Python中的工厂模式

# 定义一个接口
class Animal:
    def speak(self):
        pass

# 定义具体的对象类
class Dog(Animal):
    def speak(self):
        return "Woof!"

class Cat(Animal):
    def speak(self):
        return "Meow!"

# 定义工厂类
class AnimalFactory:
    def create_animal(self, animal_type):
        if animal_type == "dog":
            return Dog()
        elif animal_type == "cat":
            return Cat()
        else:
            raise ValueError("Invalid animal type.")

# 使用工厂类创建对象
factory = AnimalFactory()
dog = factory.create_animal("dog")
cat = factory.create_animal("cat")

print(dog.speak())  # 输出: Woof!
print(cat.speak())  # 输出: Meow!