http://blog.csdn.net/jyy_12/article/details/46416161
http://blog.csdn.net/jyy_12/article/details/46593251
http://blog.csdn.net/jyy_12/article/details/46593313
http://blog.csdn.net/jyy_12/article/details/46593337
原文：http://www.cnblogs.com/vito13/p/5116618.html