//currentPage是外部传进来页数
IPageCutter page = new PageCutter();
page.setCurrentPage(currentPage);
page.setTotalRecord(getAllNewsCount());
List list = listAllNews(page.getPageLength(),page.getCurrentRecord());
//假如page.getPageLength()等于10,page.getCurrentRecord()等于13
//listAllNews方法返回从数据库第13条记录开始,到第23条记录结束的10条记录