工厂方法模式

在简单工厂模式中，也就是上一篇博文中写了一个全知全能的园丁角色(FruitGardener),控制所有的作物的种植，生长和收获，

但是，如果这个农场变得更大了，那么管理也要更加专业化，过去的全能人物也就没有了，每一种农作物都有专门的园丁管理，

形成规模化和专业化生产。

因此，在农场系统中就要重新设计，要有每一种作物对应的园丁，因此设计图如下：

抽象工厂类FruitGardener是工厂方法模式的核心，但它并不掌握水果类或蔬菜类的生杀大权，相反这项权力被交给子类，即

AppleGardener,StrawberryGardener,GrapeGardener来完成。

产品角色的等级结构为：

源码为：

Fruit：

package FactoryMethodModel;public interface Fruit {void grow();void harvest();void plant();}

Apple:

package FactoryMethodModel;public class Apple implements Fruit {private int treeAge;@Overridepublic void grow() {System.err.println("Apple is growing.....");}@Overridepublic void harvest() {System.err.println("Apple has been harvested.");}@Overridepublic void plant() {System.err.println("Apple has been planted.");}public int getTreeAge() {return treeAge;}public void setTreeAge(int treeAge) {this.treeAge = treeAge;}}

Strawberry:

package FactoryMethodModel;public class Strawberry implements Fruit {@Overridepublic void grow() {System.err.println("Strawberry is growing.....");}@Overridepublic void harvest() {System.err.println("Strawberry has been harvested.");}@Overridepublic void plant() {System.err.println("Strawberry has been planted.");}}

Grape:

package FactoryMethodModel;public class Grape implements Fruit {private boolean seedless;@Overridepublic void grow() {System.err.println("Grape is growing....");}@Overridepublic void harvest() {System.err.println("Grape has been harvested.");}@Overridepublic void plant() {System.err.println("Grape has been planted.");}public boolean isSeedless() {return seedless;}public void setSeedless(boolean seedless) {this.seedless = seedless;}}

工厂角色的等级结构为：

FruitGardener:

package FactoryMethodModel;public interface FruitGardener {/** * 工厂方法 */public Fruit factory();}

AppleGardener:

package FactoryMethodModel;public class AppleGardener implements FruitGardener {@Overridepublic Fruit factory() {return new Apple();}}

StrawberryGardener:

package FactoryMethodModel;public class StrawberryGardener implements FruitGardener {@Overridepublic Fruit factory() {return new Strawberry();}}

GrapeGardener:

package FactoryMethodModel;public class GrapeGardener implements FruitGardener {@Overridepublic Fruit factory() {return new Grape();}}

如此，便是实现了工厂方法模式。