工厂模式

示例：

/* Product */
interface Animal {
    void makeSound();
}

/* Concrete Product */
class Cat implements Animal {
    @Override
    public void makeSound() {
        System.out.println("Cat: Meow Meow");
    }
}

/* Concrete Product */
class Dog implements Animal {
    @Override
    public void makeSound() {
        System.out.println("Dog: woof woof woof");
    }
}

/* Creator */
interface Creator {
    Animal CreateAnimal();
}

/* Concrete Creator */
class CatCreator implements Creator{
    @Override
    public Animal CreateAnimal() {
        return  new Cat();
    }
}

/* Concrete Creator */
class DogCreator implements Creator{
    @Override
    public Animal CreateAnimal() {
        return  new Dog();
    }
}

测试代码：

public class Task {
    public static void main(String args[]){
        Creator factory = new CatCreator();
        Animal cat = factory.CreateAnimal();
        cat.makeSound();

        Creator factoryDog = new DogCreator();
        Animal dog = factoryDog.CreateAnimal();
        dog.makeSound();
    }
}