使用hibernate和struts2實現分頁功能

想着每天能學個新東西，今天准備了這個hibernate+struts2實現頁面的分頁功能，在這里，首先要感謝

http://www.blogjava.net/rongxh7/archive/2008/11/29/243456.html

這位博友發表的博文，通過對他代碼的閱讀，從而自己實現了網頁分頁功能，以下是源代碼，如大家有需要，可以回復我，我會放出源代碼供大家下載！

1.DAO層接口的設計，定義一個PersonDAO接口，里面聲明了兩個方法：

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

2.DAO層接口的實現類PersonDAOImpl類，將其兩個方法實現出來：

public class PersonDAOImpl implements PersonDAO
{
    /**
     * 通過hql語句得到數據庫中記錄總數
     */
    @Override
    public int getAllRowCount(String hql)
    {
        Session session = HibernateUtil.openSession();
        Transaction tx = null;
        int allRows = 0;
        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提供的分頁功能，得到分頁顯示的數據
     */
    @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.定義了一個PageBean(每一頁所需要的內容都存放在這個PageBean里面)，里面用來存放網頁每一頁顯示的內容：

public class PageBean
{
    private List<Person> list; //通過hql從數據庫分頁查詢出來的list集合
    
    private int allRows; //總記錄數
    
    private int totalPage; //總頁數
    
    private int currentPage; //當前頁

    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;
    }
    
    /**
     * 得到總頁數
     * @param pageSize 每頁記錄數
     * @param allRows  總記錄數
     * @return 總頁數
     */
    public int getTotalPages(int pageSize, int allRows)
    {
        int totalPage = (allRows % pageSize == 0)? (allRows / pageSize): (allRows / pageSize) + 1;
        
        return totalPage;
    }
    
    /**
     * 得到當前開始記錄號
     * @param pageSize 每頁記錄數
     * @param currentPage 當前頁
     * @return
     */
    public int getCurrentPageOffset(int pageSize, int currentPage)
    {
        int offset = pageSize * (currentPage - 1);
        
        return offset;
    }
    
    /**
     * 得到當前頁， 如果為0 則開始第一頁，否則為當前頁
     * @param page
     * @return
     */
    public int getCurPage(int page)
    {
        int currentPage = (page == 0)? 1: page;
        
        return currentPage;
    }
    
}

4.Service層接口設計，定義一個PersonService接口，里面聲明了一個方法，返回一個PageBean：

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

5.Service層接口實現類PersonServiceImpl類，實現唯一的方法：

public class PersonServiceImpl implements PersonService
{
    private PersonDAO personDAO = new PersonDAOImpl();
    
    /**
     * pageSize為每頁顯示的記錄數
     * page為當前顯示的網頁
     */
    @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層設計，定義一個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
    {
        //表示每頁顯示5條記錄，page表示當前網頁
        PageBean pageBean = personService.getPageBean(5, page);
        
        HttpServletRequest request = ServletActionContext.getRequest();
        
        request.setAttribute("pageBean", pageBean);
        
        return SUCCESS;
    }
}

7.輔助類設計，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.最后也就是分頁頁面顯示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="0">    
    <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")[0].value;
                
            if(page > <s:property value="#request.pageBean.totalPage"/>)
            {
                alert("你輸入的頁數大於最大頁數，頁面將跳轉到首頁！");
                
                window.document.location.href = "personAction";
                
                return false;
            }
            
            return true;
        }
    
    </script>

  </head>
  
  <body>

    <h1><font color="blue">分頁查詢</font></h1><hr>
    
    <table border="1" align="center" bordercolor="yellow" width="50%">
    
        <tr>
            <th>序號</th>
            <th>姓名</th>
            <th>年齡</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="5">共<font color="red"><s:property value="#request.pageBean.totalPage"/></font>頁 </font>&nbsp;&nbsp;
        <font size="5">共<font color="red"><s:property value="#request.pageBean.allRows"/></font>條記錄</font><br><br>
        
        <s:if test="#request.pageBean.currentPage == 1">
            首頁&nbsp;&nbsp;&nbsp;上一頁
        </s:if>
        
        <s:else>
            <a href="personAction.action">首頁</a>
            &nbsp;&nbsp;&nbsp;
            <a href="personAction.action?page=<s:property value="#request.pageBean.currentPage - 1"/>">上一頁</a>
        </s:else>
        
        <s:if test="#request.pageBean.currentPage != #request.pageBean.totalPage">
            <a href="personAction.action?page=<s:property value="#request.pageBean.currentPage + 1"/>">下一頁</a>
            &nbsp;&nbsp;&nbsp;
            <a href="personAction.action?page=<s:property value="#request.pageBean.totalPage"/>">尾頁</a>
        </s:if>
        
        <s:else>
            下一頁&nbsp;&nbsp;&nbsp;尾頁
        </s:else>
    
    </center><br>
    
    <center>
        
        <form action="personAction" onsubmit="return validate();">
            <font size="4">跳轉至</font>
            <input type="text" size="2" name="page">頁
            <input type="submit" value="跳轉">
        </form>
        
    </center>
    
  </body>
</html>

至此，hibernate+struts2實現網頁分頁功能代碼部分就完畢了，像hibernate與struts的配置文件就不列出來了，那些都不是重點！

頁面效果如下: