hibernate和struts2实现分页功能

1.DAO层接口的设计，定义一个PersonDAO接口，里面声明了两个方法：

public interface PersonDAO
{
    public List<Person> queryByPage(String hql, int offset, int pageSize);

    public int getAllRowCount(String hql);
}

2.DAO层接口的实现类PersonDAOImpl类，将其两个方法实现出来：

public class PersonDAOImpl implements PersonDAO
{
    /**
     * 通过hql语句得到数据库中记录总数
     */
    @Override
    public int getAllRowCount(String hql)
    {
        Session session = HibernateUtil.openSession();
        Transaction tx = null;
        int allRows = ;
        try
        {
            tx = session.beginTransaction();

            Query query = session.createQuery(hql);

            allRows = query.list().size();

            tx.commit();

        }
        catch (Exception e)
        {
            if(tx != null)
            {
                tx.rollback();
            }

            e.printStackTrace();
        }
        finally
        {
            HibernateUtil.closeSession(session);
        }

        return allRows;
    }
    /**
     * 使用hibernate提供的分页功能，得到分页显示的数据
     */
    @SuppressWarnings("unchecked")
    @Override
    public List<Person> queryByPage(String hql, int offset, int pageSize)
    {
        Session session = HibernateUtil.openSession();
        Transaction tx = null;
        List<Person> list = null;

        try
        {
            tx = session.beginTransaction();

            Query query = session.createQuery(hql).setFirstResult(offset).setMaxResults(pageSize);

            list = query.list();

            tx.commit();

        }
        catch (Exception e)
        {
            if(tx != null)
            {
                tx.rollback();
            }

            e.printStackTrace();
        }
        finally
        {
            HibernateUtil.closeSession(session);
        }

        return list;
    }
}

3.定义了一个PageBean(每一页所需要的内容都存放在这个PageBean里面)，里面用来存放网页每一页显示的内容：

public class PageBean
{
    private List<Person> list; //通过hql从数据库分页查询出来的list集合

    private int allRows; //总记录数

    private int totalPage; //总页数

    private int currentPage; //当前页

    public List<Person> getList()
    {
        return list;
    }

    public void setList(List<Person> list)
    {
        this.list = list;
    }

    public int getAllRows()
    {
        return allRows;
    }

    public void setAllRows(int allRows)
    {
        this.allRows = allRows;
    }

    public int getTotalPage()
    {
        return totalPage;
    }

    public void setTotalPage(int totalPage)
    {
        this.totalPage = totalPage;
    }

    public int getCurrentPage()
    {
        return currentPage;
    }

    public void setCurrentPage(int currentPage)
    {
        this.currentPage = currentPage;
    }

    /**
     * 得到总页数
     * @param pageSize 每页记录数
     * @param allRows  总记录数
     * @return 总页数
     */
    public int getTotalPages(int pageSize, int allRows)
    {
        int totalPage = (allRows % pageSize == )? (allRows / pageSize): (allRows / pageSize) + ;

        return totalPage;
    }

    /**
     * 得到当前开始记录号
     * @param pageSize 每页记录数
     * @param currentPage 当前页
     * @return
     */
    public int getCurrentPageOffset(int pageSize, int currentPage)
    {
        int offset = pageSize * (currentPage - );

        return offset;
    }

    /**
     * 得到当前页， 如果为0 则开始第一页，否则为当前页
     * @param page
     * @return
     */
    public int getCurPage(int page)
    {
        int currentPage = (page == )? : page;

        return currentPage;
    }

}

4.Service层接口设计，定义一个PersonService接口，里面声明了一个方法，返回一个PageBean：

public interface PersonService
{
    public PageBean getPageBean(int pageSize, int page);
}

5.Service层接口实现类PersonServiceImpl类，实现唯一的方法：

public class PersonServiceImpl implements PersonService
{
    private PersonDAO personDAO = new PersonDAOImpl();

    /**
     * pageSize为每页显示的记录数
     * page为当前显示的网页
     */
    @Override
    public PageBean getPageBean(int pageSize, int page)
    {
        PageBean pageBean = new PageBean();

