用springboot,在表user（uid，uname,upwd）表commodity（cid,cname,cprice）表cart(cartid,cid,uid,cnum,cartprice,cartselected),表orders(oid,uid,cid,ocondition,oprice,ocount)的基础上实现购物车功能(加入购物车，加减商品数量，计算选中商品总价)，加入购物车需要写入cart,提交订单要写入orders,计算总价需要根据选中商品数量和价格更新，代码包括html,entity,repository,service,controller

好的，下面是实现购物车功能的代码。

1. 实体类代码

User.java

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer uid;

    private String uname;

    private String upwd;

    // getter and setter
}

Commodity.java

@Entity
@Table(name = "commodity")
public class Commodity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer cid;

    private String cname;

    private Float cprice;

    // getter and setter
}

Cart.java

@Entity
@Table(name = "cart")
public class Cart {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer cartid;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "uid")
    private User user;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "cid")
    private Commodity commodity;

    private Integer cnum;

    private Float cartprice;

    private Boolean cartselected;

    // getter and setter
}

Orders.java

@Entity
@Table(name = "orders")
public class Orders {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer oid;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "uid")
    private User user;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "cid")
    private Commodity commodity;

    private String ocondition;

    private Float oprice;

    private Integer ocount;

    // getter and setter
}

2. Repository代码

UserRepository.java

@Repository
public interface UserRepository extends JpaRepository<User, Integer> {
}

CommodityRepository.java

@Repository
public interface CommodityRepository extends JpaRepository<Commodity, Integer> {
}

CartRepository.java

@Repository
public interface CartRepository extends JpaRepository<Cart, Integer> {
    List<Cart> findByUserAndCartselected(User user, Boolean cartselected);
}

OrdersRepository.java

@Repository
public interface OrdersRepository extends JpaRepository<Orders, Integer> {
}

3. Service代码

UserService.java

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public User getUserById(Integer uid) {
        return userRepository.findById(uid).orElse(null);
    }
}

CommodityService.java

@Service
public class CommodityService {
    @Autowired
    private CommodityRepository commodityRepository;

    public Commodity getCommodityById(Integer cid) {
        return commodityRepository.findById(cid).orElse(null);
    }
}

CartService.java

@Service
public class CartService {
    @Autowired
    private CartRepository cartRepository;

    public void addToCart(User user, Commodity commodity, Integer cnum) {
        Cart cart = cartRepository.findByUserAndCommodity(user, commodity);
        if (cart == null) {
            cart = new Cart();
            cart.setUser(user);
            cart.setCommodity(commodity);
            cart.setCnum(cnum);
            cart.setCartprice(commodity.getCprice() * cnum);
            cart.setCartselected(true);
        } else {
            cart.setCnum(cart.getCnum() + cnum);
            cart.setCartprice(cart.getCartprice() + commodity.getCprice() * cnum);
        }
        cartRepository.save(cart);
    }

    public List<Cart> getCartList(User user) {
        return cartRepository.findByUserAndCartselected(user, true);
    }

    public void updateCart(Cart cart) {
        cartRepository.save(cart);
    }

    public void deleteCart(Integer cartid) {
        cartRepository.deleteById(cartid);
    }
}

OrdersService.java

@Service
public class OrdersService {
    @Autowired
    private OrdersRepository ordersRepository;

    public void addOrder(User user, Commodity commodity, Integer ocount) {
        Orders orders = new Orders();
        orders.setUser(user);
        orders.setCommodity(commodity);
        orders.setOcondition("待发货");
        orders.setOprice(commodity.getCprice() * ocount);
        orders.setOcount(ocount);
        ordersRepository.save(orders);
    }
}

4. Controller代码

UserController.java

@Controller
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/user/{uid}")
    @ResponseBody
    public User getUserById(@PathVariable Integer uid) {
        return userService.getUserById(uid);
    }
}

CommodityController.java

@Controller
public class CommodityController {
    @Autowired
    private CommodityService commodityService;

    @GetMapping("/commodity/{cid}")
    @ResponseBody
    public Commodity getCommodityById(@PathVariable Integer cid) {
        return commodityService.getCommodityById(cid);
    }
}

CartController.java

@Controller
public class CartController {
    @Autowired
    private CartService cartService;

    @Autowired
    private UserService userService;

    @Autowired
    private CommodityService commodityService;

    @PostMapping("/cart/add")
    public String addToCart(Integer uid, Integer cid, Integer cnum) {
        User user = userService.getUserById(uid);
        Commodity commodity = commodityService.getCommodityById(cid);
        cartService.addToCart(user, commodity, cnum);
        return "redirect:/cart/list?uid=" + uid;
    }

    @GetMapping("/cart/list")
    public String getCartList(Integer uid, Model model) {
        User user = userService.getUserById(uid);
        List<Cart> cartList = cartService.getCartList(user);
        Float totalPrice = cartList.stream().map(Cart::getCartprice).reduce(0f, Float::sum);
        model.addAttribute("cartList", cartList);
        model.addAttribute("totalPrice", totalPrice);
        return "cart";
    }

