不解释:
http://blog.csdn.net/sfdev/article/details/9172801
http://blog.csdn.net/qinjuning/article/details/7110211
http://hunankeda110.iteye.com/blog/1944311
http://blog.csdn.net/guolin_blog/article/details/9153747
原文：http://blog.csdn.net/lixiaopeng23/article/details/20547013