编写一个基于MVC的网络点餐系统代码

这是一个简单的基于MVC的网络点餐系统代码示例，使用Java语言和Spring框架实现：

Model部分：

public class MenuItem {
    private int id;
    private String name;
    private double price;

    // getters and setters
}

public class OrderItem {
    private MenuItem menuItem;
    private int quantity;

    // getters and setters
}

public class Order {
    private List<OrderItem> orderItems;
    private double totalPrice;

    // getters and setters
}

View部分：

// 菜单页面
<table>
  <tr>
    <th>ID</th>
    <th>名称</th>
    <th>价格</th>
    <th>数量</th>
    <th>添加</th>
  </tr>
  <c:forEach items="${menuItems}" var="menuItem">
    <tr>
      <td>${menuItem.id}</td>
      <td>${menuItem.name}</td>
      <td>${menuItem.price}</td>
      <td><input type="number" name="quantity_${menuItem.id}" value="0"></td>
      <td><button onclick="addToCart(${menuItem.id})">添加到购物车</button></td>
    </tr>
  </c:forEach>
</table>

// 购物车页面
<table>
  <tr>
    <th>ID</th>
    <th>名称</th>
    <th>数量</th>
    <th>单价</th>
    <th>小计</th>
  </tr>
  <c:forEach items="${orderItems}" var="orderItem">
    <tr>
      <td>${orderItem.menuItem.id}</td>
      <td>${orderItem.menuItem.name}</td>
      <td>${orderItem.quantity}</td>
      <td>${orderItem.menuItem.price}</td>
      <td>${orderItem.menuItem.price * orderItem.quantity}</td>
    </tr>
  </c:forEach>
  <tr>
    <td colspan="4">总价</td>
    <td>${totalPrice}</td>
  </tr>
  <tr>
    <td colspan="5"><button onclick="submitOrder()">提交订单</button></td>
  </tr>
</table>

Controller部分：

@Controller
@RequestMapping("/menu")
public class MenuController {
    @Autowired
    private MenuService menuService;

    @GetMapping("")
    public String showMenu(Model model) {
        List<MenuItem> menuItems = menuService.getAllMenuItems();
        model.addAttribute("menuItems", menuItems);
        return "menu";
    }
}

@Controller
@RequestMapping("/cart")
public class CartController {
    @Autowired
    private OrderService orderService;

    @GetMapping("")
    public String showCart(Model model) {
        Order order = orderService.getCurrentOrder();
        model.addAttribute("orderItems", order.getOrderItems());
        model.addAttribute("totalPrice", order.getTotalPrice());
        return "cart";
    }

    @PostMapping("/add-to-cart")
    public String addToCart(@RequestParam int menuItemId, @RequestParam int quantity) {
        orderService.addToCart(menuItemId, quantity);
        return "redirect:/cart";
    }

    @PostMapping("/submit-order")
    public String submitOrder() {
        orderService.submitOrder();
        return "redirect:/menu";
    }
}

Service部分：

@Service
public class MenuService {
    public List<MenuItem> getAllMenuItems() {
        // 获取所有菜单项
    }
}

@Service
@SessionScope
public class OrderService {
    private Order currentOrder;

    public Order getCurrentOrder() {
        if (currentOrder == null) {
            currentOrder = new Order();
        }
        return currentOrder;
    }

    public void addToCart(int menuItemId, int quantity) {
        MenuItem menuItem = getMenuService().getMenuItemById(menuItemId);
        OrderItem orderItem = new OrderItem(menuItem, quantity);
        getCurrentOrder().addOrderItem(orderItem);
    }

    public void submitOrder() {
        // 将当前订单提交到数据库中，并清空当前订单
    }
}

这只是一个简单的示例，实际的网络点餐系统可能需要更复杂的逻辑和功能。