JavaWeb 购物车项目(一)

今天的学习主要是完成一个购物车项目，该项目中使用servlet完成，对于不知道servlet不知道如何使用的去看servlet的使用该篇文章，该文章中有教大家如何使用servlet。目录一.项目所需表二.购物车项目实操1.登录操作2.首页操作购物车数据操作：CarServlet,我们在点击首页的加入购物车页面时，会到该类中进行数据操作，将商品添加进购物车3.购物车三.过滤器一.项目所需表我们一共

客行.

8346人浏览 · 2022-04-30 18:52:25

客行. · 2022-04-30 18:52:25 发布

今天的学习主要是完成一个购物车项目，该项目中使用servlet完成，对于不知道servlet不知道如何使用的去看servlet的使用该篇文章，该文章中有教大家如何使用servlet。

购物车数据操作：CarServlet, 我们在点击首页的加入购物车页面时，会到该类中进行数据操作，将商品添加进购物车

3.购物车

三.过滤器

一.项目所需表

我们一共需要使用到四张表格，将代码数据提供给到大家，大家直接拿到数据库中运行，四张表格分别是用户表，商品表，订单表，订单详情表。

create table car_user
(
    id       number primary key,
    account  varchar2(30) not null,
    password varchar(32)  not null
);

comment on column car_user.ID is '用户编号';
comment on column car_user.account is '用户账户';
comment on column car_user.password is '用户密码(MD5)';

create table car_goods
(
    id       number primary key,
    name     varchar2(20)                        not null,
    describe varchar2(100) default '此商品暂时没有介绍🤣' not null,
    price    number                              not null
);

comment on column car_goods.ID is '商品编号';
comment on column car_goods.name is '商品名称';
comment on column car_goods.describe is '商品描述';
comment on column car_goods.price is '用户价格';

create table car_order
(
    id      number primary key,
    user_id number not null,
    total   number not null
);

comment on column car_order.ID is '订单编号';
comment on column car_order.user_id is '谁的订单!';
comment on column car_order.total is '订单总价';

create table car_order_item
(
    id       number primary key,
    order_id number not null,
    goods_id number not null,
    quantity number not null,
    total    number not null
);

comment on column car_order_item.ID is '订单项编号';
comment on column car_order_item.order_id is '哪个订单!';
comment on column car_order_item.goods_id is '哪个商品!';
comment on column car_order_item.quantity is '下单数量';
comment on column car_order_item.total is '订单项总价';

comment on table car_user is '购物车用户表';
comment on table car_goods is '购物车商品表';
comment on table car_order is '购物车订单表';
comment on table car_order_item is '购物车订单项表';

create unique index car_user_account_idx on car_user (account);

insert into car_user
values (1, '2890@fox.com', 'ff9830c42660c1dd1942844f8069b74a');-- root123

insert into car_user
values (2, '2357@fox.com', 'e10adc3949ba59abbe56e057f20f883e');-- 123456

insert into car_goods
select 1, '丝袜奶茶', '冰冰娘娘,很好喝', 99
from dual
union
select 2, '勃勃奶茶', '啊~,好冰冰', 29
from dual
union
select 3, '蜜雪大补丁', '可以加个桃桃🍑', 59
from dual
union
select 4, '臭🐟咖啡', '人气最高', 88
from dual
union
select 5, '雪王咖啡', 'incredible taste', 999
from dual
union
select 6, '拉稀弹筒', '👌,就亿点点', 1
from dual;

insert into car_order_item
values (1, 1, 1, 2, 99 * 2);
insert into car_order_item
values (2, 1, 2, 3, 29 * 3);
insert into car_order_item
values (3, 1, 6, 100, 100);

insert into car_order
values (1, 1, 99 * 2 + 29 * 3 + 100);

insert into car_order_item
values (4, 2, 3, 2, 59 * 2);
insert into car_order_item
values (5, 2, 4, 3, 88 * 3);
insert into car_order_item
values (6, 2, 5, 100, 999 * 100);

insert into car_order
values (2, 2, 59 * 2 + 88 * 3 + 999 * 100);

select *
from car_user;
select *
from car_order;
select *
from car_order_item;
select *
from car_goods;

