分页工具类

public class PageUtil {
    private PageUtil() {
        // 工具类私有构造方法
    }

    /**
     * 内存分页
     *
     * @param page
     * @param pageSize
     * @param filterDtoList
     * @param <T>
     * @return
     */
    public static <T> PageResult<T> getPageResult(Integer page, Integer pageSize, List<T> filterDtoList) {
        Integer total = filterDtoList.size();
        int start = pageSize * (page - 1);
        int end = start + pageSize;
        if (start > total) {
            return new PageResult<>();
        }
        if (end > total) {
            end = total;
        }
        List<T> subList = filterDtoList.isEmpty() ? filterDtoList : filterDtoList.subList(start, end);

        PageResult<T> pageResult = new PageResult<>(page, pageSize, total.longValue());
        pageResult.setData(subList);
        return pageResult;
    }


    /**
     * 获取真实page,主要当页码超过真实页码后取最后一页
     *
     * @param totalNum
     * @param currentPage
     * @param pageSize
     * @return
     */
    public static int getRealPage(long totalNum, int currentPage, int pageSize) {
        if (totalNum < 1) {
            return 1;
        }
        int totalPage = (int) (totalNum + (long) pageSize - 1L) / pageSize;
        if (currentPage <= totalPage) {
            return currentPage;
        }
        return totalPage;
    }
}