http://www.cnblogs.com/Gaojiecai/archive/2011/12/10/2283156.html
http://www.2cto.com/kf/201205/131876.html
http://blog.csdn.net/woaieillen/article/details/7378324
http://www.cnblogs.com/gzggyy/archive/2012/10/30/2746521.html
http://my.oschina.net/u/1036767/blog/266317
原文：http://www.cnblogs.com/liyiran/p/4672657.html