http://noside.iteye.com/blog/1145325
http://www.cnblogs.com/eafy/archive/2007/10/10/919361.html
http://apluck.iteye.com/blog/1197645
http://hi.baidu.com/caijian5219999/blog/item/437f7ed2f8b2ef2b9a50272f.html