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();    }}