【jsp 分页】mysql limit方式进行分页

项目结构示意图：

splitPage 

|-com.balfish.bean     Goods.java

|-com.balfish.dao       GoodsDao.java

|-com.balfish.servlet   MyServlet.java

|-com.balfish.util        DbConnection.java

 

|-WEB-INF　

　　|-lib　

　　　　|-jstl-1.2.jar

　　　　|-mysql-connector-java-5.1.5-bin.jar

　　|-page

　　　　|-myPage.jsp

　　|-web.xml

 

要点： 单例  分层  jstl  limit 

访问地址： http://localhost:8080/splitPage/getPage

 

 

 

Goods.java

package com.balfish.bean;



public class Goods {

    private int goodsId;

    private String goodsName;

    private float goodsPrice;

    public int getGoodsId() {

        return goodsId;

    }

    public void setGoodsId(int goodsId) {

        this.goodsId = goodsId;

    }

    public String getGoodsName() {

        return goodsName;

    }

    public void setGoodsName(String goodsName) {

        this.goodsName = goodsName;

    }

    public float getGoodsPrice() {

        return goodsPrice;

    }

    public void setGoodsPrice(float goodsPrice) {

        this.goodsPrice = goodsPrice;

    }

}

 

 

 

GoodsDao.java

package com.balfish.dao;



import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.ArrayList;



import com.balfish.bean.Goods;

import com.balfish.util.DbConnection;



public class GoodsDao {

    

    Connection conn;

    PreparedStatement psmt;

    ResultSet rs;

    

    int pageSize = 5; //每页显示5条数据

    

    public ResultSet executeQuery(String sql)throws Exception{

        

        conn =DbConnection.getConnection();

        psmt = conn.prepareStatement(sql);

        rs = psmt.executeQuery(sql);

        return rs;

    }

    

     //核心还是mysql的limit分页，然后暂存到内存中的ArrayList中

    public ArrayList<Goods> getGoodsList(int currentPage) throws Exception{

        ArrayList<Goods> GoodsList = new ArrayList<Goods>();

        int beginRecord = (currentPage -1) * pageSize;

        int endRecord = currentPage * pageSize;

        rs = executeQuery("select * from goods limit " + beginRecord + "," + endRecord);

    

        while(rs.next()){

            Goods goods = new Goods();

            goods.setGoodsId(rs.getInt(1));

            goods.setGoodsName(rs.getString(2));

            goods.setGoodsPrice(rs.getFloat(3));

            GoodsList.add(goods);

        }

        return GoodsList;

    } 

    

    public int getPageCount() throws Exception{

        int total = 0;

        int pageCount = 0;

        rs = executeQuery("select count(*) from goods");

    

        //得到分页的总页数，由于整数除法结果的取整形式，这里要用一点技巧进行处理

        if(rs.next()){

            total = rs.getInt(1);

            pageCount =(total -1) /pageSize +1;

        }

        return pageCount ;

    }     

}

 

 

 

 

MyServlet.java

package com.balfish.servlet;



import java.io.IOException;

import java.util.ArrayList;



import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;



import com.balfish.bean.Goods;

import com.balfish.dao.GoodsDao;



public class MyServlet extends HttpServlet{

    public void doGet(HttpServletRequest req , HttpServletResponse resp)

    throws ServletException,IOException{

        doPost(req, resp);

    }

    

    public void doPost(HttpServletRequest req , HttpServletResponse resp)

            throws ServletException,IOException{

        

        resp.setContentType("text/html");

        String tmpCurrentPage = req.getParameter("currentPage");

       

    //下面这几句挺无趣的，容易看的吃力，其实就是如果前面浏览过有页数标记则去读哪个页数，否则从第一页开始

        int currentPage = 1;

        if(tmpCurrentPage != null)

            currentPage = Integer.parseInt(tmpCurrentPage);

        

