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
