说明：  对象与接口 COM应用模型及COM库 类厂对象 VC++调用COM组件的方法 使用MFC开发COM组件 使用ATL开发COM组件 扩展:com组件和一般dll的区别
(Objects and interfaces COM Application Model and COM Library Category Factory Object The Method of Calling COM Component by VC++ Using MFC to Develop COM Components Using ATL to Develop COM Components Extension: the difference between COM components and general DLLs)