数据库分页 + jsp页面 完整代码案例
使用技术：
1）mysql数据库基础
2）C3P0连接池（开源框架）
3）dbUtils（第三方框架）
4）jsp基础
用到的第三方jar包：
C3P0连接池核心jar包：C3P0-0.9.1.0.jar
注意：C3P0使用配置文件方式实现，需在src目录下存放配置未见（c3p0-config.xml）
项目src包下 C3P0 配置问价格式如下（文件名：c3p0-config.xml）：
---------------------------------------------------------------------------------------------
<c3p0-config>
<!-- 以下是默认项 连接mysql的驱动 -->
<default-config>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/student</property>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="user">root</property>
<property name="password">123456</property>
<property name="initialPoolSize">3</property>
<property name="maxPoolSize">6</property>
<property name="maxIdleTime">1000</property>
</default-config>
<!-- 以下可以配置其他数据库的驱动 -->
<!-- <named-config name="oracle_config">
<property name="jdbcUrl">jdbc:mysql://localhost:3306/student</property>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="user">root</property>
<property name="password">root</property>
<property name="initialPoolSize">3</property>
<property name="maxPoolSize">6</property>
<property name="maxIdleTime">1000</property>
</named-config> -->
</c3p0-config>
-------------------------------------------------------------------------------------------
连接mysql数据的驱动jar包：mysql-connector-java-5.1.12-bin.jar
dbutils第三方jar包：commons-dbutils-1.6.jar
Jstl标签库的jar包：jstl-1.2.jar（若新建项目中没有带，则自行导入）
注意：使用javaee5.0的项目自动导入jstl支持jar包
实现效果
项目目录
项目描述及需求
项目图解
代码记录
untils包下工具类
-----------------------------JdbcUntils类代码如下（操作数据库的类）--------------------------------
package com.wxw.people.untils;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.apache.commons.dbutils.QueryRunner;
import org.junit.Test;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class JdbcUntils {
/*
* 1:初始化 C3P0 连接池
* */
private static DataSource dataSource;
static {
dataSource = new ComboPooledDataSource();
}
/*
* 2:创建DbUntils核心工具类对象
* */
public static QueryRunner getQueryRunner(){
// 创建QueryRunner对象，传入连接池对象
// 在创建QueryRunner对象的时候，如果传入了数据源对象；
// 那么在使用QueryRunner对象方法的时候，就不需要传入连接对象；
// 会自动从数据源中获取连接(不用关闭连接)
QueryRunner queryRunner = new QueryRunner(dataSource);
return queryRunner;
}
@Test
public void test(){
String sql = "insert into student(id,name,age,gender) values(?,?,?,?)";
for(int i = 8 ; i <= 100; i++){
if(i%2==0){
try {
getQueryRunner().update(sql, i,"Lucy" + i,i,"女" );
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else{
try {
getQueryRunner().update(sql, i,"Lucy" + i,i,"男" );
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
-----------------------------PageBean类代码如下（存储返回页数，查询到的分页数据等）--------------------------------
package com.wxw.people.untils;
import java.util.List;
public class PageBean<T> {
private int currentPage = 1; //当前页，默认显示第一页
private int pageCount = 8; //每页显示的行数（查询返回的行数），默认每页显示3行
private int totalCount ; //数据库表中的总记录数
private int totalPage; //总页数 = 总记录数 / 每页显示的行数（+1）
private List<T> list; //分页查询到的数据
//返回总页数
public int getTotalPage() {
//若总页数是奇数是页数增加的逻辑判断
if(totalCount % pageCount == 0){
totalPage = totalCount / pageCount;
}else{
totalPage = totalCount / pageCount +1;
}
return totalPage;
}
public int getCurrentPage() {
return currentPage;
}
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
public int getPageCount() {
return pageCount;
}
public void setPageCount(int pageCount) {
this.pageCount = pageCount;
}
public int getTotalCount() {
return totalCount;
}
public void setTotalCount(int totalCount) {
this.totalCount = totalCount;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
public List<T> getList() {
return list;
}
public void setList(List<T> list) {
this.list = list;
}
}
entity包下JavaBean类
-----------------------------Students类代码如下（JavaBean）--------------------------------package com.wxw.people.entity;
public class Students {
private int id;
private String name;
private int age;
private String gender;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Students [id=" + id + ", name=" + name + ", age=" + age
+ ", gender=" + gender + "]";
}
}
dao包下操作数据库的一个接口及实现类
-----------------------------操作数据库 IEmployeeDao 接口代码如下--------------------------------package com.wxw.people.dao;
import com.wxw.people.entity.Students;
import com.wxw.people.untils.PageBean;
/*
*
* 数据访问层，接口设计
* */
public interface IEmployeeDao {
/*
* 分页查询数据
* */
public void getAll(PageBean<Students> pageBean);
/*
* 查询总记录数
* */
public int getTotalCount();
}
-----------------------------操作数据库 EmployeeDao 实现类代码如下--------------------------------
package com.wxw.people.dao.impl;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import com.wxw.people.dao.IEmployeeDao;
