使用hibernate和struts2实现分页功能的示例

2019-11-26 13:19:19

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想着每天能学个新东西，今天准备了这个hibernate+struts2实现页面的分页功能，以下是源代码。

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 = 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 == 0)? (allRows / pageSize): (allRows / pageSize) + 1;        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 - 1);        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 == 0)? 1: 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(5, 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="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="1" 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="5">共<font color="red"><s:property value="#request.pageBean.totalPage"/></font>页 </font>      <font size="5">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   上一页    </s:if>        <s:else>      <a href="personAction.action">首页</a>               <a href="personAction.action?page=<s:property value="#request.pageBean.currentPage - 1"/>">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 + 1"/>">下一页</a>               <a href="personAction.action?page=<s:property value="#request.pageBean.totalPage"/>">尾页</a>    </s:if>        <s:else>      下一页   尾页    </s:else>    </center><br>    <center>        <form action="personAction" onsubmit="return validate();">      <font size="4">跳转至</font>      <input type="text" size="2" 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: