简单工厂模式，工厂工厂模式，抽象工厂模式的示例代码实现

以下是三种工厂模式的示例代码实现：

1. 简单工厂模式：

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return "Woof!"

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

class AnimalFactory:
    def create_animal(self, name, animal_type):
        if animal_type == "dog":
            return Dog(name)
        elif animal_type == "cat":
            return Cat(name)
        else:
            return None

factory = AnimalFactory()
dog = factory.create_animal("Buddy", "dog")
cat = factory.create_animal("Misty", "cat")

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

2. 工厂方法模式：

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return "Woof!"

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

class AnimalFactory:
    def create_animal(self, name):
        pass

class DogFactory(AnimalFactory):
    def create_animal(self, name):
        return Dog(name)

class CatFactory(AnimalFactory):
    def create_animal(self, name):
        return Cat(name)

dog_factory = DogFactory()
cat_factory = CatFactory()

dog = dog_factory.create_animal("Buddy")
cat = cat_factory.create_animal("Misty")

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

3. 抽象工厂模式：

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return "Woof!"

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

class AnimalFactory:
    def create_dog(self, name):
        pass

    def create_cat(self, name):
        pass

class DogFactory(AnimalFactory):
    def create_dog(self, name):
        return Dog(name)

class CatFactory(AnimalFactory):
    def create_cat(self, name):
        return Cat(name)

class PetStore:
    def __init__(self, animal_factory):
        self.animal_factory = animal_factory

    def buy_dog(self, name):
        return self.animal_factory.create_dog(name)

    def buy_cat(self, name):
        return self.animal_factory.create_cat(name)

dog_factory = DogFactory()
cat_factory = CatFactory()

pet_store = PetStore(dog_factory)
dog = pet_store.buy_dog("Buddy")
print(dog.speak())  # Output: Woof!

pet_store = PetStore(cat_factory)
cat = pet_store.buy_cat("Misty")
print(cat.speak())  # Output: Meow