http://houjixin.blog.163.com/blog/static/35628410201411275719843/
http://blog.csdn.net/lastsweetop/article/details/8881909
http://blog.csdn.net/gtuu0123/article/details/5811143
http://blog.163.com/bobile45@126/blog/static/9606199220139303343415/
原文：http://www.cnblogs.com/diyunpeng/p/4316815.html