java - 工厂方法与抽象工厂

Question

这个问题已经有答案了:

What are the differences between Abstract Factory and Factory design patterns? (21 个回答)

已关闭 9 年前。

我读过工厂方法，其中子类创建所需的对象，而抽象工厂具有具体类创建所需对象的方法

工厂方法

public class PizzaStore {

    public Pizza orderPizza(String type) {
        Pizza pizza = createPizza(type);
        pizza.prepare();
        pizza.bake();
        pizza.cut();
    }

    abstract Pizza createPizza(String type);

}

public NewYorkPizzaStore extends PizzaStore {

    public Pizza createPizza(String type) {
        Pizza pizza = null;
        if("cheese".equals(type)) {
            pizza = new CheesePizza();
        }
        else if("onion".equals(type)) {
            pizza = new OnionPizza();
        }

        return pizza;
    }

}

public class pizzaTestDriveByFactoryMethod() {

    public static void main(String args[]) {
        PizzaStore ps =  new NewYorkPizzaStore();
        ps.orderPizza("cheese");
    }

}

使用工厂

public class NewYorkPizzaFactory extends PizzaFactory {

    public Pizza createPizza(String pizza) {
        Pizza pizza = null;
        if("cheese".equals(type)) {
            pizza = new CheesePizza();
        } else if("onion".equals(type)) {
            pizza = new OnionPizza();
        }

        return pizza;
    }

}

public class PizzaStore {

    PizzaFactory factory;

    public PizzaStore(PizzaFactory factory) {
        this.factory =  factory
    }

    public Pizza orderPizza(String type) {
        Pizza pizza =  factory.createPizza(type)
        pizza.prepare();
        pizza.bake();
        pizza.cut();
        return pizza;
    }

}

public class pizzaTestDriveByAbstractFactory() {

    public static void main(String args[]) {
        PizzaFactory nwFactory = new NewYorkPizzaFactory();
        PizzaStore ps =  new PizzaStore(nwFactory);
        ps.orderPizza("cheese");
    }

}

使用工厂方法和抽象工厂实现相同的用例。为什么应该有FactoryMethod而不是使用Abstract Factory或Utility Factory(例如Chicago Factory/NewYorkFactory)。工厂方法在什么情况下对抽象方法有用？

Answer 1

主要区别在于，您可以实现工厂对象，而无需对正在处理工厂的对象进行子类化。这也意味着您可以进行诸如即时交换工厂之类的事情。另一方面，如果您只是做一些简单或紧密耦合的事情，那么您不妨只提供更简单的方法。