https://www.cnblogs.com/rwxwsblog/p/5667772.html
http://www.mamicode.com/info-detail-1651279.html
http://www.cnblogs.com/chenjiaxin–007/p/6807979.html
http://blog.csdn.net/xushuai110/article/details/50387319
http://www.showerlee.com/archives/1880