MySQL分页查询
Posted 囧雪
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了MySQL分页查询相关的知识，希望对你有一定的参考价值。
一、在Dao类中写两种方法：获得总页数和指定页的数据
获得总页数
public int getPageCount(int pageSize) throws Exception{ try { conn=DBConnection.getConnection(); String sql="select count(*) from car"; stat=conn.prepareStatement(sql); rs=stat.executeQuery(); rs.next(); int rowsCount=rs.getInt(1); int pageCount=(int)Math.ceil(1.0*rowsCount/pageSize);//算出总共需要多少页 return pageCount; } finally{ conn.close(); }
获得指定页的数据
public ArrayList<Car> getPageCar(int pageNo,int pageSize) throws Exception{//两个形参分别为当前页，每页有多少行 ArrayList<Car> list=new ArrayList<Car>(); try { conn=DBConnection.getConnection(); String sql="select * from car limit ?,?"; stat=conn.prepareStatement(sql); stat.setInt(1, (pageNo-1)*pageSize);距离这一页的第一行数据，其前面有多少行数据 stat.setInt(2, pageSize);//每页有多少行 rs=stat.executeQuery(); while(rs.next()){ Car data=new Car(); data.setCode(rs.getString(1)); data.setName(rs.getString(2)); data.setBrand(rs.getString(3)); data.setTime(rs.getDate(4)); data.setOil(rs.getDouble(5)); data.setPowers(rs.getInt(6)); data.setExhaust(rs.getInt(7)); data.setPrice(rs.getDouble(8)); data.setImage(rs.getString(8)); list.add(data); } } finally{ conn.close(); } return list; }
二、servlet处理数据
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取参数 int pageNo=1; String s=request.getParameter("pgno"); if(s!=null){ pageNo=Integer.parseInt(s); } //处理数据 try { int pageCount=new CarDao().getPageCount(PAGESIZE);//获得总页数 ArrayList<Car> list=new CarDao().getPageCar(pageNo, PAGESIZE);//获得指定页数据 int currentPage=pageNo; request.setAttribute("currentPage", currentPage); request.setAttribute("pageCount", pageCount); request.setAttribute("cars", list); int pagePrev=pageNo>1?pageNo-1:1;//上一页 int pageNext=pageNo<pageCount?pageNo+1:pageCount;//下一页 request.setAttribute("pageNow", pageNo); request.setAttribute("pagePrev", pagePrev); request.setAttribute("pageNext", pageNext); } catch (Exception e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } //跳转 request.getRequestDispatcher("home.jsp").forward(request, response); }
三、在jsp页面输出
<%@page import="com.itnba.maya.bean.Car"%> <%@page import="java.util.ArrayList"%> <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Insert title here</title> <script> function aaa(){ document.getElementById("f1").submit(); } </script> </head> <body> <h1>汽车分页</h1> <c:forEach items="${cars }" var="c"> <div> <span style="width:100px;display:inline-block;">${c.code }</span> <span style="width:300px;display:inline-block;">${c.name }</span> </div> </c:forEach> <!--下面是分页链接 --> <a href="show?pgno=1">首页</a> <a href="show?pgno=${pagePrev }">上一页</a> <c:forEach begin="1" end="${pageCount }" var="i"> <a href="show?pgno=${i }">${i }</a> </c:forEach> <a href="show?pgno=${pageNext }">下一页</a> <a href="show?pgno=${pageCount }">尾页</a> <form id="f1" method="get" action="show"> <select name="pgno" onchange="aaa()"> <c:forEach begin="1" end="${pageCount }" var="i"> <c:choose> <c:when test="${pageNow == i }"> <option value="${i }" selected="selected" >${i }</option> </c:when> <c:otherwise> <option value="${i }">${i }</option> </c:otherwise> </c:choose> </c:forEach> </select> </form> </body> </html>
运行结果：
以上是关于MySQL分页查询的主要内容，如果未能解决你的问题，请参考以下文章