引言：最近在慕课网上学习了基础Jsp入门教学视频，在课程的最后有一个案例项目，以Jsp+JavaBean模式实现商品信息展示的Java Web Project。今天我就简单地回顾一下这个项目的流程。
一. 项目总体介绍
- 预期效果
- 流程概述
° 实现DBHelper类（数据库连接）
° 创建实体类（Items）
° 创建业务逻辑类（ItemsDAO）
° 创建页面层
二. 项目实现
1. DBHelper类设计
在工程目录src文件夹下创建util包，包中新建DBHelper类。
DBHelper类的目的是建立与MySQL数据库的连接。
package util;import java.sql.Connection;import java.sql.DriverManager;public class DBHelper { ???private static final String DRIVER = "com.mysql.jdbc.Driver"; ???private static final String URL = "jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=utf8"; ???private static final String USERNAME = "root"; ???private static final String PASSWORD = "******"; ???private static Connection con = null; ??????//加载数据库驱动 ???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(con==null){ ???con = DriverManager.getConnection(URL, USERNAME, PASSWORD); ???return con; ???} ???return con; ???}}同时不要忘记在工程文件中导入MySQL对应驱动程序的jar包。
在navicat中创建shopping数据库并执行以下语句创建items表和插入数据
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‘);
2. 实体类（Items）设计
Items类中数据成员对应表items的属性，右键Source选择为每个数据成员进行封装。
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; // 商品产地 ???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; ???}}3. 业务逻辑类（ItemsDAO）设计
ItemsDAOS类主要是实现以后要在Jsp页面中运送数据的方法，包括获取所有商品资料，根据id获取对应商品资料和获取浏览记录中最近5条记录。
package dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.ArrayList;import entity.Items;import util.DBHelper;public class ItemsDAOS { ???//获取数据库内所有的商品资料 ???public ArrayList<Items> getAllItems(){ ???????Connection conn = null; ???????PreparedStatement stmt = null; ???????ResultSet rs = null; ???????ArrayList<Items> list = new ArrayList<>(); ?//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.setName(rs.getString("name")); ???????????????item.setCity(rs.getString("city")); ???????????????item.setPrice(rs.getInt("price")); ???????????????item.setNumber(rs.getInt("number")); ???????????????item.setPicture(rs.getString("picture")); ???????????????list.add(item); ?//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 getItemById(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.setName(rs.getString("name")); ???????????????item.setCity(rs.getString("city")); ???????????????item.setPrice(rs.getInt("price")); ???????????????item.setNumber(rs.getInt("number")); ???????????????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5条商品资料 ???public ArrayList<Items> getViewList(String list){ ???????ArrayList<Items> itemList = new ArrayList<>(); ???????int iCount=5;//每次返回前五条记录 ???????if(list!=null&&list.length()>0){ ???????????String[] arr = list.split(","); ???????????????????????if(arr.length>=5) ???????????{ ???????????????for(int i=arr.length-1;i>=arr.length-iCount;i--){ ???????????????????itemList.add(getItemById(Integer.valueOf(arr[i]))); ???????????????} ???????????} ???????????else{ ???????????????for(int i=arr.length-1;i>=0;i--){ ???????????????????itemList.add(getItemById(Integer.valueOf(arr[i]))); ???????????????} ???????????} ???????????return itemList; ???????}else { ???????????return null; ???????} ???}}4. 页面层的设计
最后一步是在jsp页面中实现浏览商品信息。
主页index.jsp
1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> 2 <%@ page import="dao.ItemsDAOS" %> 3 <%@ page import="entity.Items" ?%> 4 <% 5 String path = request.getContextPath(); 6 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 7 %> 8 ?9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">10 <html>11 ??<head>12 ????<base href="<%=basePath%>">13 ????14 ????<title>My JSP ‘index.jsp‘ starting page</title>15 ????<meta http-equiv="pragma" content="no-cache">16 ????<meta http-equiv="cache-control" content="no-cache">17 ????<meta http-equiv="expires" content="0"> ???18 ????<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">19 ????<meta http-equiv="description" content="This is my page">20 ????<!--21 ????<link rel="stylesheet" type="text/css" href="styles.css">22 ????-->23 ????<style type="text/css">24 ????????div{25 ???????????float: left;26 ???????????margin: 10px;27 ????????}28 ????????div dd{29 ???????????margin: 0px;30 ???????????font-size: 10px;31 ????????}32 ????????div dd.dd_name{33 ???????????color: blue;34 ????????}35 ????????div dd.dd_city{36 ???????????color: #000;37 ????????}38 ????</style>39 ??</head>40 ??41 ??<body>42 ????<h1>商品展示</h1>43 ????<hr>44 ????45 ????<center>46 ????<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">47 ??????<tr>48 ????????<td>49 ????????50 ??????????<!-- 商品循环开始 ?-->51 ??????????<%52 ????????????ItemsDAOS itemsDao = new ItemsDAOS();53 ????????????ArrayList<Items> list = itemsDao.getAllItems();54 ????????????if(list!=null&&list.size()>0){55 ????????????????for(int i=0;i<list.size();i++){56 ????????????????????Items item = list.get(i);57 ??????????%> ?58 ???????????<div>59 ???????????<dl>60 ?????????????<dt>61 ???????????????<a href="details.jsp?id=<%=item.getId() %>"><img src="images/<%=item.getPicture() %>" width="120" height="120"></a>62 ?????????????</dt>63 ?????????????<dd class="dd_name"><%=item.getName() %></dd>64 ?????????????<dd class="dd_city">产地：<%=item.getCity() %> 价格：<%=item.getPrice() %></dd>65 ???????????</dl>66 ???????????</div>67 ??????????<!-- 商品循环结束 ?-->68 ??????????<%69 ????????????????}70 ????????????} ?71 ???????????%>72 ???????????73 ????????</td>74 ??????</tr>75 ????</table>76 ????</center>77 ??</body>78 </html>商品详情页details.jsp
