QPointer更安全，QScopedPointer自动出范围就删除，QSharedDataPointer帮助实现隐式共享
http://blog.csdn.net/hai200501019/article/details/8474582
http://blog.csdn.net/hai200501019/article/details/8482876
http://blog.csdn.net/hai200501019/article/details/8502451
http://blog.csdn.net/hai200501019/article/details/8474582
http://blog.csdn.net/hai200501019/article/details/8482876
http://blog.csdn.net/hai200501019/article/details/8502451
