http://blog.csdn.net/guolin_blog/article/details/17482095/
http://blog.csdn.net/guolin_blog/article/details/17482165
http://blog.csdn.net/guolin_blog/article/details/17612763
http://blog.csdn.net/guolin_blog/article/details/17656437
原文：http://www.cnblogs.com/sytfyf/p/6249616.html