heroxiao的专栏

                                        Factory Method Pattern         This factory method pattern usually is used to create difference objects according to subclasses which inherit the same inter

All these implementations have a prvate and parameterless constructor.First Version -- not thread safe Class sealed Singleton {     private static  Singleton instance = null;     private Singleton(){

CDM 概念模型 PDM 物理模型 OOM 面向对象模型