http://www.cnblogs.com/lancidie/archive/2011/01/31/1948430.html
http://www.cnblogs.com/ly4cn/archive/2006/04/12/373494.html
http://blog.csdn.net/woyaowenzi/article/details/4581655
用托管C++包装现有的DLL，供C#调用
