购物车的简单实现

打开eclipse建立，建立Dynamic Web Project 工程命名 shoppingcart，注意需要配置xml文件。

工程目录建立如下图：
工程结构

ShopController.java



import java.io.IOException;
import java.lang.reflect.Method;
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 javax.servlet.http.HttpSession;

//另一种配置方法，该方法配置xml需要注意，该功能不能被禁用
@WebServlet(urlPatterns= {"*.pdo"})
public final class ShopController extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @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 {
        //解决中文乱码
                req.setCharacterEncoding("UTF-8");
                resp.setCharacterEncoding("UTF-8");
                String mn = req.getServletPath();
                mn = mn.substring(1);
                mn = mn.substring(0, mn.length()-4);
                //利用反射
                try {
                    Method method = this.getClass().getDeclaredMethod(mn, HttpServletRequest.class, HttpServletResponse.class);
                    method.invoke(this, req, resp);
                } catch (Exception e) {
                    e.printStackTrace();
                } 
    }

    @SuppressWarnings("unused")
    private void shopping(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String pname = req.getParameter("pname");//提交过来商品信息的获取
        req.setAttribute("pname", pname);
        req.getRequestDispatcher("/productdetails.jsp").forward(req, resp);//转发
    }

    @SuppressWarnings("unused")
    private void addcar(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String pname = req.getParameter("pname");
        HttpSession session = req.getSession(true);
        @SuppressWarnings("unchecked")
        List<String> list = (List<String>)session.getAttribute("car");
        if(null == list) {
            list = new ArrayList<>();
        }
        //添加到购物车
        list.add(pname);
        session.setAttribute("car", list);
        //resp.setCharacterEncoding("UTF-8");
        //resp.getWriter().println("添加成功！");
        resp.sendRedirect(req.getContextPath() + "/productcars.jsp");
    }
}

注意

//另一种配置方法，该方法配置xml需要注意，该功能不能被禁用
@WebServlet(urlPatterns= {“*.pdo”})
配置更简便

productlist.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>
    <br><br>
    <!-- 提交到接收pdo的servlet中 -->
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=联想笔记本">联想笔记本</a>
    <br><br>
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=华硕主板">华硕主板</a>
    <br><br>
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=金士顿优盘">金士顿优盘</a>
    <br><br>
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=飞行棋">飞行棋</a>
    <br><br>
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=TCL显示屏">TCL显示屏</a>
    <br><br>
    <a href="<%=request.getContextPath()%>/shopping.pdo?pname=火星土豆">火星土豆</a>
    <br><br>

</body>
</html>

productdetails.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>
    <br><br>
    该产品的详细信息。
    <br><br>

    <form action="<%=request.getContextPath()%>/addcar.pdo?pname=<%=request.getAttribute("pname")%>" ><!-- 提交一次 -->
        <input type="hidden" name="pname" value="<%=request.getAttribute("pname") %>">  <!-- 再次提交，覆盖之前的 因为都是pname -->
        <input style="width: 120px; height: 30px; background: red; color: #fff;" type="submit" value="加入购物车" >
    </form>

    <br><br><br><br>

    <a style="display: block; width: 120px; height: 30px; background: red; color: #fff;">加入购物车</a>

</body>
</html>

注意代码中哟两次提交，我们窒息要提交一次就可以。

productcars.jsp

<%@page import="javafx.scene.control.Alert"%>
<%@page import="java.util.List"%>
<%@ 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>
    <%
        @SuppressWarnings("unchecked")
        List<String> list = (List<String>)session.getAttribute("car");
        if(list != null && list.size() > 0) {
            for(String str : list) {
                out.print("<br><br>" + str);
            }
        }
    %>
</body>
</html>

结果测试

打开你的浏览器，输入网址：
http://localhost:8080/shoppingcart/productlist.jsp
进行测试。

代码

代码内容