\u4ee3\u7801\u91cd\u6784\u662f\u6539\u5584\u4ee3\u7801\u7ed3\u6784\u800c\u4e0d\u6539\u53d8\u5916\u90e8\u884c\u4e3a\u7684\u8fc7\u7a0b\u3002\u672c\u6587\u5c06\u4ecb\u7ecdPython\u4ee3\u7801\u91cd\u6784\u6280\u5de7\u548c\u574f\u5473\u9053\u8bc6\u522b\u3002<\/p>\n
"""\nPython\u4ee3\u7801\u91cd\u6784\u6280\u5de7\u4e0e\u574f\u5473\u9053\u8bc6\u522b\n\u5305\u542b\u63d0\u53d6\u65b9\u6cd5\u3001\u5185\u8054\u3001\u79fb\u52a8\u65b9\u6cd5\u7b49\u91cd\u6784\u6280\u5de7\n"""\n\nfrom typing import List, Dict, Optional, Tuple\nfrom dataclasses import dataclass\nfrom enum import Enum\n\n\n# ============ \u574f\u5473\u9053\u793a\u4f8b ============\nclass OrderProcessorBad:\n """\u574f\u5473\u9053\u793a\u4f8b\uff1a\u8fc7\u5927\u7684\u7c7b"""\n \n def __init__(self):\n self.orders = []\n self.customers = []\n self.products = []\n self.inventory = {}\n self.shipping_rates = {}\n \n def process_order(self, order_id: int, customer_id: int, \n product_ids: List[int], quantities: List[int],\n shipping_address: str, payment_method: str,\n discount_code: Optional[str] = None,\n gift_wrap: bool = False,\n special_instructions: str = ""):\n """\u574f\u5473\u9053\uff1a\u8fc7\u957f\u53c2\u6570\u5217\u8868"""\n # \u9a8c\u8bc1\u5ba2\u6237\n customer = None\n for c in self.customers:\n if c['id'] == customer_id:\n customer = c\n break\n \n if not customer:\n raise ValueError("\u5ba2\u6237\u4e0d\u5b58\u5728")\n \n # \u9a8c\u8bc1\u4ea7\u54c1\n products = []\n for pid in product_ids:\n for p in self.products:\n if p['id'] == pid:\n products.append(p)\n break\n \n # \u8ba1\u7b97\u4ef7\u683c\n total = 0\n for i, product in enumerate(products):\n qty = quantities[i]\n price = product['price']\n \n # \u5e94\u7528\u6298\u6263\n if discount_code:\n if discount_code == "SAVE10":\n price = price * 0.9\n elif discount_code == "SAVE20":\n price = price * 0.8\n \n total += price * qty\n \n # \u8ba1\u7b97\u8fd0\u8d39\n if total < 50:\n shipping = 5.99\n elif total < 100:\n shipping = 2.99\n else:\n shipping = 0\n \n total += shipping\n \n # \u5904\u7406\u652f\u4ed8\n if payment_method == "credit_card":\n print(f"\u5904\u7406\u4fe1\u7528\u5361\u652f\u4ed8: {total}")\n elif payment_method == "paypal":\n print(f"\u5904\u7406PayPal\u652f\u4ed8: {total}")\n elif payment_method == "bank_transfer":\n print(f"\u5904\u7406\u94f6\u884c\u8f6c\u8d26: {total}")\n \n # \u521b\u5efa\u8ba2\u5355\n order = {\n 'id': order_id,\n 'customer': customer,\n 'products': products,\n 'total': total,\n 'shipping_address': shipping_address\n }\n \n self.orders.append(order)\n return order\n\n\n# ============ \u91cd\u6784\u540e\u4ee3\u7801 ============\n@dataclass\nclass Customer:\n """\u5ba2\u6237"""\n id: int\n name: str\n email: str\n\n\n@dataclass\nclass Product:\n """\u4ea7\u54c1"""\n id: int\n name: str\n price: float\n\n\n@dataclass\nclass OrderItem:\n """\u8ba2\u5355\u9879"""\n product: Product\n quantity: int\n \n @property\n def subtotal(self) -> float:\n return self.product.price * self.quantity\n\n\nclass DiscountStrategy:\n """\u6298\u6263\u7b56\u7565"""\n \n DISCOUNTS = {\n "SAVE10": 0.9,\n "SAVE20": 0.8,\n "SAVE50": 0.5\n }\n \n @classmethod\n def apply_discount(cls, price: float, code: Optional[str]) -> float:\n if code and code in cls.DISCOUNTS:\n return price * cls.DISCOUNTS[code]\n return price\n\n\nclass ShippingCalculator:\n """\u8fd0\u8d39\u8ba1\u7b97\u5668"""\n \n @staticmethod\n def calculate_shipping(order_total: float) -> float:\n if order_total < 50:\n return 5.99\n elif order_total < 100:\n return 2.99\n return 0\n\n\nclass PaymentProcessor:\n """\u652f\u4ed8\u5904\u7406\u5668"""\n \n def process_payment(self, amount: float, method: str) -> bool:\n processors = {\n "credit_card": self._process_credit_card,\n "paypal": self._process_paypal,\n "bank_transfer": self._process_bank_transfer\n }\n \n processor = processors.get(method)\n if processor:\n return processor(amount)\n raise ValueError(f"\u4e0d\u652f\u6301\u7684\u652f\u4ed8\u65b9\u5f0f: {method}")\n \n def _process_credit_card(self, amount: float) -> bool:\n print(f"\u5904\u7406\u4fe1\u7528\u5361\u652f\u4ed8: {amount}")\n return True\n \n def _process_paypal(self, amount: float) -> bool:\n print(f"\u5904\u7406PayPal\u652f\u4ed8: {amount}")\n return True\n \n def _process_bank_transfer(self, amount: float) -> bool:\n print(f"\u5904\u7406\u94f6\u884c\u8f6c\u8d26: {amount}")\n return True\n\n\nclass CustomerRepository:\n """\u5ba2\u6237\u4ed3\u50a8"""\n \n def __init__(self):\n self._customers: Dict[int, Customer] = {}\n \n def add(self, customer: Customer):\n self._customers[customer.id] = customer\n \n def get_by_id(self, customer_id: int) -> Optional[Customer]:\n return self._customers.get(customer_id)\n\n\nclass ProductRepository:\n """\u4ea7\u54c1\u4ed3\u50a8"""\n \n def __init__(self):\n self._products: Dict[int, Product] = {}\n \n def add(self, product: Product):\n self._products[product.id] = product\n \n def get_by_ids(self, product_ids: List[int]) -> List[Product]:\n return [self._products[pid] for pid in product_ids if pid in self._products]\n\n\n@dataclass\nclass Order:\n """\u8ba2\u5355"""\n id: int\n customer: Customer\n items: List[OrderItem]\n shipping_address: str\n payment_method: str\n discount_code: Optional[str] = None\n \n @property\n def subtotal(self) -> float:\n return sum(item.subtotal for item in self.items)\n \n @property\n def shipping_cost(self) -> float:\n return ShippingCalculator.calculate_shipping(self.subtotal)\n \n @property\n def total(self) -> float:\n discounted = sum(\n DiscountStrategy.apply_discount(item.subtotal, self.discount_code)\n for item in self.items\n )\n return discounted + self.shipping_cost\n\n\nclass OrderService:\n """\u8ba2\u5355\u670d\u52a1\uff08\u91cd\u6784\u540e\uff09"""\n \n def __init__(self):\n self.customer_repo = CustomerRepository()\n self.product_repo = ProductRepository()\n self.payment_processor = PaymentProcessor()\n self.orders: List[Order] = []\n \n def create_order(\n self,\n customer_id: int,\n items_data: List[Tuple[int, int]], # (product_id, quantity)\n shipping_address: str,\n payment_method: str,\n discount_code: Optional[str] = None\n ) -> Order:\n """\u521b\u5efa\u8ba2\u5355"""\n # \u83b7\u53d6\u5ba2\u6237\n customer = self.customer_repo.get_by_id(customer_id)\n if not customer:\n raise ValueError("\u5ba2\u6237\u4e0d\u5b58\u5728")\n \n # \u83b7\u53d6\u4ea7\u54c1\u5e76\u521b\u5efa\u8ba2\u5355\u9879\n product_ids = [item[0] for item in items_data]\n products = self.product_repo.get_by_ids(product_ids)\n \n if len(products) != len(product_ids):\n raise ValueError("\u90e8\u5206\u4ea7\u54c1\u4e0d\u5b58\u5728")\n \n order_items = [\n OrderItem(product, qty)\n for product, (_, qty) in zip(products, items_data)\n ]\n \n # \u521b\u5efa\u8ba2\u5355\n order = Order(\n id=len(self.orders) + 1,\n customer=customer,\n items=order_items,\n shipping_address=shipping_address,\n payment_method=payment_method,\n discount_code=discount_code\n )\n \n # \u5904\u7406\u652f\u4ed8\n self.payment_processor.process_payment(order.total, payment_method)\n \n self.orders.append(order)\n return order\n\n\ndef demonstrate_refactoring():\n """\u6f14\u793a\u91cd\u6784"""\n print("="*60)\n print("\u4ee3\u7801\u91cd\u6784\u6f14\u793a")\n print("="*60)\n \n # \u8bbe\u7f6e\u6570\u636e\n service = OrderService()\n \n # \u6dfb\u52a0\u5ba2\u6237\n service.customer_repo.add(Customer(1, "Alice", "alice@example.com"))\n \n # \u6dfb\u52a0\u4ea7\u54c1\n service.product_repo.add(Product(1, "Laptop", 999.99))\n service.product_repo.add(Product(2, "Mouse", 29.99))\n \n # \u521b\u5efa\u8ba2\u5355\n order = service.create_order(\n customer_id=1,\n items_data=[(1, 1), (2, 2)],\n shipping_address="123 Main St",\n payment_method="credit_card",\n discount_code="SAVE10"\n )\n \n print(f"\/n\u8ba2\u5355ID: {order.id}")\n print(f"\u5ba2\u6237: {order.customer.name}")\n print(f"\u5546\u54c1\u5c0f\u8ba1: ${order.subtotal:.2f}")\n print(f"\u8fd0\u8d39: ${order.shipping_cost:.2f}")\n print(f"\u603b\u8ba1: ${order.total:.2f}")\n \n print("\/n" + "="*60)\n print("\u91cd\u6784\u6539\u8fdb")\n print("="*60)\n print("1. \u63d0\u53d6\u7c7b: Customer, Product, OrderItem")\n print("2. \u63d0\u53d6\u65b9\u6cd5: ShippingCalculator, PaymentProcessor")\n print("3. \u5f15\u5165\u7b56\u7565\u6a21\u5f0f: DiscountStrategy")\n print("4. \u4f7f\u7528\u4ed3\u50a8\u6a21\u5f0f: CustomerRepository, ProductRepository")\n print("5. \u51cf\u5c11\u53c2\u6570: \u4f7f\u7528\u5bf9\u8c61\u5c01\u88c5\u53c2\u6570")\n print("="*60)\n\n\ndef main():\n """\u4e3b\u51fd\u6570"""\n demonstrate_refactoring()\n\n\nif __name__ == "__main__":\n main()<\/code><\/pre>\n\u91cd\u6784\u67b6\u6784\u56fe<\/h3>\n