一：运行效果

运行之后如上图👆所示。

所包含的功能有： 首页、尾页、上一页、下一页、当前的页码和总页码统计等。

至于关于分页的其他功能，如控制每一页显示几条数据、跳转到第几页等，有待后续更新...

二：代码详解

（1）index.jsp

首页发起请求。侧重功能实现，没做样式（可自行设计）。

<%--Created by IntelliJ IDEA.User: AdminSunDate: 2023/6/12Time: 15:44To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html><head><title>首页</title></head><body><h1>欢迎使用</h1><a href="/RoomServlet">分页查询展示</a></body>
</html>

（2）PageBean

分页工具类:

package cn.shq.util;import java.util.List;public class PageBean {private Integer curPage;//当前页码private Integer pageSize;//每一页显示的条数private List datas; //每一页要显示的数据private Integer firstPage;//首页private Integer prevPage;//上一页private Integer nextPage;//下一页private Integer lastPage;//尾页private  Integer totalCount;//数据总条数private  Integer totalPages; //总页码public PageBean() {}/*   构造方法*/public PageBean(Integer curPage, Integer pageSize, List datas, Integer totalCount) {//初始化各个属性this.curPage = curPage;this.pageSize = pageSize;this.datas = datas;this.totalCount = totalCount;//计算出来其他的属性=====也算作初始化//计算总页码/**    总页码  = 总条数 %  pageSize  ? 整除   则 总条数/pageSize*                                   有余数   总条数/pageSize+1* */this.totalPages=this.totalCount%this.pageSize==0?this.totalCount/this.pageSize:this.totalCount/this.pageSize+1;//   意思：   ↓↓↓↓/* if(totalCount%pageSize==0){this.totalPages=totalCount/pageSize;}else{this.totalPages=totalCount/pageSize+1;}*/this.firstPage=1;this.prevPage=this.curPage-1;this.nextPage=this.curPage+1;this.lastPage=this.totalPages;//对于超出范围的，加以限定//如果第一次访问的时候，if(curPage==null||curPage<1) curPage=1;//总页码if(this.totalPages==0) this.totalPages=1;//对于 上一页   当显示的页面为第一页的时候，不再递减if(prevPage<=0) this.prevPage=1;//对于下一页  最后一页的时候，下一页 停留在最后一页if(nextPage>=this.totalPages) this.nextPage=this.totalPages;}public Integer getCurPage() {return curPage;}public void setCurPage(Integer curPage) {this.curPage = curPage;}public Integer getPageSize() {return pageSize;}public void setPageSize(Integer pageSize) {this.pageSize = pageSize;}public List getDatas() {return datas;}public void setDatas(List datas) {this.datas = datas;}public Integer getFirstPage() {return firstPage;}public void setFirstPage(Integer firstPage) {this.firstPage = firstPage;}public Integer getPrevPage() {return prevPage;}public void setPrevPage(Integer prevPage) {this.prevPage = prevPage;}public Integer getNextPage() {return nextPage;}public void setNextPage(Integer nextPage) {this.nextPage = nextPage;}public Integer getLastPage() {return lastPage;}public void setLastPage(Integer lastPage) {this.lastPage = lastPage;}public Integer getTotalCount() {return totalCount;}public void setTotalCount(Integer totalCount) {this.totalCount = totalCount;}public Integer getTotalPages() {return totalPages;}public void setTotalPages(Integer totalPages) {this.totalPages = totalPages;}}

（3）Servlet

控制器类：

package cn.shq.controller;import cn.shq.dao.RoomDao;
import cn.shq.dao.impl.RoomDaoImp;
import cn.shq.util.PageBean;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet(name = "RoomServlet", value = "/RoomServlet")
public class RoomServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request,response);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {RoomDao rm=new RoomDaoImp();String pageParam = req.getParameter("curPage");if (pageParam == null) pageParam = "1";if (pageParam == "") pageParam = "1";int curPage = Integer.parseInt(pageParam);//每一页显示的条数， 从页面下拉框获取String psize=req.getParameter("pageSize");if (psize == null) psize = "3";int pageSize = Integer.parseInt(psize);//调用dao，执行查询PageBean pageBean = rm.selByPage(curPage, pageSize);req.setAttribute("pager", pageBean);req.getRequestDispatcher("/admin/showRoom.jsp").forward(req, response);}}

（4）DAO层

本案例中Servlet直接访问DAO层调用方法。

package cn.shq.dao.impl;import cn.shq.dao.RoomDao;
import cn.shq.util.BaseDao;
import cn.shq.util.PageBean;import java.util.List;
import java.util.Map;public class RoomDaoImp implements RoomDao {@Overridepublic PageBean selByPage(int curPage, int pageSize) {String sql="select r.rNum,r.rStatus,rs.roomstatus,rt.typeName,r.rPrice,r.rPhone,r.rPic \n" +"from room r,roomstatus rs,roomtype rt\n" +"where r.rType=rt.tid and r.rStatus=rs.sid\n" +"LIMIT ?,?";int startIndex=pageSize	* (curPage-1);List<Map<String, Object>> list = BaseDao.executeQuery(sql, startIndex, pageSize);sql="select count(*) pageNum from room";Long pageNum = (Long) BaseDao.executeQuery(sql).get(0).get("pageNum");PageBean pageBean = new PageBean(curPage,pageSize,list,pageNum.intValue());pageBean.setDatas(list);pageBean.setTotalCount(pageNum.intValue());return pageBean;}
}