如图所示：

订单表中显示的数据，肯定是登录进来的用户他的所有订单数据，一个用户对应着多个订单。
订单详情表：对应着订单的编号，商品的编号，我们是根据自己想查看的订单的详细数据，一个订单对应着多件商品。

二.购物车项目实操

该购物车我们具备登录，首页，将商品加入购物车，购物车界面，在实操的时候首先我们需要把需要的包导进去。

文件放置位置

1.登录操作

思路:

登录界面具备的方法就是去到数据库查询用户是否存在，如果用户存在我们就跳转到首页去

pojo包下的用户实体类代码如下： User

package com.yjx.pojo;
/**
 * 用户实体类
 * @author zjjt
 *
 */
public class User {
	 
	private Integer id;
	private String name;
	private String pwd;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPwd() {
		return pwd;
	}
	public void setPwd(String pwd) {
		this.pwd = pwd;
	}
	
	
	public User() {
		// TODO Auto-generated constructor stub
	}
	
	public User(Integer id, String name, String pwd) {
		super();
		this.id = id;
		this.name = name;
		this.pwd = pwd;
	}
	
	
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + "]";
	}
	
	
	

}

用户数据库访问层接口代码如下: IUserDao

package com.yjx.dao;
/**
 * 用户数据访问层接口
 * @author zjjt
 *
 */

import com.yjx.pojo.User;

public interface   IUserDao {
    
	//登录验证
	User login(User u);
}

用户数据库访问层代码如下: 该类中具备登录验证的方法 UserDaoImpl

package com.yjx.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import com.yjx.dao.IUserDao;
import com.yjx.pojo.User;
import com.yjx.util.DBHeper;

public class UserDaoImpl implements IUserDao {
	
	private Connection con;
	private PreparedStatement ps;
	private ResultSet   rs;
      /**
       * 登录验证方法
       */
	@Override
	public User login(User u) {
		try {
			con=DBHeper.getCon();
			ps=con.prepareStatement("select * from car_user where account=?");
			ps.setString(1, u.getName());
			rs=ps.executeQuery();
			if(rs.next()) {
				User user=new User();
				user.setId(rs.getInt(1));
				user.setName(rs.getString(2));
				user.setPwd(rs.getString(3));
				return user;
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}    
}

用户业务逻辑层接口代码如下：IUserBiz

package com.yjx.biz;

import com.yjx.pojo.User;

public interface IUserBiz {
     
	//登录验证方法
	 User login(User u);
}

用户业务逻辑层代码如下：UserBizImpl

package com.yjx.biz.impl;

import org.apache.commons.codec.digest.DigestUtils;

import com.yjx.biz.IUserBiz;
import com.yjx.dao.IUserDao;
import com.yjx.dao.impl.UserDaoImpl;
import com.yjx.pojo.User;

public class UserBizImpl implements IUserBiz {
  
	 IUserDao userdao=new UserDaoImpl();
	
	/**
	 * 登录验证方法
	 */
	  @Override
	public User login(User u) {
		User user=userdao.login(u);
		String pwd=DigestUtils.md5Hex(u.getPwd());
		if(user.getPwd().equals(pwd)) {
			return user;
		}
		return null;
		
	}
}

登录页面代码：login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<!DOCTYPE html>
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<link rel="stylesheet" href="bootstrap-3.3.7-dist/css/bootstrap.css">
<script src="bootstrap-3.3.7-dist/js/jquery-3.5.1.js"></script>
<script src="bootstrap-3.3.7-dist\js\bootstrap.js"></script>
<meta name="viewport" content="width=device-width,initial-scale=1">

<title>登录界面</title>
<style>
form {
	width: 500px;
	margin:auto;
}
</style>
</head>
<body>
	<form action="login.do" method="post">
		<h1>登录</h1>
		<div class="form-group">
			<input name="uname" class="form-control" placeholder="用户名">
		</div>
		<div class="form-group">
			<input name="upwd" class="form-control" placeholder="密码">
		</div>
		<div class="form-group">
			<button class="btn btn-primary btn-block">登录</button>
		</div>
	</form>

