实现购物车

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;

public class ListBookServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        Collection books = BookDB.getAll();
        out.write("本站提供的图书有：
");
        for(book bok:books){
            String url = "/demo_war_exploded/xax?id="+ bok.getId();
            out.write(bok.getName()+"点击购买
");
        }
    }
}

import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;

public class fx extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        //变量cart引用用户的购物车
        List cart = null;
        //变量pruFlag标记用户是否买过商品
        boolean purFlag = true;
        //获取用户的session
        HttpSession session = request.getSession(false);
        //如果session为null，pruFlag置为false
        if(session == null){
            purFlag = false;
        }else {
            //获得用户购物车
            cart = (List)session.getAttribute("cart");
            //如果用的购物车为null，pruFlag置为false
            if(cart == null){
                purFlag = false;
            }
        }
        if(!purFlag){
            out.write("对不起！您没有购买任何商品!
");
        }else {
            //否则显示用户购买图书的信息
            out.write("您购买的图书有：
");
            double price = 0;
            for(book bok:cart){
                out.write(bok.getName()+"
");
            }
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        this.doGet(request,response);
    }

}

import java.io.Serializable;

public class book implements Serializable {

    private static final long serialVersionUID = 1L;
    private String id;
    private String name;
    public book(){}

    public book(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

import java.util.Collection;
import java.util.linkedHashMap;
import java.util.Map;

public class BookDB {

    private static Map books = new linkedHashMap<>();
    static {
        books.put("1",new book("1","javaweb开发"));
        books.put("2",new book("2","jdbc开发"));
        books.put("3",new book("3","java开发"));
        books.put("4",new book("4","structs开发"));
        books.put("5",new book("5","spring开发"));
    }
    //获得所有图书
    public static Collection getAll(){
        return books.values();
    }
    //根据指定的id获得图书
    public static book getBook(String id){
        return books.get(id);
    }
}

import javax.servlet.http.*;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class ax  extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String id = request.getParameter("id");
        if(id == null){
            String url = "/demo_war_exploded/lbs";
            response.sendRedirect(url);
            return;
        }
        book Book = BookDB.getBook(id);
        HttpSession session = request.getSession();
        //从Session对象中获得用户的购物车
        List cart = (List) session.getAttribute("cart");
        if(cart == null){
            //首次购买，为用户创建一个购物车
            cart = new ArrayList<>();
            //将购物车存入Session对象
            session.setAttribute("cart",cart);
        }
        cart.add(Book);
        cookie cookie = new cookie("JSESSIONID",session.getId());
        cookie.setMaxAge(60*30);
        cookie.setPath("/demo");
        response.addcookie(cookie);
        //重定向到购物车页面
        response.sendRedirect("/demo_war_exploded/xfx");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        this.doGet(request,response);
    }

}

    
        companyName
        fx
    
    
        address
        ty
    
    
        fx
        fx
    
    
        fx
        /xfx
    
    
        ax
        ax
    
    
        ax
        /xax
    
    
        ListBookServlet
        ListBookServlet
    
    
        ListBookServlet
        /lbs