内存分页

public static <T> PageResult<T> newPage(List<T> content, Integer pageNum, Integer pages) {

    int total = content.size();
    int offset = (pageNum -1 ) *  pages;

    if (offset > total) {
        return new PageResult<T>(null, pageNum, pages, (long)total);
    }
    final List<T> paged = content.subList(offset, Math.min(total, offset + pages));

    return new PageResult<T>(paged, pageNum, pages, (long)total);
}