http://www.cnblogs.com/liguanghui/archive/2011/11/09/2242309.html
http://www.cnblogs.com/dreamszx/archive/2012/09/29/2708558.html
http://www.cnblogs.com/liguanghui/archive/2011/11/09/2242309.html
http://www.cnblogs.com/dreamszx/archive/2012/09/29/2708558.html