四、Factory Method 工厂方法模式

需求：对象的创建由工厂统一创建，会使用到模板模式

代码清单：

工厂：

public abstract class Factory {
    public abstract  Product createProduct(String owner);
    public abstract  void registerProduct(Product product);

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

产品：

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

子工厂：

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

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

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

    public List getOwners(){
        return owners;
    }
}

子产品：

public class IDCard extends Product{
    private String owner;

    IDCard(String owner){
        this.owner = owner;
    }

    @Override
    public void use() {
        System.out.println("使用"+owner+"的身份证");
    }

    public String getOwner(){
        return owner;
    }
}

测试方法：

public class Main {
    public static void main(String[] args){
        Factory factory = new IDCardFactory();
        Product p1 = factory.create("1");
        Product p2 = factory.create("2");
        Product p3 = factory.create("3");
        p1.use();
        p2.use();
        p3.use();
    }
}