资料：
https://www.cnblogs.com/dkblog/archive/2011/03/02/1980644.html
http://www.cnblogs.com/stubborn412/p/3818423.html
http://blog.csdn.net/chixujohnny/article/details/51782826
http://www.cnblogs.com/sislcb/archive/2008/11/26/1341455.html
https://www.cnblogs.com/jxzheng/p/5186490.html
