使用c3p0：购物车示例

 1 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 2 <%--
 3   Created by IntelliJ IDEA.
 4   User: tony
 5   Date: 2019/8/29
 6   Time: 16:53
 7   To change this template use File | Settings | File Templates.
 8 --%>
 9 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
10 
11 
12     
13     <%--导入bootstrap框架--%>
14     
15     
16     
17 
18 
19 
20 
class="container">
21 
22     
class="panel panel-primary">
23         
class="panel-heading">
24             
我的购物车
25         
26         
class="panel-body">
27 
28             class="table table-striped table-bordered table-hover text-center">
2930313233343536373839404142
43                     4445464748495055565960616263666768
 
                 

                     
编号
                     
图片
                     
菜名
                     
风味
                     
餐馆
                     
价格
                     
数量
                     
小计
                     
操作
                 
 
                 

                         
${m.value.fid}
                         

                         
${m.value.fname}
                         
${m.value.ftype}
                         
${m.value.fshop}
                         
${m.value.fprice}.00元
                         

51                             class="btn btn-primary glyphicon glyphicon-minus">
52                                 ${m.value.itemNum}
53                             class="btn btn-primary glyphicon glyphicon-plus">
54                         
                         
${m.value.itemPrice}.00元
                         

57                             class="btn btn-danger" href="/food?param=removeall&fid=${m.value.fid}">移除全部
58                         
                     
                 
 
                 

                     

64                         数量共：${car.sumnum}件， 总金额：${car.sumprice}.00元，
65                     
                 
 
             
69             class="btn btn-success btn-lg btn-block" href="/food?param=list">继续点餐
70         
71 
72         
class="panel-footer text-right">
73             海底捞列表页
74         
75     
76 
77 
78 
79 
80 

 1 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 2 <%--
 3   Created by IntelliJ IDEA.
 4   User: Administrator
 5   Date: 2019/8/29
 6   Time: 19:57
 7   To change this template use File | Settings | File Templates.
 8 --%>
 9 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
10 
11 
12     
13     
14     
15     
16 
17 
18     
class="container">
19         
class="panel panel-primary">
20             
class="panel-heading">
21                 
海底捞列表页
22             
23             
class="panel-body">
24                 
class="form-group">
25                     
class="row">
26                         
27                             
class="col-md-3">
28                                 
class="thumbnail">
29                                     
30                                     
class="caption">
31                                         
${f.fname}(${f.fshop}:${f.ftype})
32                                         
￥：${f.fprice}元
33                                         

34                                             class="btn btn-primary" role="button">开始点餐
35                                             class="btn btn-warning" role="button">查看评论
36                                         
37                                     
38                                 
39                             
40                         
41                     
42                 
43                 class="btn btn-primary col-md-3 btn-lg" style="float: right;">查看购物车
44             
45             
class="panel-footer text-right">
46                 海底捞列为您服务
47             
48         
49     
50 
51 