import com.wxw.people.entity.Students;
import com.wxw.people.untils.JdbcUntils;
import com.wxw.people.untils.PageBean;
public class EmployeeDao implements IEmployeeDao {
@Override
public void getAll(PageBean<Students> pageBean) {
//查询总记录数； 并设置保存到pageBean对象中
int totalCount = getTotalCount();
pageBean.setTotalCount(totalCount);
/*
* 问题： jsp页面，如果当前页为首页，再点击上一页报错！
* 如果当前页为末页，再点下一页显示有问题！
* 解决：
* 1. 如果当前页 <= 0; 当前页设置当前页为1;
* 2. 如果当前页 > 最大页数； 当前页设置为最大页数
*/
if(pageBean.getCurrentPage() <= 0){
pageBean.setCurrentPage(1);
}else if(pageBean.getCurrentPage() > pageBean.getTotalPage()){
pageBean.setCurrentPage(pageBean.getTotalPage());
}
//获取当前页：计算查询的起始行、返回行数
int currentPage = pageBean.getCurrentPage();
int index = (currentPage - 1)*pageBean.getPageCount();
int count = pageBean.getPageCount();
String sql = "select * from student limit ?,?";
QueryRunner queryRunner = JdbcUntils.getQueryRunner();
try {
List<Students> list = queryRunner.query(sql, new BeanListHandler<Students>(Students.class),index,count);
pageBean.setList(list);
} catch (SQLException e) {
e.printStackTrace();
}
}
public int getTotalCount() {
String sql = "select count(*) from student";
try {
Long count = JdbcUntils.getQueryRunner().query(sql, new ScalarHandler<Long>());
return count.intValue();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
service包下操作业务逻辑的一个接口及实现类
-----------------------------操作业务逻辑 IEmployeeService 接口代码如下--------------------------------
package com.wxw.people.service;
import com.wxw.people.entity.Students;
import com.wxw.people.untils.PageBean;
public interface IEmployeeService {
public void getAll(PageBean<Students> pb);
}
-----------------------------操作业务逻辑 EmployeeService 实现类代码如下--------------------------------
package cn.itcast.service.impl;
import cn.itcast.dao.IEmployeeDao;
import cn.itcast.dao.impl.EmployeeDao;
import cn.itcast.entity.Employee;
import cn.itcast.service.IEmployeeService;
import cn.itcast.utils.PageBean;
/**
* 3. 业务逻辑层，实现
* @author Jie.Yuan
*
*/
public class EmployeeService implements IEmployeeService {
// 创建Dao实例
private IEmployeeDao employeeDao = new EmployeeDao();
@Override
public void getAll(PageBean<Employee> pb) {
try {
employeeDao.getAll(pb);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
servlet包下接收请求数据的servlet类
-----------------------------接收请求 参数 IndexServlet 类代码如下--------------------------------
package com.wxw.people.servlet;import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.wxw.people.entity.Students;
import com.wxw.people.service.IEmployeeService;
import com.wxw.people.service.impl.EmployeeService;
import com.wxw.people.untils.PageBean;
public class IndexServlet extends HttpServlet {
private IEmployeeService service = new EmployeeService();
private String uri;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
try {
//获取“当前页”参数(第一次访问时当前页为null)
String currPage = req.getParameter("currentPage");
//判断 第一次是设置默认值
if(currPage == null || "".equals(currPage)){
currPage = "1";
}
//转换 从jsp获取的都是字符串型的 需转换为整形才能保存到javaBean中
int currentPage = Integer.parseInt(currPage);
PageBean<Students> pb = new PageBean<Students>();
pb.setCurrentPage(currentPage);
//调用service层
service.getAll(pb);
//保存域对象
req.setAttribute("pageBean", pb);
uri = "/WEB-INF/index.jsp";
} catch (NumberFormatException e) {
e.printStackTrace();
uri = "/error/error.jsp";
}
//跳转
req.getRequestDispatcher(uri).forward(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
}
网页端向用户展现的JSP页面
-----------------------------JSP页面代码如下--------------------------------
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>分页</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<table border="1" width="80%" align="center" cellpadding="5" cellspacing="0">
<tr>
<td>编号</td>
<td>姓名</td>
<td>年龄</td>
<td>性别</td>
</tr>
<c:choose>
<c:when test="${not empty requestScope.pageBean.list }">
<c:forEach var="stu" items="${requestScope.pageBean.list }" varStatus="vs">
<tr>
<td>${stu.id }</td>
<td>${stu.name }</td>
<td>${stu.age }</td>
<td>${stu.gender }</td>
</tr>
</c:forEach>
</c:when>
<c:otherwise>
<tr>
<td colspan="8">对不起，没有你要找的数据</td>
</tr>
</c:otherwise>
</c:choose>
<tr>
<td colspan="8" align="center">
<a href="${pageContext.request.contextPath }/index?currentPage=1">首页</a>
<a href="${pageContext.request.contextPath }/index?currentPage=${requestScope.pageBean.currentPage - 1}">上一页</a>
<a href="${pageContext.request.contextPath }/index?currentPage=${requestScope.pageBean.currentPage + 1}">下一页</a>
<a href="${pageContext.request.contextPath }/index?currentPage=${requestScope.pageBean.totalPage}">末页</a>
</td>
</tr>
</table>
</body>
</html>