java design pattern - factory pattern

最近看的java design pattern 都出自 Java design patterns 一书。
这个factory pattern 要取决于用户的输入来实例化不同的类。 而super class 可以是个interface ,也可以是个普通的类。

Usage in JDK:  值得一看
java.util.Calendar, ResourceBundle, and NumberFormat geninstance() methods use Factory pattern.
valueof() method in wrapper classes like Boolean, Integer etc. 

下面是例子：

package factorypattern;


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");
    }

}

public class FactoryPatternDemo {
    static IMobile createMobile(String type){
        IMobile mob=null;
        if("len".equalsIgnoreCase(type)){
            mob = new Lenovo();
            System.out.println("Lenovo created");
        }else if ("sam".equalsIgnoreCase(type)){
            mob = new Samsung();
            System.out.println("Samsung created");
        }
        return mob;
    }

    public static void main(String[] args){
        Lenovo len = (Lenovo) createMobile("len");
        len.batterPower();
        System.out.println(len);

        Samsung sam = (Samsung) createMobile("sam");
        sam.cost();
        System.out.println(sam);
    }
}