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:
