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'''
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在书城的业务背景中，外观模式（Facade Pattern）可以用于提供一个简化的接口，以隐藏系统的复杂性。
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假设书城提供了多种服务，如用户认证、购物车管理、订单处理等，外观模式可以将这些服务整合到一个统一的接口中，
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使客户端能够更方便地使用这些服务。
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下面是一个简单的实现代码示例，展示如何使用外观模式来整合书城的不同服务：
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'''
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# 用户服务类
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class UserService:
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def authenticate(self, username, password):
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# 这里是用户认证的实现代码
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print(f"Authenticating user {username}...")
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return True # 假设认证总是成功
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# 购物车服务类
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class CartService:
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def add_to_cart(self, user_id, book_id):
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# 这里是将书籍添加到购物车的实现代码
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print(f"User {user_id} added book {book_id} to the cart.")
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def remove_from_cart(self, user_id, book_id):
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# 这里是从购物车中移除书籍的实现代码
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print(f"User {user_id} removed book {book_id} from the cart.")
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# 订单服务类
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class OrderService:
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def create_order(self, user_id, cart_items):
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# 这里是创建订单的实现代码
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print(f"Creating order for user {user_id} with items {cart_items}...")
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return "OrderID123" # 假设返回一个订单ID
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# 书城外观类
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class BookstoreFacade:
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def __init__(self):
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self.user_service = UserService()
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self.cart_service = CartService()
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self.order_service = OrderService()
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def login_and_add_to_cart(self, username, password, book_id):
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if self.user_service.authenticate(username, password):
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print("Login successful.")
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# 假设用户ID为1（实际应用中应该通过认证服务获取）
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user_id = 1
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self.cart_service.add_to_cart(user_id, book_id)
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else:
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print("Login failed.")
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def checkout(self, username, password):
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if self.user_service.authenticate(username, password):
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print("Login successful.")
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# 假设用户ID为1（实际应用中应该通过认证服务获取）
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user_id = 1
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# 假设获取购物车项目的方法存在（实际应用中需要实现）
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cart_items = self.get_cart_items(user_id)
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if cart_items:
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order_id = self.order_service.create_order(user_id, cart_items)
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print(f"Order created with ID: {order_id}")
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else:
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print("Your cart is empty.")
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else:
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print("Login failed.")
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def get_cart_items(self, user_id):
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# 这里应该有一个方法来获取购物车中的项目，但为了简化示例，我们直接返回一个列表
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return [1, 2, 3] # 假设的书籍ID列表
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# 客户端代码
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if __name__ == "__main__":
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bookstore = BookstoreFacade()
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# 用户登录并添加书籍到购物车
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bookstore.login_and_add_to_cart("alice", "password123", "book456")
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# 用户结账创建订单
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bookstore.checkout("alice", "password123")
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