MVC（Model View Controller) 旨在分离模型、控制、视图。是一种分层思想的体现。
项目实例：购物车商品管理
总体设计
1实现DBHelper类
2创建实体类
3创建业务逻辑类(DAO)
4创建控制层
5创建页面层
1数据库连接
package util;
import .*;
public class DBHelper {
public DBHelper() {
// TODO Auto-generated constructor stub
}
private static final String driver="";
private static final String url="jdbc:mysql://localhost:3306/shopping";
private static final String username="root";
private static final String password="123";
private static Connection con;
//加载驱动
static
{
try{
(driver);
}catch (Exception e) {
( );
}
}
//单例模式返回数据库对象
public static Connection getConnection() throws Exception {
if(con==null){
con=(url,username,password);
return con;
}
return con;
}
public static void main(String[] args) {
try {
Connection con=();
if(con!=null){
("连接正常！");
}else{
("连接异常！");
}
} catch (Exception e) {
// TODO Auto-generated catch block
();
}
}
}
2实体类
- 商品类
package entity;
public class Items {
private int id;
private String name;
private String city;
private int price;
private int number;
private String picture;
public Items() {
}
public Items(int id, String name, String city, int price, int number, String picture) {
this.id = id;
this.name = name;
this.city = city;
this.price = price;
this.number = number;
this.picture = picture;
}
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;
}
@Override
public int hashCode() {
// TODO Auto-generated method stub
return this.getId() + this.getName().hashCode();
}
@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
if (this == obj) {
return true;
}
if (obj instanceof Items) {
Items i = (Items) obj;
if (this.getId() == () && this.getName().equals(())) {
return true;
} else {
return false;
}
} else {
return false;
}
}
@Override
public String toString() {
return "商品编号" + this.getId() + ",商品名称" + this.getName();
}
}
- 购物车类
package entity;
import ;
import ;
import ;
import ;
//购物车类
public class Cart {
// 购买商品集合
private HashMap<Items, Integer> goods;
// 购物车总金额
private double totalPrice;
public Cart() {
goods = new HashMap<Items, Integer>();
totalPrice = 0.0;
}
public HashMap<Items, Integer> getGoods() {
return goods;
}
public void setGoods(HashMap<Items, Integer> goods) {
this.goods = goods;
}
public double getTotalPrice() {
return totalPrice;
}
public void setTotalPrice(double totalPrice) {
this.totalPrice = totalPrice;
}
//添加商品
public boolean addGoodsInCart(Items item,int number){
if((item)){
(item, (item)+number);
}else{
(item, number);
}
calTotalPrice();//重新计算购物车总金额
return true;
}
//删除
public boolean removeGoodsFromCart(Items item){
(item);
return true;
}
//统计总金额
public double calTotalPrice(){
double sum=0.0;
Set<Items> keys= ();//获得键集合
Iterator<Items> it=();//获得迭代器对象
while(()){
Items i= ();
sum +=()* (i);
}
this.setTotalPrice(sum);//设置购物车总金额
return this.getTotalPrice();
}
//测试购物车类
public static void main(String[] args) {
//创建两个商品对象
Items i1 =new Items(1,"沃特篮球鞋","温州",200,500,"");
Items i2 =new Items(2,"李宁篮球鞋","广州",300,500,"");
Items i3 =new Items(2,"李宁篮球鞋","广州",300,500,"");
Cart c=new Cart();
(i1, 1);
(i2, 2);
//再次购买李宁 三双
(i3, 3);
//遍历购物商品集合
Set<<Items, Integer>> items=().entrySet();
for(<Items, Integer> obj:items){
(obj);
}
("总金额"+());
}
}
DAO层（javabean）
package dao;
import ;
import ;
import ;
import ;
import ;
import ;
//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 = ();
String sql = "select * from items;"; // SQL语句
stmt = (sql);
rs = ();
while (()) {
Items item = new Items();
(("id"));
(("name"));
(("city"));
(("number"));
(("price"));
(("picture"));
(item);// 把一个商品加入集合
}
return list; // 返回集合。
} catch (Exception ex) {
();
return null;
} finally {
// 释放数据集对象
if (rs != null) {
try {
();
rs = null;
} catch (Exception ex) {
();
}
}
// 释放语句对象
if (stmt != null) {
try {
();
stmt = null;
} catch (Exception ex) {
();
}
}
}
}
// 根据商品编号获得商品资料
public Items getItemsById(int id) {
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = ();
String sql = "select * from items where id=?;"; // SQL语句
stmt = (sql);
(1, id);
rs = ();
if (()) {
Items item = new Items();
(("id"));
(("name"));
(("city"));
(("number"));
(("price"));
(("picture"));
return item;
} else {
return null;
}
} catch (Exception ex) {
();
return null;
} finally {
// 释放数据集对象
if (rs != null) {
try {
();
rs = null;
} catch (Exception ex) {
();
}
}
// 释放语句对象
if (stmt != null) {
try {
();
stmt = null;
} catch (Exception ex) {
();
}
}
}
}
//获取最近浏览的前五条商品信息
public ArrayList<Items> getViewList(String list)
{
("list:"+list);
ArrayList<Items> itemlist = new ArrayList<Items>();
int iCount=5; //每次返回前五条记录
if(list!=null&&()>0)
{
