Java设计模式（二）：工厂方法模式

我们已经知道了工厂模式的弊端，那么怎么解决呢？在工厂模式中，我们用一个工厂类就创建了多个对象，那么我们是否可以对每一种笔都创建工厂类呢?很明显是可以的。

创建父类Pen，让BellPen、BrushPen、Pencil继承Pen;同理，我们那可以创建父类PenFactory,并定义抽象方法来创建各工厂，让BellPenFactory、BrushPenFactory、PencilFactory继承PenFactory

Pen

pen.java

public abstract class Pen {
public abstract void write();
}

子类:BellPen

public class BellPen extends Pen {
@Override
public void write() {
        System.out.println("圆珠笔");
    }
}

BrushPen.java

public class BrushPen extends Pen {
@Override
public void write() {
        System.out.println("毛笔");
    }
}

Pencil.java

public class Pencil extends Pen {
@Override
public void write() {
        System.out.println("铅笔");
    }
}

PenFactory.java

父类PenFactory.java

public abstract class PenFactory {
public abstract Pen createPen();
}

BellPenFactory.java

public class BellPenFactory extends PenFactory {
@Override
public Pen createPen() {
return new BellPen();
    }
}

BrushPenFactory.java

public class BrushPenFactory extends PenFactory {

@Override
public Pen createPen() {

return new BrushPen();
    }

}

public class PencilFactory extends PenFactory {

@Override
public Pen createPen() {

return new Pencil();
    }
}

测试工厂类

public class FactoryTest {

public static void main(String[] args) {
         PenFactory factory ;

         factory = new BellPenFactory();
         BellPen bellPen = (BellPen) factory.createPen();
         bellPen.write();

         factory = new BrushPenFactory();
         BrushPen brushPen = (BrushPen) factory.createPen();
         brushPen.write();

         factory = new PencilFactory();
         Pencil pencil = (Pencil) factory.createPen();
         pencil.write();
    }
}