案例项目
目录
采用Model1（JSP+JavaBean）来实现浏览商品记录的开发步骤：
用到JavaSE部分的JDBC技术，JavaEE部分的cookie保存浏览记录，JSP+JavaBean的分层架构思想
实现DBHelper类，来获得数据库连接等
MySQL数据库创建
数据库名:mydatabase；数据库密码admin
语句:
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for items
-- ----------------------------
DROP TABLE IF EXISTS `items`;
CREATE TABLE `items` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(50) default NULL,
`city` varchar(50) default NULL,
`price` int(11) default NULL,
`number` int(11) default NULL,
`picture` varchar(500) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of items
-- ----------------------------
INSERT INTO `items` VALUES ('1', '沃特篮球鞋', '佛山', '180', '500', '001.jpg');
INSERT INTO `items` VALUES ('2', '安踏运动鞋', '福州', '120', '800', '002.jpg');
INSERT INTO `items` VALUES ('3', '耐克运动鞋', '广州', '500', '1000', '003.jpg');
INSERT INTO `items` VALUES ('4', '阿迪达斯T血衫', '上海', '388', '600', '004.jpg');
INSERT INTO `items` VALUES ('5', '李宁文化衫', '广州', '180', '900', '005.jpg');
INSERT INTO `items` VALUES ('6', '小米3', '北京', '1999', '3000', '006.jpg');
INSERT INTO `items` VALUES ('7', '小米2S', '北京', '1299', '1000', '007.jpg');
INSERT INTO `items` VALUES ('8', 'thinkpad笔记本', '北京', '6999', '500', '008.jpg');
INSERT INTO `items` VALUES ('9', 'dell笔记本', '北京', '3999', '500', '009.jpg');
INSERT INTO `items` VALUES ('10', 'ipad5', '北京', '5999', '500', '010.jpg');
DBHelper类
package util;
import java.sql.Connection;
import java.sql.DriverManager;
public class DBHelper {
private static final String driver="com.mysql.cj.jdbc.Driver";//数据库驱动
//连接数据库的URL地址
private static final String url="jdbc:mysql://localhost:3306/mydatabase?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
private static final String username="root";//数据库的用户名
private static final String password="admin";//数据库的密码
private static Connection conn=null;
//静态代码块负责加载驱动
static {
try {
Class.forName(driver);
}catch (Exception ex) {
ex.printStackTrace();
}
}
//单例模式返回数据库连接对象
public static Connection getConnection() throws Exception{
if(conn==null) {
conn= DriverManager.getConnection(url, username, password);
return conn;
}
return conn;
}
public static void main(String[] args) {
try {
Connection conn=DBHelper.getConnection();
if(conn!=null) {
System.out.println("数据库连接正常");
}
else {
System.out.println("数据库连接异常");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
注:
driver="com.mysql.cj.jdbc.Driver";
url="jdbc:mysql://localhost:3306/mydatabase?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
创建实体类，对应了数据库中的表
创建完实体类后-点击source-点击format格式化代码
package entity;
//商品类
public class Items {
private int id;// 商品编号
private String name;// 商品名称
private String city;// 产地
private int price;// 商品价格
private int number;// 商品数量
private String picture;// 商品图片
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 String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
public String getPicture() {
return picture;
}
public void setPicture(String picture) {
this.picture = picture;
}
}
创建业务逻辑类（DAO）
注意在写代码时，尽可能引进一些SQL类的包
package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import entity.Items;
import util.DBHelper;
//商品的业务逻辑类
public class ItemsDAO {
// 获得所有的商品信息
public ArrayList<Items> getAllItems() {
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
ArrayList<Items> list = new ArrayList<Items>();// 商品集合
try {
conn = DBHelper.getConnection();
String sql = "select *from Items";// SQL语句
stmt = conn.prepareStatement(sql);
rs = stmt.executeQuery();
while (rs.next()) {
Items item = new Items();
item.setId(rs.getInt("id"));
item.setCity(rs.getString("city"));
item.setName(rs.getString("name"));
item.setNumber(rs.getInt("number"));
item.setPrice(rs.getInt("price"));
item.setPicture(rs.getString("picture"));
list.add(item);// 把一个商品加入集合
}
return list;// 返回集合
} catch (Exception ex) {
ex.printStackTrace();
return null;
} finally {
// 释放数据集对象
if (rs != null) {
try {
rs.close();
rs = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
// 释放语句对象
if (stmt != null) {
try {
stmt.close();
stmt = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
// 根据商品编号获取商品资料
public Items getItemsById(int id) {
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = DBHelper.getConnection();
String sql = "select *from items where id=?";// SQL语句
stmt = conn.prepareStatement(sql);
stmt .setInt(1, id);
rs = stmt.executeQuery();
if (rs.next()) {
Items item = new Items();
item.setId(rs.getInt("id"));
item.setCity(rs.getString("city"));
item.setName(rs.getString("name"));
item.setNumber(rs.getInt("number"));
item.setPrice(rs.getInt("price"));
item.setPicture(rs.getString("picture"));
return item;
} else {
return null;
}
} catch (Exception ex) {
ex.printStackTrace();
return null;
} finally {
// 释放数据集对象
if (rs != null) {
try {
rs.close();
rs = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
// 释放语句对象
if (stmt != null) {
try {
stmt.close();
stmt = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
// 获取最近浏览的前五条商品信息
public ArrayList<Items> getViewList(String list){
ArrayList<Items> itemlist=new ArrayList<Items>();
int iCount = 5;//每次返回前五条记录
if(list!=null&&list.length()>0) {
String[] arr=list.split(",");
//如果商品记录大于或等于五条
if(arr.length>=5) {
for(int i=arr.length-1;i>=arr.length-iCount-1;i--) {
itemlist.add(getItemsById(Integer.parseInt(arr[i])));
}
}
else {
for(int i=arr.length-1;i>=0;i--) {
itemlist.add(getItemsById(Integer.parseInt(arr[i])));
}
}
return itemlist;
}
else {
return null;
}
}
}
注:如何把浏览记录保存在cookie中?
