Java 设计模式-抽象工厂模式

需求分析:
在工厂方法中我们定义了一个比萨店来规范比萨的制作. 现在为了进一步规范, 我们希望确保加盟店都能够使用高质量的原料, 所以我们需要构建一个原料工厂. 由于比萨的制作需要多种原料, 我们希望能够调用原料工厂的不同方法来获取不同的原料.

public interface PizzaIngredientFactory {
    // 获取面团
    public Dough createDough();
    // 获取酱
    public Sauce createSauce();
    // 获取奶酪
    public Cheese createCheese();
    // 获取蔬菜
    public Veggies[] createVeggies();
    // 获取意大利肠
    public Pepperoni createPepperoni();
    // 获取蛤蜊
    public Clam createClam();
}

public class NYPizzaIngredientFactory implements PizzaIngredientFactory {
    public Dough createDough() {
        return new ThinCrustDough();
    }
    
    public Sauce createSauce() {
        return new MarinaraSauce();
    }
    
    public Cheese createCheese() {
        return new ReggianoCheese();
    }
    
    public Veggies[] createVeggies() {
        Veggies veggies = new {new Garlic(), new Onion(), new Mushroom(), new RedPepper()};
        return veggies;
    }
    
    public Clam createClam() {
        return new FreshClam();
    }
}

public abstract class Pizza {
    private String name;
    private Dough dough;
    private Sauce sauce;
    private Veggies veggies[];
    private Cheese cheese;
    private Pepperoni pepperoni;
    private Clam clam;
    
    protected void prepare();
    
    public void bake() {
        System.out.println("Bake for 25 minutes at 350");
    }
    
    public void cut() {
        System.out.println("Cutting the pizza into diagonal slices");
    }
    
    public void box() {
        System.out.println("Place pizza in official PizzaStore box");
    }
    
    public void setName(String name) {
        this.name = name;
    }
    
    public String getName() {
        return this.name;
    }
}

public class CheesePizza extends Pizza {
    private PizzaIngredientFactory ingredientFactory;
    
    public CheesePizza(PizzaIngredientFacotry ingredientFactory) {
        this.ingredientFactory = ingredientFactory;
    }
    
    @Override
    public void prepare() {
        // 这里调用原料工厂
        dough = ingredientFactory.createDough();
        sauce = ingredientFactory.createSauce();
        cheese = ingredientFactory.createCheese();
    }
}

抽象工厂定义:
Provide an interface for creating families of related or dependent objects without specifying their concrete classes(为创建一组相关或相互依赖的对象提供一个接口, 而且无需指定它们的具体类).

抽象工厂的应用:
javax.xml.parsers.DocumentBuilderFactory#newInstance() 方法
javax.xml.transform.TransformerFactory#newInstance() 方法 javax.xml.xpath.XPathFactory#newInstance() 方法

参考:
[1] : Java 库中的设计模式
[2] : 设计模式之禅
[3] : Head First 设计模式
[4] : 三种工厂方法模式