String[] arr = ("#");
("="+);
//如果商品记录大于等于5条
if(>=5)
{
for(int i=-1;i>=-iCount;i--)
{
(getItemsById((arr[i])));
}
}
else
{
for(int i=-1;i>=0;i--)
{
(getItemsById((arr[i])));
}
}
return itemlist;
}
else
{
return null;
}
}
}
Servlet控制层
package servlet;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
public class CartServlet extends HttpServlet {
private String action; // action对象有三个动作add show delete
private ItemsDAO idao = new ItemsDAO();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
("text/html;charset=utf-8");
PrintWriter out = ();
if (("action") != null) {
this.action = ("action");
if (("add"))// 添加商品进购物车
{
if (addToCart(request, response)) {
("/").forward(request, response);
} else {
("/").forward(request, response);
}
}
if(("show")){ //显示购物车
("/").forward(request, response);
}
if(("delete")){
if(deleteFromCart(request,response)){
("/").forward(request, response);
}else{
("/").forward(request, response);
}
}
}
}
private boolean addToCart(HttpServletRequest request, HttpServletResponse response) {
String id = ("id");
String number = ("num");
Items item = ((id));
// 是否第一次给购物车添加商品，需要给session中创建一个新的购物车对象
if (().getAttribute("cart") == null) {
Cart cart = new Cart();
().setAttribute("cart", cart);
}
Cart cart = (Cart) ().getAttribute("cart");
if ((item, (number))) {
return true;
} else {
return false;
}
}
private boolean deleteFromCart(HttpServletRequest request,HttpServletResponse response){
String id=("id");
Cart cart=(Cart)().getAttribute("cart");
Items item=((id));
if((item)){
return true;
}else{
return false;
}
}
public CartServlet() {
// TODO Auto-generated constructor stub
}
public void init() throws ServletException {
// Put your code here
}
}
jsp页面
<%@page import=""%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import=""%>
<%@ page import=""%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http:///TR/html4/">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<!--
<link rel="stylesheet" type="text/css" href="">
-->
<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=();
if(list!=null&&()>0)
{
for(int i=0;i<();i++)
{
Items item = list.get(i);
%>
<div>
<dl>
<dt>
<a href="?id=<%=()%>"><img src="images/<%=()%>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=() %></dd>
<dd class="dd_city">产地：<%=() %> 价格￥：<%=() %></dd>
</dl>
</div>
<!-- 商品循环结束 -->
<%
}
}
%>
</td>
</tr>
</table>
</center>
</body>
</html><%@ page language="java" import=".*" contentType="text/html; charset=utf-8" %>
<%@ page import=""%>
<%@ page import=""%>
<%
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 '' 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="">
-->
<link href="css/" rel="stylesheet" type="text/css">
<script type="text/javascript" src="js/"></script>
<script type="text/javascript" src="js/"></script>
<script type="text/javascript">
function selflog_show(id)
{
var num = ("number").value;
({id: 'haoyue_creat',title: '购物成功',width: 600,height:400, link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add', cover:true});
}
function add()
{
var num = parseInt(("number").value);
if(num<100)
{
("number").value = ++num;
}
}
function sub()
{
var num = parseInt(("number").value);
if(num>1)
{
("number").value = --num;
}
}
</script>
<style type="text/css">
hr{
border-color:FF7F00;
}
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;
}
div #cart
{
margin:0px auto;
text-align:right;
}
span{
padding:0 2px;border:1px #c0c0c0 solid;cursor:pointer;
}
a{
text-decoration: none;
}
</style>
</head>
<body>
<h1>商品详情</h1>
<a href="">首页</a> >> <a href="">商品列表</a>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<!-- 商品详情 -->
<%
ItemsDAO itemDao = new ItemsDAO();
Items item = ((request.getParameter("id")));
if(item!=null)
{
%>
<td width="70%" valign="top">
<table>
<tr>
<td rowspan="5"><img src="images/<%=()%>" width="200" height="160"/></td>
</tr>
<tr>
<td><B><%=() %></B></td>
</tr>
<tr>
<td>产地：<%=()%></td>
</tr>
<tr>
<td>价格：<%=() %>￥</td>
</tr>
<tr>
<td>购买数量：<span id="sub" onclick="sub();">-</span><input type="text" id="number" name="number" value="1" size="2"/><span id="add" onclick="add();">+</span></td>
</tr>
</table>
<div id="cart">
<img src="images/buy_now.png"><a href="javascript:selflog_show(<%=()%>)"><img src="images/in_cart.png"></a><a href="servlet/CartServlet?action=show"><img src="images/view_cart.jpg"/></a>
</div>
</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&&>0)
{
for(Cookie c:cookies)
{
if(().equals("ListViewCookie"))
{
list = ();
}
}
}
list+=request.getParameter("id")+"#";
//如果浏览记录超过1000条，清零.
