Java简化复杂系统调用的门面设计模式

@Data
public class Order {
    private String itemId;
    private int quantity;
    public Order(String itemId, int quantity) {
        this.itemId = itemId;
        this.quantity = quantity;
    }
}

public class InventoryManagement {
    /**
     * 检查库存
     *
     * @param itemId
     * @param quantity
     * @return
     */
    public boolean checkInventory(String itemId, int quantity) {
        System.out.println("检查库存");
        return true;
    }
}
public class OrderManagement {
    /**
     * 创建订单
     *
     * @param itemId
     * @param quanitity
     * @return
     */
    public Order createOrder(String itemId, int quanitity) {
        System.out.println("创建订单");
        return new Order(itemId, quanitity);
    }
}
public class PaymentManagement {
    /**
     * 支付订单
     *
     * @param order
     * @param paymentMethod
     */
    public void makePayment(Order order, String paymentMethod) {
        System.out.println("支付订单");
    }
}

public class OnlineShoppingFacade {
    private InventoryManagement inventoryManagement;
    private OrderManagement orderManagement;
    private PaymentManagement paymentManagement;
    public OnlineShoppingFacade(InventoryManagement inventoryManagement, OrderManagement orderManagement, PaymentManagement paymentManagement) {
        this.inventoryManagement = inventoryManagement;
        this.orderManagement = orderManagement;
        this.paymentManagement = paymentManagement;
    }
    /**
     * 下单操作
     *
     * @param itemId
     * @param quantity
     * @param paymentMenthod
     */
    public void placeOrder(String itemId, int quantity, String paymentMenthod) {
        System.out.println("开始处理下单操作...");
        boolean checkInventory = inventoryManagement.checkInventory(itemId, quantity);
        if (!checkInventory) {
            throw new RuntimeException("库存不足");
        }
        Order order = orderManagement.createOrder(itemId, quantity);
        paymentManagement.makePayment(order, paymentMenthod);
    }
}

public class Demo {
    public static void main(String[] args) {
        OnlineShoppingFacade onlineShoppingFaced = new OnlineShoppingFacade(new InventoryManagement(),
                new OrderManagement(),
                new PaymentManagement());
        onlineShoppingFaced.placeOrder("123",3,"Wechat");
    }
}