*/
    protected void calculatePageInfo() {
        int startWithOffset = start - offset;
        if (startWithOffset < 0) {
            startWithOffset = 0;
        }
        allPageCount = (int) ((allRecordCount - 1) / pageSize) + 1;
        existPrevPage = startWithOffset > 0;
        existNextPage = startWithOffset < (long) (allPageCount - 1) * (long) pageSize;
        currentPageNumber = start / pageSize + 1;