使用servlet和jsp实现页面信息的分页展示,数据从数据库中查询出来(首页,上一页,下一页,末页)
一 最终效果展示1.数据从首页开始展示,所以没有前一页
2.第二页时包含前一页和后一页
3.末页时不包含后一页
4.也可以选择每一页要展示的数据条数
二 代码1.先创建一个用来实现分页的实体类
package com.briup.model;import java.util.List;/** * 用来进行页面分页,切换页数的实体类 * @author MECHREVO * */public class PageInfo<T> {private int pageSize = 5; //每页显示的数据条数private int total; //总记录数private int currentPage = 1; //当前页码private int pages; //总页数。private int prePage; //前一页private int nextPage; //后一页private int firstPage = 1; //首页private int lastPage; //末页private boolean hasPrePage; private boolean hasNextPage;private List<T> datas; //当前页要显示的所有数据。public PageInfo(int total,int pageSize,int currentPage,List<T> datas) {this.total = total;this.pageSize = pageSize;this.currentPage = currentPage;this.datas = datas;//判断总页数,如果取余等于0则不加一,如果不等于则加一this.pages = total%pageSize==0?total/pageSize:total/pageSize+1;this.prePage = currentPage<=1?currentPage:currentPage-1;this.nextPage = currentPage>=pages?currentPage:currentPage+1;this.lastPage = pages;this.hasNextPage = currentPage<pages;this.hasPrePage = currentPage>1;}public int getPageSize() {return pageSize;}public int getTotal() {return total;}public int getCurrentPage() {return currentPage;}public int getPages() {return pages;}public int getPrePage() {return prePage;}public int getNextPage() {return nextPage;}public int getFirstPage() {return firstPage;}public int getLastPage() {return lastPage;}public boolean isHasPrePage() {return hasPrePage;}public boolean isHasNextPage() {return hasNextPage;}public List<T> getDatas() {return datas;}}2.展示信息的jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="java.sun/jsp/jstl/core" %><!DOCTYPE html><html><head><meta charset="UTF-8"><!-- base设置文件相对的路径,可以避免页面跳转找不到的错误 --><base href="${pageContext.request.contextPath}/"><title>区域信息管理</title><link style="text/css" rel="stylesheet" href="css/main.css"></head><body> <div class="main"> <div class="head"> <h1>企业信息管理系统</h1> </div> <div class="content"> <div class="left"> <ul> <li><a href="region/allregion.do">区域信息管理</a></li> <li><a href="depart/depart.html">部门信息管理</a></li> <li><a href="emp/emp.html">员工信息管理</a></li> </ul> </div> <div class="rigth"> <div class = "search"> <span> <input type="text" placeholder="请输入区域名称"> <button>检索</button> <button onclick="javascript:window.location.href='region/addRegion.html'">添加</button> </span> </div> <table> <thead> <tr> <th>区域编号</th> <th>区域名称</th> <th>操作</th> </tr> </thead> <tbody> <c:forEach var="region" items="${requestScope.pageInfo.datas }" varStatus="s"> <c:if test="${(s.index+1)%2==0 }"> <tr class="odd"> </c:if> <c:if test="${(s.index+1)%2!=0 }"> <tr> </c:if> <td>${region.id }</td> <td>${region.name }</td> <td><button>编辑</button> <button>删除</button></td> </tr> </c:forEach> </tbody> <tfoot> <tr> <td colspan="3" align="right"> <select name="pageSize" onchange="changeSize(this.value)"> <option value="5">5</option> <option value="10">10</option> <option value="15">15</option> <option value="20">20</option> </select> <!-- 设置后用于更改默认的展示条数 --> <script type="text/javascript"> pageSize = ${pageInfo.pageSize}; options = document.getElementsByTagName("option"); for(var i=0;i<options.length;i++){ if(options[i].value==pageSize){ options[i].selected='selected'; } } </script> <span><a href="region/allregion.do?currentPage=1&pageSize=${pageInfo.pageSize }">首 页</a></span> <!-- 判断有没有前一页 --> <c:if test="${ pageInfo.hasPrePage}"> <span><a href="region/allregion.do?currentPage=${pageInfo.prePage }&pageSize=${pageInfo.pageSize }">前一页</a></span> </c:if> <!-- 判断有没有后一页 --> <c:if test="${pageInfo.hasNextPage}"> <span><a href="region/allregion.do?currentPage=${pageInfo.nextPage }&pageSize=${pageInfo.pageSize }">后一页</a></span> </c:if> <span><a href="region/allregion.do?currentPage=${pageInfo.pages }&pageSize=${pageInfo.pageSize }">末 页</a></span> 共${pageInfo.total }条记录${pageInfo.pages }页 </td> </tr> </tfoot> </table> </div> </div> <div style="clear: both;"></div> <div class="footer"> 本系统最终解释权为我所有。 </div> </div></body><script type="text/javascript"> function changeSize(pageSize){ window.location.href="allregion.do?pageSize="+pageSize }</script></html>3.创建一个java类,书写SQL语句实现查询
