Factory Method模式

Product.java

定义产品的一个模板,每一个继承Product的类都要实现自己的use方法.

public abstract class Product {
    public abstract void use();
}

　　

Factory.java

为子类(不同种的工厂)定义一个通用模板方法create(),子类可以个性化地实现createProduct()和registerProduct().

public abstract class Factory {
    public final Product create(String owner) {
        Product p = createProduct(owner);
        registerProduct(p);
        return p;
    }

    protected abstract Product createProduct(String owner);

    protected abstract void registerProduct(Product product);
}

　　

IDCard.java

Product的子类

public class IDCard extends Product {
    private String owner;

    IDCard(String owner) {
        System.out.println("制作" + owner + "的ID卡.");
        this.owner = owner;
    }

    @Override
    public void use() {
        System.out.println("使用" + owner + "的ID卡");
    }

    public String getOwner() {
        return owner;
    }
}

　　

IDCardFactory.java

public class IDCardFactory extends Factory {
    private List owners = new ArrayList();

    @Override
    protected Product createProduct(String owner) {
        return new IDCard(owner);
    }

    @Override
    protected void registerProduct(Product product) {
        owners.add(((IDCard) product).getOwner());
    }

    public List getOwners() {
        return owners;
    }
}

Main.java

测试类

public class Main {
    public static void main(String[] args) {
        Factory factory = new IDCardFactory();
        Product card1 = factory.create("kristin");
        Product card2 = factory.create("John");
        Product card3 = factory.create("Marry");
        card1.use();
        card2.use();
        card3.use();
    }
}

运行结果: