分页的第二种方式

优点：

1.代码十分简洁

缺点:

1.不能及时响应数据库中变化

2.重复查询较多，每获取一个属性（总页数），都要查找数据库

将某一页的数据直接封装在此类中，调一个方法便可获取数据。

public class fengye {

// 查询所有用户

public List<User> selecthouse() {

// TODO Auto-generated method stub

Session session = HibernateUtil.getSession();

// 开启事物

Transaction tran = session.beginTransaction();

String hql = "from User";

Query q = session.createQuery(hql);

List<User> list = q.list();

HibernateUtil.closeSession();

return list;

}

// 计算页数

public int getTotalPages(int count, int pageSize) {

int totalpages = 0;

totalpages = (count % pageSize == 0) ? (count / pageSize) : (count

/ pageSize + 1);

return totalpages;

}

// 获取用户数

public int getConut() {

Session session = HibernateUtil.getSession();

Transaction tran = session.beginTransaction();

String hql = "select count(*) from User";

Query q = session.createQuery(hql);

List list = q.list();

String li = list.get(0).toString();

Integer count = Integer.parseInt(li);

HibernateUtil.closeSession();

return count;

}

// 获取当前页的记录

public List<User> selechouse(int pageIndex, int pageSize) {

Session session = HibernateUtil.getSession();

// 开启事物

Transaction tran = session.beginTransaction();

String hql = "from User";

Query query = session.createQuery(hql);

query.setFirstResult((pageIndex - 1) * pageSize);

query.setMaxResults(pageSize);

List<User> result = query.list();

HibernateUtil.closeSession();

return result;

}

}

JSP页面：

<%

//设置每页显示条数

int pageSize = 3;

//实例化

fengye newxw = new fengye();

//获取表中有多少条数据

int count = newxw.getConut();

//获取页码

String page1 = request.getParameter("pageIndex");

//得到分页数目

int pag = newxw.getTotalPages(count, pageSize);

//得到当前页码

int pageIndex = 0;

//判断得到的值是否有值

if (page1 == null) {

pageIndex = 1;

} else {

//把当前页赋值给pageIndex

pageIndex = Integer.parseInt(page1);

//判断当前页是否为最大页

if (pageIndex > pag) {

pageIndex = pag;

}

}

List<User> list = newxw.selechouse(pageIndex, pageSize);

request.setAttribute("list", list);

%>

<table id="cs_table" class="datatable">

<thead>

<tr>

<th>名称</th>

<th>性别</th>

<th>地址</th>

</tr>

</thead>

<tbody>

<c:forEach items="${requestScope.list}" var="mind" varStatus="id">

<tr>

<td>${mind.username}</td>

<td>${mind.sex}</td>

<td>${mind.address}</td>

</tr>

</c:forEach>

</tbody>

</table>

<div id="fy">

<%

//判断当前页是否为末页

if (pageIndex > 1) {

%>

<a href="page1.jsp?pageIndex=<%=1%>"> 首页</a> <a

href="index.jsp?pageIndex=<%=pageIndex - 1%>"> 上一页 </a>

<%

}

//判断当前页是否为首页

if (pageIndex < pag) {

%>

<a href="page1.jsp?pageIndex=<%=pageIndex + 1%>"> 下一页</a> <a

href="page1.jsp?pageIndex=<%=pag%>"> 末页 </a>

<%

}

%>

[<%=pageIndex%>/<%=pag%>]页

</div>

改进版：性能更优化，代码更简洁。

为页面数据新建一个类

public class PageData {

private int count;

private int pageIndex;

private int totalPages;

private List<User> list;

｝省略get/set

此类减少到一个核心方法，将数据放入PageData对象中。

public class fengye {

private PageData data;

public fengye(){

data=new PageData();

}

public PageData getData(int pageIndex,int pageSize){

Session session = HibernateUtil.getSession();

// 开启事物

Transaction tran = session.beginTransaction();

String hql = "from User";

Query q = session.createQuery(hql);

List<User> list = q.list();

Integer count = list.size();

int totalpages = 0;

totalpages = (count % pageSize == 0) ? (count / pageSize) : (count

/ pageSize + 1);

data.setTotalPages(totalpages);

if(pageIndex>totalpages){

pageIndex=totalpages;

}

q.setFirstResult((pageIndex - 1) * pageSize);

q.setMaxResults(pageSize);

list = q.list();

data.setList(list);

data.setPageIndex(pageIndex);

data.setCount(count);

HibernateUtil.closeSession();

return data;

}

}

JSP

//设置每页显示条数

int pageSize = 3;

//实例化

fengye newxw = new fengye();

//得到当前页码

int pageIndex = 0;

//获取页码

String page1 = request.getParameter("pageIndex");

//判断传来的参数是否有值

if (page1 == null) {

pageIndex = 1;

} else {

//把当前页赋值给pageIndex

pageIndex = Integer.parseInt(page1);

//判断当前页是否为最大页

}

//获取表中有多少条数据

int count ;

//得到分页数目

int pag;

PageData data=newxw.getData(pageIndex, pageSize);

count=data.getCount();

page1=""+data.getPageIndex();

pag=data.getTotalPages();

List<User> list = data.getList();

request.setAttribute("list", list);