</body></html>

实现登录功能代码如下 : LoginServlet

在这里我们将用户存进session中，当用户一进来我们就给用户一个购物车，该购物车中存放我们在首页加入购物车的商品，然后在购物车界面遍历。

package com.yjx.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.biz.IGoodsBiz;
import com.yjx.biz.IUserBiz;
import com.yjx.biz.impl.GoodsBizImpl;
import com.yjx.biz.impl.UserBizImpl;
import com.yjx.pojo.Car;
import com.yjx.pojo.User;
/**
 * 实现登录功能
 * @author zjjt
 *
 */
@WebServlet("/login.do")
public class LoginServlet extends HttpServlet{
	
	IUserBiz userbiz=new UserBizImpl();
	
	IGoodsBiz goodsbiz=new GoodsBizImpl();
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req,resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
		req.setCharacterEncoding("utf-8");
		String name=req.getParameter("uname");
		String pwd=req.getParameter("upwd");
		
		User u=new User(0,name,pwd);
	    userbiz.login(u);
	    if(u!=null) {
	    	//将用户存入session中
	    	req.getSession().setAttribute("user", u);
	    	//进来的时候就给该用户一个购物车,将该购物车存在session中
	    	List<Car> car=new ArrayList<Car>();
	    	req.getSession().setAttribute("car",car);
	    	//总价
	    	req.getSession().setAttribute("sum", 0);
	    	//跳转到实现首页功能
	    	resp.sendRedirect("index.do");
	}else {
		    resp.sendRedirect("login.jsp");
	}

	}
}

2.首页操作

思路:

首页界面需要显示商品表中的数据
点击加入购物车将数据加入进购物车

商品表的pojo包下的商品实体类代码如下:Goods

package com.yjx.pojo;
/**
 * 商品实体类
 * @author zjjt
 *
 */
public class Goods {
 
	private Integer id;
	private String name;
	private String describe;
	private Integer price;
	
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescribe() {
		return describe;
	}
	public void setDescribe(String describe) {
		this.describe = describe;
	}
	public Integer getPrice() {
		return price;
	}
	public void setPrice(Integer price) {
		this.price = price;
	}
	
	public Goods() {
		// TODO Auto-generated constructor stub
	}
	
	
	public Goods(Integer id, String name, String describe, Integer price) {
		super();
		this.id = id;
		this.name = name;
		this.describe = describe;
		this.price = price;
	}
	
	
	
	
	@Override
	public String toString() {
		return "Goods [id=" + id + ", name=" + name + ", describe=" + describe + ", price=" + price + "]";
	}
	
	
	
	
}

商品数据访问层接口： IGoodsDao

package com.yjx.dao;

import java.util.List;

import com.yjx.pojo.Goods;
/**
 * 商品数据访问层的接口
 * @author zjjt
 *
 */
public interface IGoodsDao {
	
	//查询商品表中的所有数据
	List<Goods> selectAll();
	
	//根据id查询
	Goods selestId(int id);
	
	

}

商品数据访问代码如下： GoodsDaoImpl

package com.yjx.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.yjx.dao.IGoodsDao;
import com.yjx.pojo.Goods;
import com.yjx.util.DBHeper;
/**
 * 商品数据访问层
 * @author zjjt
 *
 */
public class GoodsDaoImpl implements IGoodsDao{
	private Connection con;
	private PreparedStatement ps;
	private ResultSet rs;
    
	/**
	 * 查询商品表中的所有数据
	 */
	  @Override
	public List<Goods> selectAll() {
		List<Goods> list=new ArrayList<Goods>();
		try {
			con=DBHeper.getCon();
			ps=con.prepareStatement("select * from car_goods");
			rs=ps.executeQuery();
			while(rs.next()) {
			Goods g=new Goods();
			g.setId(rs.getInt(1));
			g.setName(rs.getString(2));
			g.setDescribe(rs.getString(3));
			g.setPrice(rs.getInt(4));
			list.add(g);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHeper.getColes(con, ps, rs);
		}
		return list;
	}
	 
