淺談MVC(jsp+servlet+JavaBean簡單例項)
阿新 • • 發佈：2018-12-23
MVC（Model View Controller) 旨在分離模型、控制、檢視。是一種分層思想的體現。
專案例項：購物車商品管理
總體設計
1實現DBHelper類
2建立實體類
3建立業務邏輯類(DAO)
4建立控制層
5建立頁面層
1資料庫連線
package util;
import java.sql.*;
public class DBHelper {
public DBHelper() {
// TODO Auto-generated constructor stub
}
private static final String driver="com.mysql.jdbc.Driver" 2實體類
- 商品類
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() == i.getId() && this.getName().equals(i.getName())) {
return true;
} else {
return false;
}
} else {
return false;
}
}
@Override
public String toString() {
return "商品編號" + this.getId() + ",商品名稱" + this.getName();
}
}
- 購物車類
package entity;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
//購物車類
public class Cart {
// 購買商品集合
private HashMap<Items, Integer> goods;
// 購物車總金額
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;
}
//新增商品
public boolean addGoodsInCart(Items item,int number){
if(goods.containsKey(item)){
goods.put(item, goods.get(item)+number);
}else{
goods.put(item, number);
}
calTotalPrice();//重新計算購物車總金額
return true;
}
//刪除
public boolean removeGoodsFromCart(Items item){
goods.remove(item);
return true;
}
//統計總金額
public double calTotalPrice(){
double sum=0.0;
Set<Items> keys= goods.keySet();//獲得鍵集合
Iterator<Items> it=keys.iterator();//獲得迭代器物件
while(it.hasNext()){
Items i= it.next();
sum +=i.getPrice()* goods.get(i);
}
this.setTotalPrice(sum);//設定購物車總金額
return this.getTotalPrice();
}
//測試購物車類
public static void main(String[] args) {
//建立兩個商品物件
Items i1 =new Items(1,"沃特籃球鞋","溫州",200,500,"001.jpg");
Items i2 =new Items(2,"李寧籃球鞋","廣州",300,500,"002.jpg");
Items i3 =new Items(2,"李寧籃球鞋","廣州",300,500,"002.jpg");
Cart c=new Cart();
c.addGoodsInCart(i1, 1);
c.addGoodsInCart(i2, 2);
//再次購買李寧 三雙
c.addGoodsInCart(i3, 3);
//遍歷購物商品集合
Set<Map.Entry<Items, Integer>> items=c.getGoods().entrySet();
for(Map.Entry<Items, Integer> obj:items){
System.out.println(obj);
}
System.out.println("總金額"+c.getTotalPrice());
}
}
DAO層（javabean）
package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import util.DBHelper;
import entity.Items;
//商品的業務邏輯類
public class ItemsDAO {
// 獲得所有的商品資訊
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語句
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.setNumber(rs.getInt("number"));
item.setPrice(rs.getInt("price"));
item.setPicture(rs.getString("picture"));
list.add(item);// 把一個商品加入集合
}
return list; // 返回集合。
} catch (Exception ex) {
ex.printStackTrace();
return null;
} finally {
// 釋放資料集物件
if (rs != null) {
try {
rs.close();
rs = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
// 釋放語句物件
if (stmt != null) {
try {
stmt.close();
stmt = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
// 根據商品編號獲得商品資料
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語句
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.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 {
// 釋放資料集物件
if (rs != null) {
try {
rs.close();
rs = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
// 釋放語句物件
if (stmt != null) {
try {
stmt.close();
stmt = null;
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
//獲取最近瀏覽的前五條商品資訊
public ArrayList<Items> getViewList(String list)
{
System.out.println("list:"+list);
ArrayList<Items> itemlist = new ArrayList<Items>();
int iCount=5; //每次返回前五條記錄
if(list!=null&&list.length()>0)
{
String[] arr = list.split("#");
System.out.println("arr.length="+arr.length);
//如果商品記錄大於等於5條
if(arr.length>=5)
{
for(int i=arr.length-1;i>=arr.length-iCount;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;
}
}
}
Servlet控制層
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import dao.ItemsDAO;
import entity.Cart;
import entity.Items;
public class CartServlet extends HttpServlet {
private String action; // action物件有三個動作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
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
if (request.getParameter("action") != null) {
this.action = request.getParameter("action");
if (action.equals("add"))// 新增商品進購物車
{
if (addToCart(request, response)) {
request.getRequestDispatcher("/success.jsp").forward(request, response);
} else {
request.getRequestDispatcher("/failure.jsp").forward(request, response);
}
}
if(action.equals("show")){ //顯示購物車
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}
if(action.equals("delete")){
if(deleteFromCart(request,response)){
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}else{
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}
}
}
}
private boolean addToCart(HttpServletRequest request, HttpServletResponse response) {
String id = request.getParameter("id");
String number = request.getParameter("num");
Items item = idao.getItemsById(Integer.parseInt(id));
// 是否第一次給購物車新增商品，需要給session中建立一個新的購物車物件
if (request.getSession().getAttribute("cart") == null) {
Cart cart = new Cart();
request.getSession().setAttribute("cart", cart);
}
Cart cart = (Cart) request.getSession().getAttribute("cart");
if (cart.addGoodsInCart(item, Integer.parseInt(number))) {
return true;
} else {
return false;
}
}
private boolean deleteFromCart(HttpServletRequest request,HttpServletResponse response){
String id=request.getParameter("id");
Cart cart=(Cart)request.getSession().getAttribute("cart");
Items item=idao.getItemsById(Integer.parseInt(id));
if(cart.removeGoodsFromCart(item)){
return true;
}else{
return false;
}
}
public CartServlet() {
// TODO Auto-generated constructor stub
}
public void init() throws ServletException {
// Put your code here
}
}
jsp頁面
index.jsp
<%@page import="java.util.ArrayList"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import="entity.Items"%>
<%@ page import="dao.ItemsDAO"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<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="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>
<!-- 商品迴圈開始 -->
<%
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">產地：<%=item.getCity() %> 價格￥：<%=item.getPrice() %></dd>
</dl>
</div>
<!-- 商品迴圈結束 -->
<%
}
}
%>
</td>
</tr>
</table>
</center>
</body>
</html>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">
-->
<link href="css/main.css" rel="stylesheet" type="text/css">
<script type="text/javascript" src="js/lhgcore.js"></script>
<script type="text/javascript" src="js/lhgdialog.js"></script>
<script type="text/javascript">
function selflog_show(id)
{
var num = document.getElementById("number").value;
J.dialog.get({id: 'haoyue_creat',title: '購物成功',width: 600,height:400, link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add', cover:true});
}
function add()
{
var num = parseInt(document.getElementById("number").value);
if(num<100)
{
document.getElementById("number").value = ++num;
}
}
function sub()
{
var num = parseInt(document.getElementById("number").value);
if(num>1)
{
document.getElementById("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>商品詳情</h1>
<a href="index.jsp">首頁</a> >> <a href="index.jsp">商品列表</a>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<!-- 商品詳情 -->
<%
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="5"><img src="images/<%=item.getPicture()%>" width="200" height="160"/></td>
</tr>
<tr>
<td><B><%=item.getName() %></B></td>
</tr>
<tr>
<td>產地：<%=item.getCity()%></td>
</tr>
<tr>
<td>價格：<%=item.getPrice() %>￥</td>
</tr>
<tr>
<td>購買數量：<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(<%=item.getId()%>)"><img src="images/in_cart.png"></a><a href="servlet/CartServlet?action=show"><img src="images/view_cart.jpg"/></a>
</div>
</td>
<%
}
%>
<%
String list ="";
//從客戶端獲得Cookies集合
Cookie[] cookies = request.getCookies();
//遍歷這個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")+"#";
//如果瀏覽記錄超過1000條，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);
%>
<!-- 瀏覽過的商品 -->
<td width="30%" bgcolor="#EEE" align="center">
<br>
<b><font color="#FF7F00">您瀏覽過的商品</font></b><br>
<!-- 迴圈開始 -->
<%
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">產地:<%=i.getCity() %> 價格:<%=i.getPrice() %> ￥ </dd>
</dl>
</div>
<%
}
}
%>
<!-- 迴圈結束 -->
</td>
</tr>
</table>
</center>
</body>
</html>
success.jsp
<%@ page language="java" import="java.util.*" 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 'success.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="style.css">
-->
</head>
<body>
<center>
<img src="images/add_cart_success.jpg"/>
<hr>
<%
String id =