参考:http://www.jianshu.com/p/a172a1b69fdd
http://www.jianshu.com/p/1ae0ef652f63
http://www.jb51.net/article/76110.htm
http://www.tangshuang.net/2359.html
http://wyong.blog.51cto.com/1115465/1692322
常见问题http://kf.qq.com/faq/140225MveaUz150413VNj6nm.html