（5）BaseDao

访问数据库所用的工具类

package cn.shq.util;import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class BaseDao {protected static Connection conn = null;protected static PreparedStatement pstm = null;protected static ResultSet rs = null;private static String driver="com.mysql.jdbc.Driver";private static String url="jdbc:mysql://localhost:3306/bbs_xdy?useSSL=true";private static String username="root";private static String password="123456";private static Connection getConn(){try {Class.forName(driver);Connection connection = DriverManager.getConnection(url,username,password);return connection;} catch (Exception e) {e.printStackTrace();}return null;}/** 通用关闭* */public static void closeAll(Connection conn,PreparedStatement pstm,ResultSet rs) {try {if (rs != null) {rs.close();}if (pstm != null) {pstm.close();}if (conn != null) {conn.close();}} catch (Exception e) {e.printStackTrace();}}/** 增删改* */public static int executeUpdate(String sql, Object... obj) {try {conn = getConn();pstm = conn.prepareStatement(sql);setParam(obj);int num = pstm.executeUpdate();return num;} catch (Exception e) {e.printStackTrace();} finally {closeAll(conn,pstm,rs);}return 0;}/** 解决占位符参数的问题* */private static void setParam(Object... obj) {if (obj != null) {for (int i = 0; i < obj.length; i++) {try {pstm.setObject(i + 1, obj[i]);} catch (Exception e) {e.printStackTrace();}}}}/** 通用查询* */public static List<Map<String, Object>> executeQuery(String sql, Object... obj) {List<Map<String, Object>> list = new ArrayList();try {conn = getConn();pstm = conn.prepareStatement(sql);setParam(obj);rs = pstm.executeQuery();ResultSetMetaData rd = rs.getMetaData();int count = rd.getColumnCount();while (rs.next()) {Map<String, Object> map = new HashMap();for (int i = 0; i < count; i++) {map.put(rd.getColumnName(i + 1), rs.getObject(i + 1));}list.add(map);}} catch (SQLException e) {e.printStackTrace();} finally {closeAll(conn,pstm,rs);}return list;}
}

（6）JSP

展示数据的页面。

<%--Created by IntelliJ IDEA.User: AdminSun Date: 2020/12/08Time: 10:49To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<head><title>住房管理</title><link rel="stylesheet" href="../bootstrap/bootstrap-3.3.7-dist/css/bootstrap.css"><script src="../js/jquery-3.4.1.min.js"></script><script src="../bootstrap/bootstrap-3.3.7-dist/js/bootstrap.js"></script><style>*{margin: 20px auto;}</style>
</head>
<body><%--显示数据的表格--%><table class="table table-hover table-bordered"><thead><tr><th>序号</th><th>房号</th><th>房间图片</th><th>房间状态</th><th>房间类型</th><th>房间价格（元）</th><th>房间电话</th></tr></thead><tbody><c:if test="${empty pager.datas}"><script>alert("没有数据");</script></c:if><c:if test="${ not empty pager.datas}"><c:forEach items="${pager.datas}" var="room" varStatus="s"><tr><td>${s.count}</td><td>${room.rNum}</td><td><img src="${room.rPic}" /></td><td>${room.roomstatus}</td><td>${room.typeName}</td><td>${room.rPrice}</td><td>${room.rPhone}</td></tr></c:forEach></c:if></tbody></table><%--分页控制--%><ul class="pagination"><li><a href="/RoomServlet?op=selPage&&curPage=${pager.firstPage}">首页</a></li><li><a href="/RoomServlet?op=selPage&&curPage=${pager.prevPage}">上一页</a></li><li><a href="/RoomServlet?op=selPage&&curPage=${pager.nextPage}">下一页</a></li><li><a href="/RoomServlet?op=selPage&&curPage=${pager.lastPage}">尾页</a></li><li><a href="#">当前第 ${pager.curPage}页/共${pager.totalPages}页</a></li></ul>
</body>
</html>

该页面显示数据使用了JSTL标签库。

所以需要注意的是：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

（7）所需数据表

仅展示主要表。其他表需自行创建。

（8）案例项目结构

案例结构描述
src	写Java源代码的根目录。
web/admin	展示数据的JSP页面
web/bootstrap：	案例中所需要的Bootstrap样式表和脚本库
web/img	存放案例所需图片
web/js	案例中jQuery所用库
web/WEB-INF/lib	案例所用jar包（连接MySQL数据库和JSTL标签库）