String[] arr = list.split("#");
if(arr!=null&&>0)
{
if(>=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><font color="#FF7F00">您浏览过的商品</font></b><br>
<!-- 循环开始 -->
<%
ArrayList<Items> itemlist = (list);
if(itemlist!=null&&()>0 )
{
("="+());
for(Items i:itemlist)
{
%>
<div>
<dl>
<dt>
<a href="?id=<%=()%>"><img src="images/<%=() %>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=() %></dd>
<dd class="dd_city">产地:<%=() %> 价格:<%=() %> ￥ </dd>
</dl>
</div>
<%
}
}
%>
<!-- 循环结束 -->
</td>
</tr>
</table>
</center>
</body>
</html>
<%@ page language="java" import=".*" contentType="text/html; charset=utf-8"%>
<%
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 '' 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="">
-->
</head>
<body>
<center>
<img src="images/add_cart_success.jpg"/>
<hr>
<%
String id = request.getParameter("id");
String num = request.getParameter("num");
%>
您成功购买了<%=num%>件商品编号为<%=id%>的商品
<br>
<br>
<br>
</center>
</body>
</html>
<%@ page language="java" import=".*" contentType="text/html; charset=utf-8"%>
<%
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 '' 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="">
-->
</head>
<body>
<center>
<img src="images/add_cart_failure.jpg"/>
<hr>
<br>
<br>
<br>
</center>
</body>
</html>
<%@ page language="java" import=".*" contentType="text/html; charset=utf-8"%>
<%@ page import="" %>
<%@ page import="" %>
<%
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 '' 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="">
-->
<link type="text/css" rel="stylesheet" href="css/" />
<script language="javascript">
function delcfm(){
if(!comfirm("确认要删除？")){
=false;
}
}
</script>
</head>
<body>
<h1>我的购物车</h1>
<a href="">首页</a> >> <a href="">商品列表</a>
<hr>
<div id="shopping">
<form action="" method="">
<table>
<tr>
<th>商品名称</th>
<th>商品单价</th>
<th>商品价格</th>
<th>购买数量</th>
<th>操作</th>
</tr>
<%
//首先判断session中是否有购物车对象
if(request.getSession().getAttribute("cart")!=null)
{
%>
<!-- 循环的开始 -->
<%
Cart cart=(Cart)request.getSession().getAttribute("cart");
HashMap<Items,Integer> goods=();
Set<Items> items=();
Iterator<Items> it=();
while(()){
Items i=it.next();
%>
<tr name="products" id="product_id_1">
<td class="thumb"><img src="images/<%=()%>" /><a href=""><%=()%></a></td>
<td class="number"><%=() %></td>
<td class="price" id="price_id_1">
<span><%=()*goods.get(i) %></span>
<input type="hidden" value="" />
</td>
<td class="number">
<%=goods.get(i)%>
</td>
<td class="delete">
<a href="servlet/CartServlet?action=delete&id=<%=()%>" onclick="delcfm();">删除</a> <!-- onclick 调用js删除方法 -->
</td>
</tr>
<%
}
%>
<!--循环的结束-->
</table>
<div class="total"><span id="total">总计：<%=() %>￥</span></div>
<%
}
%>
<div class="button"><input type="submit" value="" /></div>
</form>
</div>
</body>
</html>
servlet类一定不要忘记配置xml文档！！！切记！！
<servlet>
<servlet-name>CartServlet</servlet-name>
<servlet-class></servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CartServlet</servlet-name>
<url-pattern>/servlet/CartServlet</url-pattern>
</servlet-mapping>
参照慕课网课程项目实例