http://www.genshuixue.com/i-cxy/p/15285416

http://blog.csdn.net/hw_libo/article/details/39080809

http://hedengcheng.com/?p=771

https://yq.aliyun.com/articles/50926

http://blog.csdn.net/ifollowrivers/article/details/73614549

http://www.uml.org.cn/sjjm/201205302.asp