?1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> ?2 <%@ page import="dao.ItemsDAOS" %> ?3 <%@ page import="entity.Items" ?%> ?4 <% ?5 String path = request.getContextPath(); ?6 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; ?7 %> ?8 ??9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 10 <html> 11 ??<head> 12 ????<base href="<%=basePath%>"> 13 ?????14 ????<title>My JSP ‘details.jsp‘ starting page</title> 15 ?????16 ????<meta http-equiv="pragma" content="no-cache"> 17 ????<meta http-equiv="cache-control" content="no-cache"> 18 ????<meta http-equiv="expires" content="0"> ????19 ????<meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 20 ????<meta http-equiv="description" content="This is my page"> 21 ?22 ????<style type="text/css"> 23 ????????div{ 24 ???????????float: left; 25 ???????????margin: 10px; 26 ????????} 27 ????????div dd{ 28 ???????????margin: 0px; 29 ???????????font-size: 10px; 30 ????????} 31 ????????div dd.dd_name{ 32 ???????????color: blue; 33 ????????} 34 ????????div dd.dd_city{ 35 ???????????color: #000; 36 ????????} 37 ????</style> 38 ??</head> 39 ???40 ??<body> 41 ????<h1>商品详情</h1> 42 ????<hr> 43 ????<center> 44 ????<table width="750" height="60" cellpadding="0" cellspacing="0" border="0"> 45 ??????<tr> 46 ????????<!-- 商品详情 ?--> 47 ????????<% 48 ????????????ItemsDAOS itemsDao = new ItemsDAOS(); 49 ????????????Items item = itemsDao.getItemById(Integer.valueOf(request.getParameter("id"))); 50 ????????????if(item!=null){ 51 ?????????%> 52 ????????<td width="70%" valign="top"> 53 ??????????<table> 54 ????????????<tr> 55 ??????????????<td rowspan="4"><img src="images/<%=item.getPicture() %>" width="200" height="200"/></td> 56 ????????????</tr> 57 ????????????<tr> 58 ??????????????<td><B><%=item.getName() %></B></td> 59 ????????????</tr> 60 ????????????<tr> 61 ??????????????<td>产地：<%=item.getCity() %></td> 62 ????????????</tr> 63 ????????????<tr> 64 ??????????????<td>价格：<%=item.getPrice() %></td> 65 ????????????</tr> 66 ??????????</table> 67 ????????</td> 68 ????????<% 69 ????????????} 70 ?????????%> 71 ????????<% 72 ????????????String list = ""; 73 ????????????Cookie[] cookies = request.getCookies(); 74 ????????????if(cookies!=null&&cookies.length>0){ 75 ????????????????for(Cookie c: cookies){ 76 ????????????????????if(c.getName().equals("listViewCookie")){ 77 ????????????????????????list = c.getValue(); 78 ????????????????????} 79 ????????????????} ??80 ????????????} 81 ????????????list+=request.getParameter("id")+","; ??82 ????????????//如果浏览记录超过1000条，清零 83 ????????????String[] arr = list.split(","); 84 ????????????if(arr!=null&&arr.length>0){ 85 ????????????????if(arr.length>=1000) 86 ????????????????????list = ""; 87 ????????????} 88 ?????????????89 ????????????Cookie cookie = new Cookie("listViewCookie",list); 90 ????????????response.addCookie(cookie); 91 ?????????%> 92 ?????????<!-- 浏览过的商品 ?--> 93 ?????????<td width="30%" bgcolor="#EEE" align="center"> 94 ???????????<br> 95 ???????????<b>您浏览过的商品</b><br> 96 ???????????<!-- 循环开始 --> 97 ???????????<% 98 ???????????????ArrayList<Items> itemsList = itemsDao.getViewList(list); 99 ???????????????if(itemsList!=null&&itemsList.size()>0){100 ???????????????????for(Items i: itemsList)101 ???????????????????{102 ????????????%>103 ???????????<div>104 ?????????????<dl>105 ???????????????<dt>106 ?????????????????<a href="details.jsp?id="<%=i.getId() %>"><img src="images/<%=i.getPicture() %>" width="120" height="90" border="1"></a>107 ???????????????</dt>108 ???????????????<dd class="dd_name"><%=i.getName() %></dd>109 ???????????????<dd class="dd_city">产地：<%=i.getCity() %> 价格：<%=i.getPrice() %></dd>110 ?????????????</dl>111 ???????????</div>112 ???????????<% 113 ???????????????????} ??????????114 ???????????????} 115 ???????????%>116 ???????????<!-- 循环结束 -->117 ?????????</td>118 ??????</tr>119 ????</table>120 ????</center>121 ??</body>122 </html>三. 项目总结
在Jsp中执行脚本获取Items对象，再通过Items中封装的方法来获取信息在页面上显示。（对象判空不可缺，否则运行服务器加载页面会报错）
Jsp页面 ——参数——> Java类方法
Jsp页面 <——数据—— Java类方法
Jsp基础学习已经告一段落，明天我将整理一下Jsp相关基础知识，之后会通过专业书籍进一步提高对Jsp的了解。
---每天积累一点点，吃水不忘挖井人---
Jsp入门案例（实现简易的商品信息展示）
原文地址：https://www.cnblogs.com/cardiolith/p/9427623.html