使用session做的购物车

温故而知新。工程结构：

public class Product {

    private int id;
    private String name;
    private double price;

    public Product(int id, String name, double price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Product{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}

import com.yz.bean.Product;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.*;

/**
 * @description:
 * @author: yz
 * @create: 2018/11/7 11:06
 */
@Controller
public class ProductController {

    private static List<Product> list = new ArrayList<Product>();

    // 只会执行一次，当类的字节码被加载到jvm的时候，只会执行一次
    static {
        list.add(new Product(1,"小米5",1999));   //1
        list.add(new Product(2,"海尔冰箱",2999)); //2
        list.add(new Product(3,"vivo8",3999)); //3
        list.add(new Product(4,"iphon9",6999));
        list.add(new Product(5,"联想鼠标垫",50));
    }

    // 显示商品列表
    @RequestMapping("listProduct")
    public String listProduct(Model model){
        // 准备商品
        // 存商品
        model.addAttribute("list",list);
        return "list";
    }
    // 添加商品到购物车中,需要商品的编号
    @RequestMapping("addToCart")
    public String addToCart(HttpServletRequest request , HttpServletResponse response, int id){

        System.out.println("id:"+id);
        // 获取sessoin
        HttpSession session = request.getSession();
        // 获取商品对象
        Product product = list.get(id - 1);
        // 存储到购物车
        Map<Product , Integer> cartMap = (Map<Product, Integer>) session.getAttribute("cartMap");
        if(cartMap == null){
            cartMap = new HashMap<Product , Integer>();
        }

        if(cartMap.containsKey(product)){
            // 有这件商品，原来的数量+1
            cartMap.put(product, cartMap.get(product)+1);
        }else {
            cartMap.put(product,1);
        }

        // 把购物车存到session中去
        session.setAttribute("cartMap",cartMap);
        System.out.println("添加购物车完毕，要跳转到中转页面了~");
        // 为了让购物车存的时间更长久一点，现在需要手动设置cookie
        Cookie cookie = new Cookie("JSESSIONID" , session.getId());
        cookie.setMaxAge(60*60*24*7);
        response.addCookie(cookie);

        //4. 跳转页面  当前的请求是从模板页面发送出来的，所以这里也认为是跑到模板页面去了。
        return "redirect:transfer.html";
    }

    //跳转到购物车的页面
    @RequestMapping("toCart")
    public String toCart(){

        return "cart";
    }
}

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @description:
 * @author: yz
 * @create: 2018/11/7 11:03
 */
@SpringBootApplication
public class CartApp {
    public static void main(String [] args){
        SpringApplication.run(CartApp.class,args);
    }
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

    <h2><a href="listProduct">开始购物</a></h2>
</body>
</html>

transfer.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

    <!--继续回到商品列表的方法去u-->
    <h2><a href="listProduct">继续购物</a></h2><br><br>

    <h2><a href="toCart">去购物车结算</a></h2><br><br>

</body>
</html>

cart.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org" >
<head>
    <meta charset="UTF-8"/>
    <title>购物车</title>
</head>
<body>

    <table>

        <thead>
            <td width="100px">编号</td>
            <td width="100px">名称</td>
            <td width="100px">价格</td>
            <td width="100px">数量</td>
            <td width="100px">小计</td>
        </thead>

        <tbody>

            <tr th:each="entry:${session.cartMap}">
                <td th:text="${entry.key.id}">1</td>
                <td th:text="${entry.key.name}">2</td>
                <td th:text="${entry.key.price}">3</td>
                <td th:text="${entry.value}">3</td>
                <td th:text="${entry.key.price * entry.value}">4</td>
            </tr>

        </tbody>

    </table>

</body>
</html>

list.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org" >
<head>
    <meta charset="UTF-8"/>
    <title>Title</title>
</head>
<body>

    <h2>商品列表</h2>

    <table>

        <thead>
            <td width="100px">编号</td>
            <td width="100px">名称</td>
            <td width="100px">价格</td>
            <td width="100px">操作</td>
        </thead>

        <tbody>

            <tr th:each="p:${list}">
                <td th:text="${p.id}">1</td>
                <td th:text="${p.name}">小米99</td>
                <td th:text="${p.price}">1999</td>

                <td><a th:href="@{addToCart(id=${p.id})}">加入购物车</a></td>
                <!--<td><a th:href="@{addToCart(id=${p.id},name=${p.name})}">加入购物车</a></td>-->

                <!--th:href="@{/product/comments(prodId=${prod.id})}"
                addToCart?id=1&name=aaa&age=123123
                th:href="@{addToCart(id=${p.id})}"-->
            </tr>

        </tbody>

    </table>

</body>
</html>

build.gradle

plugins {
    id 'java'
}

group 'com.yz'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile("org.springframework.boot:spring-boot-starter-web:1.5.10.RELEASE")
    compile("org.thymeleaf:thymeleaf-spring4:2.1.4.RELEASE")
}

效果：

使用session做的购物车

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