http://www.oschina.net/question/100267_61129?sort=default&p=1#tags_nav
http://www.cnblogs.com/top5/archive/2011/12/29/2306241.html
http://www.open-open.com/lib/view/open1342353575260.html
http://blog.csdn.net/ithomer/article/details/7896313