){
                returnList.add(list.get(i));
            }
            return new Page(page, limit, list.size(), returnList);
        }catch (Exception ex){
            log.error("",ex);
            return null;
        }
    }