（1） 利用session实现购物车中的物品添加。
（2）使用servlet实现添加物品的功能（交互层）。
（3）一共有三个界面。第一个用来显示物品的列表的页面，第二个用来显示添物品的界面，第三个用来显示添加到购物车的信息页面。
（1）物品列表页面：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> <a href="<%=request.getContextPath()%>/shopping.pdo?pname='LENOVO R7'">联想拯救者R7</a> <br><br> <a href="<%=request.getContextPath()%>/shopping.pdo?pname='LENOVO R8'">联想拯救者R8</a> <br><br> <a href="<%=request.getContextPath()%>/shopping.pdo?pname='LENOVO R9'">联想拯救者R9</a> <br><br> <a href="<%=request.getContextPath()%>/shopping.pdo?pname='LENOVO R10'">联想拯救者R10</a> <br><br> </body> </html>
（2）添加购物车页面：producttails.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>
<%
String pname = (String)request.getAttribute("p");
out.println(pname);
%>
<br><br>
拿到其他的......该产品的详细参数
<br><br>
<a style="display: block;width: 100px ; height: 35px ;line-height :35px; text-decoration : none;background: red; color:#fff ;text-align: center;" href="<%=request.getContextPath() %>/addcart.pdo?pname=<%=pname %>" >加入购物车</a>
</body>
</html>（3）显示添加成功后的信息页面：shoppingcart.jsp
<%@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>
<%
List<String> products = (List<String>)session.getAttribute("car");
for(String s: products){
out.print(s+"<br><br>");
}
%>
</body>
</html>（4）交互层：ShopController.java
package com.controller;
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;
/**
* Servlet implementation class ShopController
*/
@WebServlet(urlPatterns = {"*.pdo"})
public class ShopController extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ShopController() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置字符集
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setCharacterEncoding("text/html; charset=utf-8");
//在这个方法里边处理所有的增删改查的功能
String mn = request.getServletPath();
mn = mn.substring(1);
mn = mn.substring(0 , mn.length()-4);
//利用反射
try {
//获取方法名，并且根据具体的去调用下边的方法
Method method = this.getClass().getDeclaredMethod(mn,HttpServletRequest.class , HttpServletResponse.class);
method.invoke(this,request,response);
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
private void shopping (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置字符集
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setCharacterEncoding("text/html; charset=utf-8");
String pname = request.getParameter("pname");
request.setAttribute("p", pname);
request.getRequestDispatcher("/producttails.jsp").forward(request, response);;
}
private void addcart (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置字符集
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setCharacterEncoding("text/html; charset=utf-8");
String pname = request.getParameter("pname");
//添加购物车
HttpSession session = request.getSession(true);
List<String> products = (List<String>)session.getAttribute("car");
if(products == null) {
products = new ArrayList<>();
}
//把添加的物品放入List集合
products.add(pname);
//放入session中表示添加成功
session.setAttribute("car", products);
//response.getWriter().print("添加成功！");
response.sendRedirect(request.getContextPath() + "/shoppingcart.jsp");
}
}
