Abstract Factory Pattern

Thread.start() Membro desde: 19/08/2011 23:07:11 Mensagens: 35 Offline

Na boa,

Olha só esse primeiro código extraído da Wikipedia:

/* GUIFactory example -- */
 
interface GUIFactory {
    public Button createButton();
}
 
class WinFactory implements GUIFactory {
    public Button createButton() {
        return new WinButton();
    }
}
class OSXFactory implements GUIFactory {
    public Button createButton() {
        return new OSXButton();
    }
}
 
 
interface Button {
    public void paint();
}
 
class WinButton implements Button {
    public void paint() {
        System.out.println("I'm a WinButton");
    }
}
class OSXButton implements Button {
    public void paint() {
        System.out.println("I'm an OSXButton");
    }
}
 
 
class Application {
    public Application(GUIFactory factory) {
        Button button = factory.createButton();
        button.paint();
    }
}
 
public class ApplicationRunner {
    public static void main(String[] args) {
        new Application(createOsSpecificFactory());
    }
 
    public static GUIFactory createOsSpecificFactory() {
        int sys = readFromConfigFile("OS_TYPE");
        if (sys == 0) {
            return new WinFactory();
        } else {
            return new OSXFactory();
        }
    }
}

Porque gerar FÁBRICAS diferentes para gerar botões diferentes ??

Por que não fazer apenas uma fábrica como no meu código abaixo e então instanciar botões diferentes ??

package abstractfactory;

/* GUIFactory example -- */

interface GUIFactory {
    public Button createButton();
}
 
class WinFactory implements GUIFactory {
    public Button createButton() {
        return new WinButton();
    }
}
class OSXFactory implements GUIFactory {
    public Button createButton() {
        return new OSXButton();
    }
}
 
class MinhaFactory {
	public static Button createButton(int tipo) {
		if ( tipo == 0 ) 
		  return new WinButton();
		else if (tipo == 1)
			return new OSXButton();
		return null;
	}
}
 
interface Button {
    public void paint();
}
 
class WinButton implements Button {
    public void paint() {
        System.out.println("I'm a WinButton");
    }
}
class OSXButton implements Button {
    public void paint() {
        System.out.println("I'm an OSXButton");
    }
}

class Application {
    public Application(GUIFactory factory) {
        Button button = factory.createButton();
        button.paint();
    }
}
 
public class AbstractFactory {
    public static void main(String[] args) {        
        Button botao = MinhaFactory.createButton(0); // ou 1
        System.out.println(botao.getClass());
        botao.paint();
        
    }
 
}

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