	  /**
	   * 根据商品id进行查询
	   */
	  @Override
	public Goods selestId(int id) {
		  try {
				con=DBHeper.getCon();
				ps=con.prepareStatement("select * from car_goods where id=?");
				ps.setInt(1, id);
				rs=ps.executeQuery();
				if(rs.next()) {
				Goods g=new Goods();
				g.setId(rs.getInt(1));
				g.setName(rs.getString(2));
				g.setDescribe(rs.getString(3));
				g.setPrice(rs.getInt(4));
				return g;
				}
			} catch (Exception e) {
				e.printStackTrace();
			}finally {
				DBHeper.getColes(con, ps, rs);
			}
		   return null;
	}
}

商品数据业务逻辑层接口代码如下:IGoodsBiz

package com.yjx.biz;

import java.util.List;

import com.yjx.pojo.Goods;
/**
 * 商品业务逻辑层接口
 * @author zjjt
 *
 */
public interface IGoodsBiz {

	//查询商品表中的所有数据
	List<Goods> selectAll();
	
	//根据id查询
     Goods selestId(int id);

}

商品数据业务逻辑层代码如下: GoodsBizImpl

package com.yjx.biz.impl;

import java.util.List;

import com.yjx.biz.IGoodsBiz;
import com.yjx.dao.IGoodsDao;
import com.yjx.dao.impl.GoodsDaoImpl;
import com.yjx.pojo.Goods;
/**
 * 商品业务逻辑层
 * @author zjjt
 *
 */
public class GoodsBizImpl implements IGoodsBiz{
	
	IGoodsDao dao=new GoodsDaoImpl();
  
	/**
	 * 查询商品表中所有数据
	 */
	   @Override
	public List<Goods> selectAll() {
		
		return dao.selectAll();
	}
	   
	   /**
	    * 根据id查询
	    */
	   @Override
	public Goods selestId(int id) {
		
		return dao.selestId(id);
	}
}

商品数据操作代码如下: 所以登录成功后先跳转到这里，在将商品数据从全查出来，然后存进session中，在首页的时候在遍历 IndexServlet

package com.yjx.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.biz.IGoodsBiz;
import com.yjx.biz.impl.GoodsBizImpl;
import com.yjx.pojo.Goods;
/**
 * 首页商品数据显示
 * @author zjjt
 *
 */
@WebServlet("/index.do")
public class IndexServlet extends HttpServlet{
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
		IGoodsBiz goodsbiz=new  GoodsBizImpl();
	    List<Goods> list=goodsbiz.selectAll();
	    
	    //将该集合中的数据存进request中
	    req.setAttribute("goods", list);
	    //使用request存放，需要转发
	    req.getRequestDispatcher("index.jsp").forward(req, resp);
	    		
	}

}

首页界面代码如下：index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!-- 商品首页 -->

<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<link rel="stylesheet" href="bootstrap-3.3.7-dist/css/bootstrap.css">
<script src="bootstrap-3.3.7-dist/js/jquery-3.5.1.js"></script>
<script src="bootstrap-3.3.7-dist\js\bootstrap.js"></script>
<meta name="viewport" content="width=device-width,initial-scale=1">
<style>
body {
	padding: 20px 40px;
}
</style>
</head>
<body>
	<h1>
		${user.name}<small>这是首页</small>
	</h1>
	<h1>
		<a class="btn btn-primary" href="car.jsp">点我去购物车🛒</a>
	</h1>
	<table class="table table-bordered table-striped">
		<tbody><tr>
			<th>商品编号</th>
			<th>商品名称</th>
			<th>商品价格</th>
			<th>商品操作</th>
		</tr>
		<!-- 遍历 -->
   <c:forEach items="${goods}" var="g">
 		<tr>
			<td>${g.id}</td>
			<td>${g.name}</td>
			<td>${g.price}</td>
			<td><a href="car.do?id=${g.id}" class="btn btn-default">加入🚗</a></td>
		</tr>
		
  </c:forEach>

</body></html>

购物车数据操作：CarServlet, 我们在点击首页的加入购物车页面时，会到该类中进行数据操作，将商品添加进购物车

package com.yjx.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.biz.IGoodsBiz;
import com.yjx.biz.impl.GoodsBizImpl;
import com.yjx.pojo.Car;
import com.yjx.pojo.Goods;

/**
 * 购物车数据
 * @author zjjt
 *
 */
@WebServlet("/car.do")
public class CarServlet extends HttpServlet{
	
	IGoodsBiz goodsbiz=new GoodsBizImpl();
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
	