    @PostMapping("/cart/update")
    @ResponseBody
    public String updateCart(Integer cartid, Integer cnum) {
        Cart cart = cartService.getCartById(cartid);
        if (cart != null) {
            cart.setCnum(cnum);
            cart.setCartprice(cart.getCommodity().getCprice() * cnum);
            cartService.updateCart(cart);
            return "success";
        }
        return "fail";
    }

    @PostMapping("/cart/delete")
    @ResponseBody
    public String deleteCart(Integer cartid) {
        cartService.deleteCart(cartid);
        return "success";
    }
}

OrdersController.java

@Controller
public class OrdersController {
    @Autowired
    private OrdersService ordersService;

    @Autowired
    private UserService userService;

    @Autowired
    private CommodityService commodityService;

    @PostMapping("/orders/add")
    public String addOrder(Integer uid, Integer cid, Integer ocount) {
        User user = userService.getUserById(uid);
        Commodity commodity = commodityService.getCommodityById(cid);
        ordersService.addOrder(user, commodity, ocount);
        return "redirect:/cart/list?uid=" + uid;
    }
}

5. 页面代码

cart.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>购物车</title>
    <script src="https://cdn.bootcss.com/jquery/3.5.1/jquery.min.js"></script>
</head>
<body>
<h1>购物车</h1>
<table border="1">
    <thead>
    <tr>
        <th>商品名称</th>
        <th>单价</th>
        <th>数量</th>
        <th>小计</th>
        <th>操作</th>
    </tr>
    </thead>
    <tbody>
    <form th:each="cart : ${cartList}">
        <tr>
            <td th:text="${cart.commodity.cname}"></td>
            <td th:text="${cart.commodity.cprice}"></td>
            <td>
                <input type="number" name="cnum" th:value="${cart.cnum}" onchange="updateCart(this, [[${cart.cartid}]])">
            </td>
            <td th:text="${cart.cartprice}"></td>
            <td>
                <button type="button" onclick="deleteCart([[${cart.cartid}]])">删除</button>
            </td>
        </tr>
    </form>
    </tbody>
    <tfoot>
    <tr>
        <td colspan="3">总计：</td>
        <td th:text="${totalPrice}"></td>
        <td><button type="button" onclick="submitOrders([[${uid}]])">提交订单</button></td>
    </tr>
    </tfoot>
</table>
<script>
    function updateCart(obj, cartid) {
        var cnum = $(obj).val();
        $.ajax({
            url: "/cart/update",
            type: "post",
            dataType: "text",
            data: {
                cartid: cartid,
                cnum: cnum
            },
            success: function (data) {
                if (data == "success") {
                    location.reload();
                } else {
                    alert("更新购物车失败");
                }
            },
            error: function () {
                alert("更新购物车失败");
            }
        });
    }

    function deleteCart(cartid) {
        $.ajax({
            url: "/cart/delete",
            type: "post",
            dataType: "text",
            data: {
                cartid: cartid
            },
            success: function (data) {
                if (data == "success") {
                    location.reload();
                } else {
                    alert("删除购物车失败");
                }
            },
            error: function () {
                alert("删除购物车失败");
            }
        });
    }

    function submitOrders(uid) {
        var cartList = [];
        $('input[name="cartid"]:checked').each(function () {
            cartList.push($(this).val());
        });
        if (cartList.length == 0) {
            alert("请选择要购买的商品");
            return;
        }
        $.ajax({
            url: "/orders/add",
            type: "post",
            dataType: "text",
            data: {
                uid: uid,
                cid: cartList[0],
                ocount: cartList.length
            },
            success: function (data) {
                if (data == "success") {
                    location.href = "/orders/list?uid=" + uid;
                } else {
                    alert("提交订单失败");
                }
            },
            error: function () {
                alert("提交订单失败");
            }
        });
    }
</script>
</body>
</html>

orders.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>订单列表</title>
</head>
<body>
<h1>订单列表</h1>
<table border="1">
    <thead>
    <tr>
        <th>订单号</th>
        <th>商品名称</th>
        <th>单价</th>
        <th>数量</th>
        <th>总价</th>
        <th>状态</th>
    </tr>
    </thead>
    <tbody>
    <form th:each="orders : ${ordersList}">
        <tr>
            <td th:text="${orders.oid}"></td>
            <td th:text="${orders.commodity.cname}"></td>
            <td th:text="${orders.commodity.cprice}"></td>
            <td th:text="${orders.ocount}"></td>
            <td th:text="${orders.oprice}"></td>
            <td th:text="${orders.ocondition}"></td>
        </tr>
    </form>
    </tbody>
</table>
</body>
</html>

至此，基于Spring Boot实现购物车功能的代码就介绍完了。