  1 package com.food.servlet;
  2 
  3 import com.food.dao.FoodDao;
  4 import com.food.entity.Car;
  5 import com.food.entity.Car2;
  6 import com.food.entity.CarItem;
  7 import com.food.entity.Food;
  8 
  9 import javax.servlet.ServletException;
 10 import javax.servlet.annotation.WebServlet;
 11 import javax.servlet.http.HttpServlet;
 12 import javax.servlet.http.HttpServletRequest;
 13 import javax.servlet.http.HttpServletResponse;
 14 import javax.servlet.http.HttpSession;
 15 import java.io.IOException;
 16 import java.math.BigDecimal;
 17 import java.util.HashMap;
 18 import java.util.Map;
 19 
 20 @WebServlet("/food")
 21 public class FoodServlet extends HttpServlet {
 22     //需要一个dao对象
 23     private FoodDao foodDao = new FoodDao();
 24 
 25     /**
 26      * dopost，根据参数名判断进入哪一个servlet
 27      * @param request
 28      * @param response
 29      * @throws ServletException
 30      * @throws IOException
 31      */
 32     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 33         doGet(request,response);
 34     }
 35 
 36     /**
 37      * doget
 38      * @param request
 39      * @param response
 40      * @throws ServletException
 41      * @throws IOException
 42      */
 43     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 44         String param = request.getParameter("param");//param=list
 45         if (!(param==null || "".equals(param))){
 46             if ("list".equals(param)){////展示所有的菜品信息
 47                 foodlist(request,response);
 48             } else if ("add".equals(param)) {//点餐
 49                 foodadd(request,response);
 50             } else if ("view".equals(param)) {//查看购物车
 51                 foodview(request,response);
 52             } else if ("removeall".equals(param)){
 53                 foodremoveall(request,response);
 54             } else if("change".equals(param)){
 55                 foodchange(request,response);
 56             }else{
 57                 throw new RuntimeException("参数错误。。。。");
 58             }
 59         }
 60 
 61     }
 62 
 63     /**
 64      * 购物车中加-减按钮servlet
 65      * @param request
 66      * @param response
 67      * @throws IOException
 68      */
 69     private void foodchange(HttpServletRequest request, HttpServletResponse response) throws IOException {
 70         HttpSession session = request.getSession();
 71         Car2 car = (Car2) session.getAttribute("car");
 72         Map map = car.getMap();
 73         String cha = request.getParameter("cha");
 74         String fid = request.getParameter("fid");
 75         CarItem carItem = map.get(Integer.parseInt(fid));
 76         if ("jian".equals(cha)){
 77             if (carItem.getItemNum()-1<1){
 78                 carItem.setItemNum(0);
 79             }else{
 80                 carItem.setItemNum(carItem.getItemNum()-1);
 81             }
 82         }else if ("jia".equals(cha)){
 83             carItem.setItemNum(carItem.getItemNum()+1);
 84         }
 85         map.put(Integer.parseInt(fid),carItem);
 86         car.setMap(map);
 87         session.setAttribute("car",car);
 88         response.sendRedirect("/html/foodcar.jsp");
 89     }
 90 
 91     /**
 92      * 购物车中移除按钮servlet
 93      * @param request
 94      * @param response
 95      * @throws IOException
 96      */
 97     private void foodremoveall(HttpServletRequest request, HttpServletResponse response) throws IOException {
 98         String fid = request.getParameter("fid");
 99         HttpSession session = request.getSession();
100         Car2 car = (Car2)session.getAttribute("car");
101         Map map = car.getMap();
102         map.remove(Integer.parseInt(fid));
103         car.setMap(map);
104         session.setAttribute("car",car);
105         response.sendRedirect("/html/foodcar.jsp");
106     }
107 
108     /**
109      * 菜品展示servlet
110      * @param request
111      * @param response
112      * @throws IOException
113      */
114     private void foodview(HttpServletRequest request, HttpServletResponse response) throws IOException {
115         response.sendRedirect("/html/foodcar.jsp");
116     }
117 
118     /**
119      * 菜品添加servlet
120      * @param request
121      * @param response
122      * @throws ServletException
123      * @throws IOException
124      */
125     private void foodadd(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
126         //获取菜品id
127         String foodid = request.getParameter("foodid");
128         //找到菜品
129         Food food = foodDao.findFoodById(Integer.parseInt(foodid));
130         //构造一个session
131         HttpSession session = request.getSession();
132         //从session中拿购物车(car)对象
133         Object obj = session.getAttribute("car");
134         //声明一个map对象
135         Map map = null;
136         //构造一个空的购物车
137         Car2 car = new Car2();
138         if (obj == null){//第一次添加到购物车
139             //构造一个map对象
140             map = new HashMap<>();
141             //构造子项
142             CarItem i = new CarItem();
143             i.setImg(food.getImg());
144             i.setFname(food.getFname());
145             i.setFshop(food.getFshop());
146             i.setFtype(food.getFtype());
147             i.setFid(food.getFid());
148             i.setFprice(food.getFprice());
149             //小计金额与小计数量
150             i.setItemNum(1);
151             i.setItemPrice(food.getFprice()*1);
152             //添加到集合中
153             map.put(food.getFid(),i);
154         }else {//购物车中有小项
155             //判断添加的菜品是否有重复的,怎么判断?
156             map = ((Car2)obj).getMap();//转换为购物车对象,从购物车中拿到map对象
157             boolean b = map.keySet().contains(food.getFid());//根据菜品的id判断
158             if (b){//重复的菜品,数量加一，小计已经在CarItem类中计算了
159                 CarItem carItem = map.get(food.getFid());
160                 carItem.setItemNum(carItem.getItemNum()+1);
161             }else{//不是重复的菜品
162                 //构造子项
163                 CarItem i = new CarItem();
164                 i.setImg(food.getImg());
165                 i.setFname(food.getFname());
166                 i.setFshop(food.getFshop());
167                 i.setFtype(food.getFtype());
168                 i.setFid(food.getFid());
169                 i.setFprice(food.getFprice());
170                 //小计金额与小计数量
171                 i.setItemNum(1);
172                 i.setItemPrice(food.getFprice()*1);
173                 //添加到集合中
174                 map.put(food.getFid(),i);
175             }
176         }
177         System.out.println("总金额"+car.getSumnum()+car.getSumprice());
178         car.setMap(map);
179         session.setAttribute("car",car);
180         response.sendRedirect("/html/foodcar.jsp");
181     }
182 
183     /**
184      * 菜品列表servlet
185      * @param request
186      * @param response
187      * @throws ServletException
188      * @throws IOException
189      */
190     private void foodlist(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
191         request.setAttribute("flist",foodDao.getFoodList());
192         request.getRequestDispatcher("/html/foodlist.jsp").forward(request,response);
193     }
194 }