        GoodsDao goodsDao = new GoodsDao();

        try{

            ArrayList<Goods> GoodsList = goodsDao.getGoodsList(currentPage);

            //把数据信息放到req作用域中，

            req.setAttribute("GoodsList",GoodsList);

            req.setAttribute("currentPage",currentPage);

            req.setAttribute("pageCount",goodsDao.getPageCount());

            req.getRequestDispatcher("/WEB-INF/page/myPage.jsp").forward(req,resp);

            

        }catch(Exception e){

            e.printStackTrace();

        }

    }

    

    public void destroy(){

        super.destroy();

    }

    

    public void init(ServletConfig config) throws ServletException {

        super.init(config);

    }

}

 

 

 

DbConnection.java

package com.balfish.util;



import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.SQLException;



public class DbConnection {

    

    //抽象出单例，可作为模板

    private static Connection conn = null;

    private static String url = "jdbc:mysql://localhost/goods_test";

    private static String username ="root";

    private static String password ="";

    

    private DbConnection(){

  

    }

    

    public static Connection getConnection() throws Exception{

        Class.forName("com.mysql.jdbc.Driver");

        if(conn == null)

            conn =  DriverManager.getConnection(url,username,password);

        return conn;

    }

}

 

 

 

 

sql.txt

create database goods_test;

use goods_test;

create table goods(

    goodsId int,

    goodsName varchar(20),

    goodsPrice float

);





insert into goods values(1,'bag',68.8);

insert into goods values(2,'pen',10.0);

insert into goods values(3,'pencil',2.0);

insert into goods values(4,'mobile',968.8);

insert into goods values(5,'bag',68.8);

insert into goods values(6,'water',1.2);

 

 

 

myPage.jsp

    

<%@ page language ="java" import ="java.util.*" pageEncoding="utf-8" %>

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

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

    <head>

        <meta http-equiv ="content-type" content="text/html;charset=utf-8">

    </head>

    

    <body>

        <center>

            <c:if test = "${currentPage >= 1 }">

                <a href ="getPage?curentPage = 1">首页</a>

                <a href ="getPage?currentPage=${ currentPage-1}">上一页</a>

            </c:if>

            

            <c:if test="${currentPage == 1 }">

                  <a href="getPage?currentPage=${ currentPage+1}">下一页</a>

                  <a href="getPage?currentPage=${ pageCount}">尾页</a>

              </c:if>

              

              <table width="%80" border="1" height="56" >

                  <tr align ="center">

                      <td>商品编号</td>

                      <td>商品名称</td>

                      <td>商品价格</td>

                  </tr>

                  

                  <c:forEach var="goods" items="${GoodsList}">

<!--  上面的GoodsList后面多些了一个} 就报下面意想不到的错误,查了好久...所以下次jstl表达式使用时一定注意                   

javax.el.PropertyNotFoundException: Property 'goodsId' not found on type java.lang.String -->

                      <tr align="center">

                     <td>${goods.goodsId }</td>

                     <td>${goods.goodsName }</td>

                     <td>${goods.goodsPrice }</td>

                 </tr>

                  </c:forEach>

              </table>

        </center>

    </body>

</html>

 

 

 

 

 

web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>

<web-app xmlns="http://java.sun.com/xml/ns/javaee"

  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

  version="3.0"

  metadata-complete="true">





    <servlet>

        <servlet-name>test1</servlet-name>

        <servlet-class>com.balfish.servlet.MyServlet</servlet-class>

    </servlet>

    

    <servlet-mapping>

        <servlet-name>test1</servlet-name>

        <url-pattern>/getPage</url-pattern>

    </servlet-mapping>



</web-app>

 

 

 

运行结果：

地址栏http://localhost:8080/splitPage/getPage?currentPage=2（类似这样~）

 首页 上一页 下一页 尾页

商品编号	商品名称	商品价格
1	bag	68.8
2	pen	10.0
3	pencil	2.0
4	mobile	968.8
5	bag	68.8