创建型-抽象工厂
角色
- 抽象工厂: 声明创建一个族产品对象的方法,每个方法对应一中产品,抽象工厂可以是接口,也可以是抽象类;
- 具体工厂: 实现抽象工厂接口,复杂创建具体的一族产品;
- 抽象产品:定义一类产品的公共接口,描述一类产品的特定行为或者属性;
- 具体产品:实现抽象产品接口,定义具体产品的特定行为和属性;
其中,一族的概念可根据业务情况进行分族。比如:形状,颜色可分为两个族,再比如,植物, 动物也可以分为两个族。族的概念根据区分维度不同可分为不同的族;
图解
实现案例
这个案例中按照年龄将人分为小孩,老年人,中年人三族,产品分为上衣、裤子、鞋子三个种类;其中实现了老年人和小孩两个族衣服的抽象工厂。
抽象产品类:
/** 上衣抽象类*/
public abstract class Jacket {public abstract void wearJacket();
}/** 鞋子抽象类*/
public abstract class Shoes {public abstract void wearShoes();
}/** 裤子抽象类*/
public abstract class Trousers {public abstract void wearTrousers();
}
具体产品类:
/** 小孩衣服的具体类*/public class ChildishJacket extends Jacket {@Overridepublic void wearJacket() {System.out.println("小孩的上衣");}
}
public class ChildishShoes extends Shoes {@Overridepublic void wearShoes() {System.out.println("小孩的鞋子");}
}
public class ChildishTrousers extends Trousers {@Overridepublic void wearTrousers() {System.out.println("小孩的裤子");}
}/** 老年人衣服的具体类*/
public class OldJacket extends Jacket {@Overridepublic void wearJacket() {System.out.println("老年人上衣");}
}
public class OldTrousers extends Trousers {@Overridepublic void wearTrousers() {System.out.println("老年人的裤子");}
}
public class OldShoes extends Shoes {@Overridepublic void wearShoes() {System.out.println("老年人的鞋子");}
}
抽象工厂类:
/** 生产衣服的抽象工厂*/
public abstract class AbstractClothesFactory {public abstract Jacket createJacket();public abstract Shoes createShoes();public abstract Trousers createTrousers();
}
具体工厂类:
/** 儿童衣服生产工厂*/
public class ChildishClothesFactory extends AbstractClothesFactory {private static ChildishClothesFactory INSTANCE = new ChildishClothesFactory();public static ChildishClothesFactory getInstance(){return INSTANCE;}@Overridepublic Jacket createJacket() {return new ChildishJacket();}@Overridepublic Shoes createShoes() {return new ChildishShoes();}@Overridepublic Trousers createTrousers() {return new ChildishTrousers();}
}/** 老年人衣服生产工厂*/
public class OldClothesFactory extends AbstractClothesFactory{private static OldClothesFactory INSTANCE = new OldClothesFactory();public static OldClothesFactory getInstance(){return INSTANCE;}@Overridepublic Jacket createJacket() {return new OldJacket();}@Overridepublic Shoes createShoes() {return new OldShoes();}@Overridepublic Trousers createTrousers() {return new OldTrousers();}
}
使用:
public class Main {public static void main(String[] args) {//生产儿童一族的衣服ChildishClothesFactory childishClothesFactory = ChildishClothesFactory.getInstance();Jacket childishJacket = childishClothesFactory.createJacket();Shoes childishShoes = childishClothesFactory.createShoes();Trousers childishTrousers = childishClothesFactory.createTrousers();//生产老年人一族的衣服OldClothesFactory oldClothesFactory = OldClothesFactory.getInstance();Jacket oldJacket = oldClothesFactory.createJacket();Shoes oldShoes = oldClothesFactory.createShoes();Trousers oldTrousers = oldClothesFactory.createTrousers();childishJacket.wearJacket();oldJacket.wearJacket();}
}
总结
- 抽象工厂是生产一族的产品,族的概念可根据不同的业务规则区分。
- 扩展产品族非常困难。增加一个新的产品族需要修改抽象工厂和所有具体工厂的代码。
- 对于新增族来说,满足开闭原则,而对于新增产品来说,不满足开闭原则。