News新闻发布系统分页的实现
1.首先我们要在NewsDAO中创建一个方法，返回List<NewsEntity>集合,其中pageIndex表示当前页，pageSize表示新闻数量
public List<NewsEntity> GetSelect(int pageIndex,int pageSize);
2.NewsDAOImpl类实现了NewsDAO，所以自然继承了GetSelect()方法
public List<NewsEntity> GetSelect(int pageIndex,int pageSize)
{
List<NewsEntity> list=new ArrayList<NewsEntity>();
String sql="select top "+pageSize+" * from newsDetial where newsId not in(select top "+(pageIndex-1)*pageSize+" newsId from newsDetial)";
ResultSet rs=executeQuery(sql);
if(rs!=null)
{
while(rs.next())
{
NewsEntity entity=new NewsEntity();
entity.setNewsId(rs.getInt("newsId")); entity.setNewsTitle(rs.getString("newsTitle")); entity.setNewsContent(rs.getString("newsContent")); entity.setNewsCreateDate(rs.getDate("newsCreateDate")); entity.setNewsAuthor(rs.getString("newsAuthor")); entity.setNewsCateforyId(rs.getInt("newsCategoryId")); list.add(entity);
}
}
return list;
}
3.然后我们新建一个Util包，包中有page方法，来存储向用户展示的数据
public class page
{
//当前页
private int pageIndex;
//页面记录数
private int pageSize;
//本页显示真实数据
private List<NewsEntity> list;
//总页数
private int totalPages;
//总记录数
private int totalRecords;
}
4.在NewsServlet类中，实现其功能(当给总页数赋值时，需要在NewsDAO中新建一个getAllCount方法，在NewsDaoImpl中实现其方法)
public int getAllCount() throws Exception {
int result=0;
String sql="select count(1) as num from newsDetails";
ResultSet rs=executeQuery(sql);
if(rs!=null)
{
if(rs.next())
{
result=rs.getInt("num");
}
closeAll();
}
return result;
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
NewsDAOImpl news=new NewsDAOImpl();
try {
page pages=new page();
//默认显示三条数据
int pageSize=3;
pages.setPageSize(pageSize);
//当前页
int myIndex;
String pageIndex=request.getParameter("pageIndex");
if(pageIndex!=null)
{
myIndex=Integer.parseInt(pageIndex);
}
else
{
myIndex=1;
}
//给当前页赋值
pages.setPageIndex(myIndex);
//总页数
int mytotalPage=0;
int totalPage=news.getAllCount();
if(totalPage%pageSize==0)
{
mytotalPage=totalPage/pageSize;
}
else
{
mytotalPage=totalPage/pageSize+1;
}
pages.setTotalPages(mytotalPage);
//查询所有
//List<NewsEntity> list=news.Select();
//request.setAttribute("list", list);
//泛型数据
List<NewsEntity> list=news.getSelect(pages.getPageIndex(), pageSize);
pages.setList(list);
request.setAttribute("list", pages);
//登录
String name=request.getParameter("uname");
String pwd=request.getParameter("upwd");
boolean flag= news.Login(name, pwd);
if(flag)
{
response.sendRedirect("newspages/admin.jsp");
}
else
{
request.getRequestDispatcher("/index.jsp").forward(request, response);
}
request.getRequestDispatcher("/index.jsp").forward(request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
<ul class="classlist">
<%
//从作用域中取出一个泛型
page page2= (page)request.getAttribute("list");
for(NewsEntity item :page2.getList()){
//一个item就是一个新闻对象
%>
<li><a href='<%=path %>/newspages/news_read.jsp'> <%=item.getNewsTitle() %> </a><span> <%=item.getNewsCreateDate() %> </span></li>
<% }
%>
<p align="right"> 当前页数:[<%=page2.getPageIndex() %>/<%=page2.getTotalPages() %>] <a href="<%=path %>/Servlet/NewsServlet?pageIndex=<%=page2.getPageIndex()+1%>">下一页</a> <a href="#">末页</a> </p>
</ul>
其中，page2.getPageIndex()代表当前页码，page2.getTotalPages()代表了总页码，当点击下一页的时候page2.getPageIndex()要加1