因为商品编号是唯一的，我们可以获取商品的编号，自然而然可以获取商品的信息。那么用户在每一次点击商品的详情的时候，他会把商品的编号传给details.jsp页面，那么我们可以想办法在details.jsp页面当中把传过来的商品编号给它保存在一个字符串当中。
主要思路：
把每次浏览的商品编号保存在字符串中，编号和编号之间用分隔符分隔，每次取出前五条记录。（把字符串保存在cookie当中，每次只要在cookie中读取这个字符串就可以了。把这个字符串通过分隔符转换成字符串数组，数组中的每个元素实际上就是商品编号）
创建页面层
Details.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8" %>
<%@ page import="entity.Items"%>
<%@ page import="dao.ItemsDAO"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'details.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<style type="text/css">
div{
float:left;
margin-left: 30px;
margin-right:30px;
margin-top: 5px;
margin-bottom: 5px;
}
div dd{
margin:0px;
font-size:10pt;
}
div dd.dd_name
{
color:blue;
}
div dd.dd_city
{
color:#000;
}
</style>
</head>
<body>
<h1>商品详情</h1>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<!-- 商品详情 -->
<%
ItemsDAO itemDao = new ItemsDAO();
Items item = itemDao.getItemsById(Integer.parseInt(request.getParameter("id")));
if(item!=null)
{
%>
<td width="70%" valign="top">
<table>
<tr>
<td rowspan="4"><img src="images/<%=item.getPicture()%>" width="200" height="160"/></td>
</tr>
<tr>
<td><B><%=item.getName() %></B></td>
</tr>
<tr>
<td>产地：<%=item.getCity()%></td>
</tr>
<tr>
<td>价格：<%=item.getPrice() %>￥</td>
</tr>
</table>
</td>
<%
}
%>
<%
String list ="";
//从客户端获得Cookies集合
Cookie[] cookies = request.getCookies();
//遍历这个Cookies集合
if(cookies!=null&&cookies.length>0)
{
for(Cookie c:cookies)
{
if(c.getName().equals("ListViewCookie"))
{
list = c.getValue();
}
}
}
list+=request.getParameter("id")+",";
//如果浏览记录超过1000条，清零.
String[] arr = list.split(",");
if(arr!=null&&arr.length>0)
{
if(arr.length>=1000)
{
list="";
}
}
Cookie cookie = new Cookie("ListViewCookie",list);
response.addCookie(cookie);
%>
<!-- 浏览过的商品 -->
<td width="30%" bgcolor="#EEE" align="center">
<br>
<b>您浏览过的商品</b><br>
<!-- 循环开始 -->
<%
ArrayList<Items> itemlist = itemDao.getViewList(list);
if(itemlist!=null&&itemlist.size()>0 )
{
System.out.println("itemlist.size="+itemlist.size());
for(Items i:itemlist)
{
%>
<div>
<dl>
<dt>
<a href="details.jsp?id=<%=i.getId()%>"><img src="images/<%=i.getPicture() %>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=i.getName() %></dd>
<dd class="dd_city">产地:<%=i.getCity() %> 价格:<%=i.getPrice() %> ￥ </dd>
</dl>
</div>
<%
}
}
%>
<!-- 循环结束 -->
</td>
</tr>
</table>
</center>
</body>
</html>
Index.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%@ page import="entity.Items"%>
<%@ page import="dao.ItemsDAO"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<style type="text/css">
div{
float:left;
margin: 10px;
}
div dd{
margin:0px;
font-size:10pt;
}
div dd.dd_name
{
color:blue;
}
div dd.dd_city
{
color:#000;
}
</style>
</head>
<body>
<h1>商品展示</h1>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<td>
<!-- 商品循环开始 -->
<%
ItemsDAO itemsDao = new ItemsDAO();
ArrayList<Items> list = itemsDao.getAllItems();
if(list!=null&&list.size()>0)
{
for(int i=0;i<list.size();i++)
{
Items item = list.get(i);
%>
<div>
<dl>
<dt>
<a href="details.jsp?id=<%=item.getId()%>"><img src="images/<%=item.getPicture()%>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=item.getName() %></dd>
<dd class="dd_city">产地:<%=item.getCity() %> 价格:￥ <%=item.getPrice() %></dd>
</dl>
</div>
<!-- 商品循环结束 -->
<%
}
}
%>
</td>
</tr>
</table>
</center>
</body>
</html>
测试:
