基于Java、Jsp实现购物车的功能

先看效果图：

实现代码：

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<jsp:forward page="/index"/>
</body>
</html>

show.jsp

<table border="1" width="450" rules="none" cellspacing="0" cellpadding="0">
   <tr height="50"><td colspan="4" align="center">提供商品如下</td></tr>
   <tr align="center" height="30" bgcolor="lightgrey">
   <td>序号</td>
       <td>名称</td>
       <td>价格(元/斤)</td>
       <td>购买</td>
   </tr>
   <% if(goodslist==null||goodslist.size()==0){ %>
   <tr height="100"><td colspan="4" align="center">没有商品可显示！</td></tr>
   <%
       }
       else{
           for(int i=0;i<goodslist.size();i++){
               GoodsSingle single=(GoodsSingle)goodslist.get(i);
   %>
   <tr height="50" align="center">
       <td><%=single.getName()%></td>
       <td><%=single.getNo()%></td>
       <td><%=single.getPrice()%></td>
       <td><a href="doCar?action=buy&id=<%=i%>">购买</a></td>
   </tr>
   <%
           }
       }
   %>
   <tr height="50">
       <td align="center" colspan="4"><a href="shopcar8.jsp">查看购物车</a></td>
   </tr>
</table>
</body>
</html>

shopcar.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="java.util.ArrayList" %>
<%@ page import="com.shop.GoodsSingle" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
   //获取存储在session中用来存储用户已购买商品的buylist集合对象
   ArrayList buylist=(ArrayList)session.getAttribute("buylist");
   float total=0;                            //用来存储应付金额
%>
<table border="1" width="450" rules="none" cellspacing="0" cellpadding="0">
   <tr height="50"><td colspan="6" align="center">购买的商品如下</td></tr>
   <tr align="center" height="30" bgcolor="lightgrey">
   <td>序号</td>
       <td>名称</td>
       <td>价格(元/斤)</td>
       <td>数量</td>
       <td>总价(元)</td>
       <td>移除(-1/次)</td>
   </tr>
   <%   if(buylist==null||buylist.size()==0){ %>
   <tr height="100"><td colspan="6" align="center">您的购物车为空！</td></tr>
   <%
       }
       else{
           for(int i=0;i<buylist.size();i++){
               GoodsSingle single=(GoodsSingle)buylist.get(i);
               String no = single.getNo();
               String name=single.getName();           //获取商品名称
               float price=single.getPrice();           //获取商品价格
               int num=single.getNum();               //获取购买数量
               //计算当前商品总价，并进行四舍五入
               float money=((int)((price*num+0.05f)*10))/10f;
               total+=money;                            //计算应付金额
   %>
   <tr align="center" height="50">
       <td><%=name%></td>
       <td><%=no%></td>
       <td><%=price%></td>
       <td><%=num%></td>
       <td><%=money%></td>
       <td><a href="doCar?action=remove&name=<%=single.getName() %>">移除</a></td>
   </tr>
   <%
           }
       }
   %>
   <tr height="50" align="center"><td colspan="6">应付金额：<%=total%></td></tr>
   <tr height="50" align="center">
       <td colspan="3"><a href="show8.jsp">继续购物</a></td>
       <td colspan="4"><a href="doCar?action=clear">清空购物车</a></td>
   </tr>
</table>
</body>
</html>

BuyServlet.java

package com.shop;

import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.shop.MyTools;
import com.shop.ShopCar;
import com.shop.GoodsSingle;

public class BuyServlet extends HttpServlet {

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       doPost(request,response);
   }

   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       String action=request.getParameter("action");   //获取action参数值
       if(action==null)
           action="";
       if(action.equals("buy"))                   //触发了“购买”请求
           buy(request,response);                       //调用buy()方法实现商品的购买
       if(action.equals("remove"))                   //触发了“移除”请求
           remove(request,response);                   //调用remove()方法实现商品的移除
       if(action.equals("clear"))                   //触发了“清空购物车”请求
           clear(request,response);                   //调用clear()方法实现购物车的清空
   }
   //实现购买商品的方法
   protected void buy(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       HttpSession session=request.getSession();
       String strId=request.getParameter("id");       //获取触发“购买”请求时传递的id参数，该参数存储的是商品在goodslist对象中存储的位置
       int id=MyTools.strToint(strId);

       ArrayList goodslist=(ArrayList)session.getAttribute("goodslist");
       GoodsSingle single=(GoodsSingle)goodslist.get(id);

       ArrayList buylist=(ArrayList)session.getAttribute("buylist");       //从session范围内获取存储了用户已购买商品的集合对象
       if(buylist==null)
           buylist=new ArrayList();

       ShopCar myCar=new ShopCar();
       myCar.setBuylist(buylist);                        //将buylist对象赋值给ShopCar类实例中的属性
       myCar.addItem(single);                           //调用ShopCar类中addItem()方法实现商品添加操作

       session.setAttribute("buylist",buylist);
       response.sendRedirect("show8.jsp");               //将请求重定向到show.jsp页面
   }
   //实现移除商品的方法
   protected void remove(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       HttpSession session=request.getSession();
       ArrayList buylist=(ArrayList)session.getAttribute("buylist");

       String name=request.getParameter("name");
       ShopCar myCar=new ShopCar();
       myCar.setBuylist(buylist);                       //将buylist对象赋值给ShopCar类实例中的属性
       myCar.removeItem(MyTools.toChinese(name));       //调用ShopCar类中removeItem ()方法实现商品移除操作

       response.sendRedirect("shopcar8.jsp");
   }
   //实现清空购物车的方法
   protected void clear(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       HttpSession session=request.getSession();
       ArrayList buylist=(ArrayList)session.getAttribute("buylist");           //从session范围内获取存储了用户已购买商品的集合对象
       buylist.clear();                                                       //清空buylist集合对象，实现购物车清空的操作

       response.sendRedirect("shopcar8.jsp");
   }
}

GoodsSingle.java

package com.shop;

public class GoodsSingle {
   private String no;
   public String getNo() {
       return no;
   }
   public void setNo(String no) {
       this.no = no;
   }
   private String name;                       //保存商品名称
   private float price;                       //保存商品价格
   private int num;                           //保存商品购买数量

   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   public int getNum() {
       return num;
   }
   public void setNum(int num) {
       this.num = num;
   }
   public float getPrice() {
       return price;
   }
   public void setPrice(float price) {
       this.price = price;
   }
}

IndexServlet.java

package com.shop;

public class IndexServlet extends HttpServlet {
   private static ArrayList goodslist=new ArrayList();
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       doPost(request,response);
   }
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       HttpSession session=request.getSession();
       session.setAttribute("goodslist",goodslist);
       response.sendRedirect("show8.jsp");
   }
   static{                                       //静态代码块
       String[] no={"苹果","香蕉","梨","橘子"};
       String[] names={"A","B","C","D"};
       float[] prices={2.8f,3.1f,2.5f,2.3f};
       for(int i=0;i<4;i++){
           GoodsSingle single=new GoodsSingle();
           single.setNo(no[i]);
           single.setName(names[i]);
           single.setPrice(prices[i]);
           single.setNum(1);
           goodslist.add(single);
       }
   }
}

MyTools.java

package com.shop;

import java.io.UnsupportedEncodingException;

public class MyTools {
   public static int strToint(String str){           //将String型数据转换为int型数据的方法
       if(str==null||str.equals(""))
           str="0";
       int i=0;
       try{
           i=Integer.parseInt(str);
       }catch(NumberFormatException e){
           i=0;
           e.printStackTrace();
       }
       return i;
   }
   public static String toChinese(String str){       //进行转码操作的方法
       if(str==null)
           str="";
       try {
           str=new String(str.getBytes("ISO-8859-1"),"UTF-8");
       } catch (UnsupportedEncodingException e) {
           str="";
           e.printStackTrace();
       }
       return str;
   }
}

ShopCar.java

package com.shop;

import java.util.ArrayList;
import com.shop.GoodsSingle;

public class ShopCar {
   private ArrayList buylist=new ArrayList();                                   //用来存储购买的商品
   public void setBuylist(ArrayList buylist) {
       this.buylist = buylist;
   }
   /**
   * @功能向购物车中添加商品
   * @参数 single为GoodsSingle类对象，封装了要添加的商品信息
   */
   public void addItem(GoodsSingle single){
       if(single!=null){
           if(buylist.size()==0){                                               //如果buylist中不存在任何商品
               GoodsSingle temp=new GoodsSingle();
               temp.setNo(single.getNo());
               temp.setName(single.getName());
               temp.setPrice(single.getPrice());
               temp.setNum(single.getNum());
               buylist.add(temp);                                               //存储商品
           }
           else{                                                               //如果buylist中存在商品
               int i=0;
               for(;i<buylist.size();i++){                                       //遍历buylist集合对象，判断该集合中是否已经存在当前要添加的商品
                   GoodsSingle temp=(GoodsSingle)buylist.get(i);               //获取buylist集合中当前元素
                   if(temp.getName().equals(single.getName())){               //判断从buylist集合中获取的当前商品的名称是否与要添加的商品的名称相同
                       //如果相同，说明已经购买了该商品，只需要将商品的购买数量加1
                       temp.setNum(temp.getNum()+1);                           //将商品购买数量加1
                       break;                                                   //结束for循环
                   }
               }
               if(i>=buylist.size()){                                           //说明buylist中不存在要添加的商品
                   GoodsSingle temp=new GoodsSingle();
                   temp.setNo(single.getNo());
                   temp.setName(single.getName());
                   temp.setPrice(single.getPrice());
                   temp.setNum(single.getNum());
                   buylist.add(temp);                                           //存储商品
               }
           }
       }
   }
   /**
   * @功能从购物车中移除指定名称的商品
   * @参数 name表示商品名称
   */
   public void removeItem(String name){
       for(int i=0;i<buylist.size();i++){                           //遍历buylist集合，查找指定名称的商品
           GoodsSingle temp=(GoodsSingle)buylist.get(i);        //获取集合中当前位置的商品
           if(temp.getName().equals(name)){                       //如果商品的名称为name参数指定的名称
               if(temp.getNum()>1){                               //如果商品的购买数量大于1
                   temp.setNum(temp.getNum()-1);                   //则将购买数量减1
                   break;                                  //结束for循环
               }
               else if(temp.getNum()==1){                           //如果商品的购买数量为1
                   buylist.remove(i);                           //从buylist集合对象中移除该商品
               }
           }
       }
   }
}