 1 package com.food.entity;
 2 
 3 import java.math.BigDecimal;
 4 import java.util.Iterator;
 5 import java.util.Map;
 6 
 7 /**
 8  * 购物车
 9  * 包括每一种菜品小项 总计每一种菜品数量（不包括相同的菜品）、总计金额
10  */
11 public class Car2 {
12     private int sumnum;//总数量数量
13     private int sumprice;//总金额
14     private Map map;//购物车中的每一项（每一个菜品信息）
15 
16     public Car2() {
17     }
18 
19     @Override
20     public String toString() {
21         return "Car2{" +
22                 "sumnum=" + sumnum +
23                 ", sumprice=" + sumprice +
24                 ", map=" + map +
25                 '}';
26     }
27 
28     public int getSumnum() {
29         return sumnum;
30     }
31 
32     public void setSumnum(int sumnum) {
33         this.sumnum = sumnum;
34     }
35 
36     public int getSumprice() {
37         return sumprice;
38     }
39 
40     public void setSumprice(int sumprice) {
41         this.sumprice = sumprice;
42     }
43 
44     public Map getMap() {
45         return map;
46     }
47 
48     /**
49      * 计算总数量与计算总价格
50      * @param map
51      */
52     public void setMap(Map map) {
53         int a = 0;
54         int b = 0;
55         Iterator i = map.values().iterator();
56         while (i.hasNext()){
57             CarItem c = i.next();
58             a+=c.getItemNum();
59             b+=c.getItemPrice();
60         }
61         this.sumnum=a;
62         this.sumprice=b;
63         this.map = map;
64     }
65 }

 1 package com.food.entity;
 2 
 3 import java.io.Serializable;
 4 import java.math.BigDecimal;
 5 
 6 /**
 7  * 购物车中每一个小项
 8  * 小项中包括food类中的 信息 与小计数量、小计金额
 9  */
10 public class CarItem extends Food implements Serializable {
11     private int itemNum;//购物车中小项的菜品数量
12     private int itemPrice;//购物车中小项的菜品价格小计
13 
14     public CarItem() {
15     }
16 
17     @Override
18     public String toString() {
19         return "CarItem{" +
20                 "itemNum=" + itemNum +
21                 ", itemPrice=" + itemPrice +
22                 '}';
23     }
24 
25     public int getItemNum() {
26         return itemNum;
27     }
28 
29     public void setItemNum(int itemNum) {
30         this.itemNum = itemNum;
31     }
32 
33     public int getItemPrice() {
34         return this.getItemNum()*this.getFprice();
35     }
36 
37     public void setItemPrice(int itemPrice) {
38         this.itemPrice = itemPrice;
39     }
40 }

 1 package com.food.entity;
 2 
 3 import java.io.Serializable;
 4 import java.math.BigDecimal;
 5 
 6 /**
 7  * 菜品类
 8  */
 9 public class Food implements Serializable {
10     private int fid;//int(11) NOT NULL购物车id
11     private String fname;//varchar(20) NULL购物车商品名称
12     private String ftype;//varchar(20) NULL购物车中商品类型
13     private String fshop;//varchar(100) NULL购物车中的商品
14     private int fprice;//decimal(9,2) NULL价格
15     private String img;//varchar(30) NULL图片
16 
17     @Override
18     public String toString() {
19         return "Food{" +
20                 "fid=" + fid +
21                 ", fname='" + fname + '\'' +
22                 ", ftype='" + ftype + '\'' +
23                 ", fshop='" + fshop + '\'' +
24                 ", fprice=" + fprice +
25                 ", img='" + img + '\'' +
26                 '}';
27     }
28 
29     public Food() {
30     }
31 
32     public int getFid() {
33         return fid;
34     }
35 
36     public void setFid(int fid) {
37         this.fid = fid;
38     }
39 
40     public String getFname() {
41         return fname;
42     }
43 
44     public void setFname(String fname) {
45         this.fname = fname;
46     }
47 
48     public String getFtype() {
49         return ftype;
50     }
51 
52     public void setFtype(String ftype) {
53         this.ftype = ftype;
54     }
55 
56     public String getFshop() {
57         return fshop;
58     }
59 
60     public void setFshop(String fshop) {
61         this.fshop = fshop;
62     }
63 
64     public int getFprice() {
65         return fprice;
66     }
67 
68     public void setFprice(int fprice) {
69         this.fprice = fprice;
70     }
71 
72     public String getImg() {
73         return img;
74     }
75 
76     public void setImg(String img) {
77         this.img = img;
78     }
79 }

页面效果