	List<Car> car=(List<Car>)req.getSession().getAttribute("car");
	//先将传过来的id接收到
	int id=Integer.parseInt(req.getParameter("id"));
	boolean f=true;
	
	//判断该商品是否已经存在购物车中，如何存在只在数量上相加
	 for (Car c : car) {
		if(c.getGoods().getId()==id) {
			//设置数量加1
		   c.setCount(c.getCount()+1);
		   //设置商品总价
		   c.setTotal(c.getCount()*c.getGoods().getPrice());
		   f=false;
		   break;
		}
	}
	
	 if(f) {
	//当商品不存在相同的进入这里
	//根据id进行查询商品
	Goods goods=goodsbiz.selestId(id);
	Car c=new Car();
	c.setGoods(goods);
	//商品的数量设置
	c.setCount(1);
	//商品的总价设置
	c.setTotal(c.getGoods().getPrice());
    car.add(c);
	}
	
	 //遍历购物车将总价加上
	 int sum=0;
	 for (Car car2 : car) {
		sum+=car2.getTotal();
	}
	 req.getSession().setAttribute("sum",sum);
	 
	 resp.sendRedirect("index.do");
	}
     
	
}

3.购物车

购物车中具备查看我们加入购物和的商品，然后对商品的数量增加减，当商品存在购物车中了，我们在首页将同一件商品在加入购物车时，只有数量加1。

购物车的pojo包下的实体类代码如下:Car

package com.yjx.pojo;
/**
 * 购物车实体类
 * @author zjjt
 *
 */
public class Car {
	
	private Goods  goods;
	private Integer count;
	private Integer total;
	
	
	public Goods getGoods() {
		return goods;
	}
	public void setGoods(Goods goods) {
		this.goods = goods;
	}
	public Integer getCount() {
		return count;
	}
	public void setCount(Integer count) {
		this.count = count;
	}
	public Integer getTotal() {
		return total;
	}
	public void setTotal(Integer total) {
		this.total = total;
	}
	
	
	public Car() {
		// TODO Auto-generated constructor stub
	}
	
	public Car(Goods goods, Integer count, Integer total) {
		super();
		this.goods = goods;
		this.count = count;
		this.total = total;
	}
	
	
	
	
	

}

购物车页面代码如下: car.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="c"  uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html>
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<link rel="stylesheet" href="bootstrap-3.3.7-dist/css/bootstrap.css">
<script src="bootstrap-3.3.7-dist/js/jquery-3.5.1.js"></script>
<script src="bootstrap-3.3.7-dist\js\bootstrap.js"></script>
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>我的购物车</title>
</head>
<body>
<div class="container">
	<h1>
		${user.name}<small>这是购物车</small>
	</h1>
	<h1>
		<button onclick="location.href=&#39;index.do&#39;" class="btn btn-default">继续购买</button>
		<button onclick="location.href=&#39;calc.do&#39;" class="btn btn-default">订单结算</button>
		<button onclick="location.href=&#39;myOrder.do&#39;" class="btn btn-default">查看订单</button>
	</h1>
	<table class="table table-bordered table-striped">
		<tr>
			<td>商品编号</td>
			<td>商品名字</td>
			<td>商品单价</td>
			<td>商品数量</td>
			<td>商品总价</td>
			<td>商品操作</td>
		</tr>
		<c:forEach items="${car}" var="c">
		<tr>
			<td>${c.goods.id}</td>
			<td>${c.goods.name}</td>
			<td>${c.goods.price}</td>
			<td><a href="updCar.do?id=${c.goods.id}&type=1" class="btn btn-default">+</a>   ${c.count}   <a href="updCar.do?id=${c.goods.id}&type=-1" class="btn btn-default">-</a></td>
			<td>${c.total}</td>
			<td><a href="delCar.do?id=${c.goods.id}" class="btn btn-default">商品删除</a></td>
			
		</tr>
		</c:forEach>
      </table>
	</div>
	
	<h1>总价:${sum}</h1>

</body></html>

点击加号或者减号数据操作代码如下：updCarServlet

当点击加号或者减号携带过来一个数，判断是加法还是减法，进行对数量上的加减

package com.yjx.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.biz.IGoodsBiz;
import com.yjx.biz.impl.GoodsBizImpl;
import com.yjx.pojo.Car;
import com.yjx.pojo.Goods;