        String hql = "from Person";

        int allRows = personDAO.getAllRowCount(hql);

        int totalPage = pageBean.getTotalPages(pageSize, allRows);

        int currentPage = pageBean.getCurPage(page);

        int offset = pageBean.getCurrentPageOffset(pageSize, currentPage);

        List<Person> list = personDAO.queryByPage(hql, offset, pageSize);

        pageBean.setList(list);
        pageBean.setAllRows(allRows);
        pageBean.setCurrentPage(currentPage);
        pageBean.setTotalPage(totalPage);

        return pageBean;
    }
}

6.Action层设计，定义一个PersonAction：

public class PersonAction extends ActionSupport
{
    private PersonService personService = new PersonServiceImpl();

    private int page;

    public int getPage()
    {
        return page;
    }

    public void setPage(int page)
    {
        this.page = page;
    }

    @Override
    public String execute() throws Exception
    {
        //表示每页显示5条记录，page表示当前网页
        PageBean pageBean = personService.getPageBean(, page);

        HttpServletRequest request = ServletActionContext.getRequest();

        request.setAttribute("pageBean", pageBean);

        return SUCCESS;
    }
}

7.辅助类设计，HibernateUtil:

public class HibernateUtil
{
    private static SessionFactory sessionFactory;

    static
    {
        sessionFactory = new Configuration().configure().buildSessionFactory();
    }

    public static Session openSession()
    {
        Session session = sessionFactory.openSession();

        return session;
    }

    public static void closeSession(Session session)
    {
        if(session != null)
        {
            session.close();
        }
    }

}

8.最后也就是分页页面显示pagePerson.jsp：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>

<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP 'pagePerson.jsp' starting page</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">

    <script type="text/javascript">

        function validate()
        {
            var page = document.getElementsByName("page")[].value;

            if(page > <s:property value="#request.pageBean.totalPage"/>)
            {
                alert("你输入的页数大于最大页数，页面将跳转到首页！");

                window.document.location.href = "personAction";

                return false;
            }

            return true;
        }

    </script>

  </head>

  <body>

    <h1><font color="blue">分页查询</font></h1><hr>

    <table border="" align="center" bordercolor="yellow" width="50%">

        <tr>
            <th>序号</th>
            <th>姓名</th>
            <th>年龄</th>
        </tr>

    <s:iterator value="#request.pageBean.list" id="person">

        <tr>
            <th><s:property value="#person.id"/></th>
            <th><s:property value="#person.name"/></th>
            <th><s:property value="#person.age"/></th>
        </tr>

    </s:iterator>

    </table>

    <center>

        <font size="">共<font color="red"><s:property value="#request.pageBean.totalPage"/></font>页 </font>&nbsp;&nbsp;
        <font size="">共<font color="red"><s:property value="#request.pageBean.allRows"/></font>条记录</font><br><br>

        <s:if test="#request.pageBean.currentPage == 1">
            首页&nbsp;&nbsp;&nbsp;上一页
        </s:if>

        <s:else>
            <a href="personAction.action">首页</a>
            &nbsp;&nbsp;&nbsp;
            <a href="personAction.action?page=<s:property value="#request.pageBean.currentPage - "/>">上一页</a>
        </s:else>

        <s:if test="#request.pageBean.currentPage != #request.pageBean.totalPage">
            <a href="personAction.action?page=<s:property value="#request.pageBean.currentPage + "/>">下一页</a>
            &nbsp;&nbsp;&nbsp;
            <a href="personAction.action?page=<s:property value="#request.pageBean.totalPage"/>">尾页</a>
        </s:if>

        <s:else>
            下一页&nbsp;&nbsp;&nbsp;尾页
        </s:else>

    </center><br>

    <center>

        <form action="personAction" onsubmit="return validate();">
            <font size="">跳转至</font>
            <input type="text" size="" name="page">页
            <input type="submit" value="跳转">
        </form>

    </center>

  </body>
</html>

至此，hibernate+struts2实现网页分页功能代码部分就完毕了，像hibernate与struts的配置文件就不列出来了，那些都不是重点！

页面效果如下: