创建型模式--抽象工厂模式(Abstract Factory)

Abstract Factory:Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

抽象工厂(Abstract Factory)模式是所有工厂模式中最抽象和最具有一般性的形态，和工厂方法模式的最大区别在于，工厂方法模式针对的是一个产品等级结构，而抽象工厂模式则需要对多个产品等级结构。

一：引入

最早起源应用于不通操作系统的视窗构件，如一个Button类在windows环境和unix环境下有对应的实现，如果使用工厂方法模式，需要每个Concrete Product类对应一个Concrete Factory，在太多构件的情况下显然不合适。

改为有两个Concrete Factory(因为有两大类(当然也可以有多个类)),每个Factory类负责创建这一类的所有对象。




public class WinFactory implements AbstractFactory...{


public Button createButton()




...{


return new WinButton();


}


public Text createText()




...{


return new WinText();


}


}






public class UnixFactory implements AbstractFactory...{


public Button createButton()




...{


return new UnixButton();


}


public Text createText()




...{


return new UnixText();


}


}

二：结构



三：实际应用

最早起源应用于不通操作系统的视窗构件。

四：适用情形

Use the Abstract Factory pattern when

a system should be independent of how its products are created, composed, and represented.

a system should be configured with one of multiple families of products.

a family of related product objects is designed to be used together, and you need to enforce this constraint.

you want to provide a class library of products, and you want to reveal just their interfaces, not their implementations.

参考文献：
1:阎宏，《Java与模式》，电子工业出版社
2:Eric Freeman & Elisabeth Freeman，《Head First Design Pattern》，O'REILLY