/**
 * 修改商品数量操作
 * @author zjjt
 *
 *
 */

@WebServlet("/updCar.do")
public class updCarServlet extends HttpServlet{
	
	
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
	 doPost(req, resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//拿到购物车
		List<Car> car=(List<Car>)req.getSession().getAttribute("car");
		//接收到传过来的值
		int id=Integer.parseInt(req.getParameter("id"));
		int type=Integer.parseInt(req.getParameter("type"));
		
		for (Car c : car) {
			 if(c.getGoods().getId().equals(id)) {
				 int count=c.getCount()+type;
				//设置该商品的数量
				 if(count<1)break;
				 
	            c.setCount(count);
	            c.setTotal(c.getCount()*c.getGoods().getPrice());
			 }
		}
		
		 //遍历购物车将总价加上
		 int sum=0;
		 for (Car car2 : car) {
			sum+=car2.getTotal();
		}
		 req.getSession().setAttribute("sum",sum);
		
		 resp.sendRedirect("car.jsp");
	}
	

}

购物车数据删除代码如下： delCarServlet

package com.yjx.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.pojo.Car;

/**
 * 删除商品操作
 * @author zjjt
 *
 */
@WebServlet("/delCar.do")
public class delCarServlet extends HttpServlet{
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//拿到购物车
		List<Car> car=(List<Car>)req.getSession().getAttribute("car");
		//先接收到id
	   int id=Integer.parseInt(req.getParameter("id"));
	    Car i=null;
	   //遍历购物车
	   for (Car c : car) {
		 if(c.getGoods().getId().equals(id)){
			 i=c;
		 }
	}
	   //将商品删除
	   car.remove(i);
	   
	   //遍历购物车将总价加上
		 int sum=0;
		 for (Car car2 : car) {
			sum+=car2.getTotal();
		}
		 req.getSession().setAttribute("sum",sum);
	   
	   resp.sendRedirect("car.jsp");
	}
	
	

}

三.过滤器

过滤器的作用，就是当我们没有登录时，有一些界面无法进入，所以我们进在过滤器中进行过滤，满足我们条件的我们就放行，不满足条件的就让他继续在登录页面。

package com.yjx.filter;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yjx.pojo.User;

/**
 * 过滤
 * @author zjjt
 *
 */
public class LoginFilter implements Filter{
	//过滤的作用：因为当我们没有登录成功时，只有允许在登录界面，不允许跳转到别的界面，所以我们选择使用过滤，不满足我们进入的
	//        需求就让他跳回登录界面。
	
	
      //1.先实现filter接口
	  //2.先实例一个集合，将我们需要放行的页面放入
	  List<String> list=new ArrayList();
	  
	  {
		  list.add("/login.jsp");
		  list.add("/login.do");
		  list.add(".css");
		  list.add(".js");
	  }
	  
	  
	@Override
public void doFilter(ServletRequest req, ServletResponse reps, FilterChain chain)throws IOException, ServletException {
	  //将请求和响应强转成它的子类
	  HttpServletRequest request=(HttpServletRequest)req;
	  HttpServletResponse response=(HttpServletResponse)reps;
	  
	  //获取到路径
	 String path=request.getServletPath();
	 boolean f=false;
	 //遍历集合和获取到的路径进行判断
	 for(String p:list) {
		 if(path.endsWith(p)){//判断是否是以增加进集合的的数据结尾的
			 //如果以该为结尾的话
			 f=true;
			 System.out.print(f);
			 break;
		 }
	 }
	  
	
	 if(f){
		 //如果存在list集合中就放行
		 chain.doFilter(request, response);//放行语句
		  return;
	 }
	 
	 //判断用户是否已经登录啦，如果session中存在user那么就放行
	      User u=(User)request.getAttribute("user");//得到一个用户进行判断
	      if(u!=null) {
	    	  chain.doFilter(request, response);
	      }else {
	    	  //用户没有登录就返回登录界面
	    	  response.sendRedirect("login.jsp");
	      }
		
	}
	
}

今天的学习就到这里啦。