java design pattern - abstract factory pattern

这个desgin pattern 的意思是factory of factories, 不同于factory pattern, 根据用户的input 来new 不同的对象，这里是直接new 不同的factory。然后让不同的工厂来负责生产不同的对象。
我觉得已经有让人找不到干活的代码到底在哪里的意思了。
Usage in JDK: 
javax.xml.parsers.DocumentBuilderFactory #newInstance()
javax.xml.transform.TransformerFactory #newInstance()
javax.xml.xpath.XPathFactory #newInstance()

package abstractfactory;

interface IMobile{
    public void cost();
    public void pictureCapacity();
    public void batterPower();
}

class Lenovo implements IMobile{

    @Override
    public void cost(){
        System.out.println("Lenovo Cost starts from 10000");
    }

    @Override
    public void pictureCapacity(){
        System.out.println("Lenovo camera capacity starts from 10MP");

    }

    @Override
    public void batterPower(){
        System.out.println("Lenovo battery power starts from 2500 MAH");
    }

    @Override
    public String toString(){
        return "Lenovo [toString()= " +super.toString() +" ]";
    }
}

class Samsung implements IMobile{

    @Override
    public void cost(){
        System.out.println("Samsung Cost starts from 6000");
    }

    @Override
    public void pictureCapacity(){
        System.out.println("Samsung camera capacity starts from 4MP");

    }

    @Override
    public void batterPower(){
        System.out.println("Samsung battery power starts from 1200 MAH");
    }

}

interface IMobileFactory{
    public IMobileFactory createMobile(String type);
}

class MobileFactory implements IMobileFactory{

    @Override
    public IMobileFactory createMobile(String type){
        IMobileFactory obj = null;
        if("lenf".equalsIgnoreCase(type)){
            obj = new LenovoMobileFactory();
        }else if("samf".equalsIgnoreCase(type)){
            obj = new SamsungMobileFactory();
        }
        return obj;
    }
}

class LenovoMobileFactory extends MobileFactory{
    Lenovo createLenovoMobile(){
        return new Lenovo();
    }
}

class SamsungMobileFactory extends MobileFactory{
    Samsung createMobileFactory(){
        return new Samsung();
    }
}

public class AbstractFactoryDemo {
    public static void main(String[] args){
        MobileFactory factory = new MobileFactory();
        LenovoMobileFactory lmf = (LenovoMobileFactory)factory.createMobile("lenf");
        Lenovo ln = (Lenovo)lmf.createLenovoMobile();
        ln.batterPower();
        ln.pictureCapacity();
    }
}