使用hibernate和struts2实现分页功能的示例

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:

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