package com.briup.dao.impl;import java.math.BigDecimal;import java.sql.Connection;import java.sql.SQLException;import java.util.List;import org.apachemons.dbutils.QueryRunner;import org.apachemons.dbutils.handlers.BeanListHandler;import org.apachemons.dbutils.handlers.ScalarHandler;import com.briupmon.util.DBUtils;import com.briup.dao.IRegionDao;import com.briup.model.Region;public class RegionDaoImpl implements IRegionDao{QueryRunner qr = new QueryRunner();//查询数据总数public int count() {try(Connection conn = DBUtils.getConnection();) {return qr.query(conn, "select count(*) from s_region",new ScalarHandler<BigDecimal>(1)).intValue();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();throw new RuntimeException(e);}}public List<Region> findByPage(int currentPage,int pageSize){//分页代码的核心SQL语句利伪列rownum来实现try(Connection conn = DBUtils.getConnection();) {List<Region> list = qr.query(conn, "select id,name from "+"(select id,name,rownum r "+"from s_region) region "+"where r between ? and ?",new BeanListHandler<Region>(Region.class),(currentPage-1)*pageSize+1,currentPage*pageSize);System.out.println("list:"+list);return list;} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();throw new RuntimeException(e);}}}4.创建一个类调用上面的方法来产生一个分页的实体对象
package com.briup.service.impl;import java.util.List;import com.briupmon.util.BeanFactory;import com.briup.dao.IRegionDao;import com.briup.model.PageInfo;import com.briup.model.Region;import com.briup.service.IRegionService;public class RegionServiceImpl implements IRegionService{IRegionDao dao = (IRegionDao) BeanFactory.getBean(BeanFactory.GERION_DAO);public PageInfo<Region> findByPage(int currentPage,int pageSize){int total = dao.count();List<Region> list = dao.findByPage(currentPage, pageSize);System.out.println("------------------"+list);return new PageInfo<Region>(total, pageSize, currentPage, list);}}5.写一个servlet实现页面信息的分页展示
package com.briup.web.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.briupmon.util.BeanFactory;import com.briup.model.PageInfo;import com.briup.model.Region;import com.briup.service.IRegionService;//多一个region/,是为了后面可以过滤region/*@WebServlet("/region/allregion.do")public class AllRegionServlet2 extends HttpServlet{private static final long serialVersionUID = 1L;IRegionService service = (IRegionService) BeanFactory.getBean(BeanFactory.GERION_SERVICE);@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String pageSizeStr = req.getParameter("pageSize");String currentPageStr = req.getParameter("currentPage");//先给一个默认值,用来定义第一次加载显示的标准int pageSize = 5;int currentPage = 1;//判断不为null 或者 去首尾空格后不为""if(pageSizeStr!=null && !"".equals(pageSizeStr.trim())) {pageSize = Integer.parseInt(pageSizeStr);}if(currentPageStr!=null && !"".equals(currentPageStr.trim())) {currentPage = Integer.parseInt(currentPageStr);}try {PageInfo<Region> pageInfo = service.findByPage(currentPage, pageSize);req.setAttribute("pageInfo", pageInfo);req.getRequestDispatcher("/region/region.jsp").forward(req, resp);;} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}}6.上面用到的接口和产生对象的java类
package com.briup.dao;import java.util.List;import com.briup.model.Region;public interface IRegionDao {int count();List<Region> findByPage(int currentPage,int pageSize);} package com.briup.service;import com.briup.model.PageInfo;import com.briup.model.Region;public interface IRegionService {PageInfo<Region> findByPage(int currentPage,int pageSize);}产生对象的类,作用是用来解耦合
1.先写一个bean.properties文件用来保存要产生对象的权限类名
regionDao=com.briup.dao.impl.RegionDaoImpl regionService=com.briup.service.impl.RegionServiceImpl
2.写一个java类来解析这个文件,并产生对应的对象
package com.briupmon.util;import java.io.IOException;import java.util.Properties;public class BeanFactory {public final static String GERION_DAO = "regionDao";public final static String GERION_SERVICE = "regionService";private static Properties props = new Properties();static {try {props.load(BeanFactory.class.getResourceAsStream("/bean.properties"));} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();throw new RuntimeException(e);}}public static Object getBean(String name) {/*if(name.equals(GERION_DAO)) {return new RegionDaoImpl();}else if(name.equals(GERION_SERVICE)){return new RegionServiceImpl();}else {return null;}*/String clsName = props.getProperty(name);try {return Class.forName(clsName).newInstance();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();throw new RuntimeException(e);}}}
使用servlet和jsp实现页面信息的分页展示,数据从数据库中查询出来(首页,上一页,下一页,末页)