http://www.cnblogs.com/submarine/archive/2011/08/03/2126423.html http://blog.youkuaiyun.com/xiaohuan1991/article/details/6956629
http://www.cnblogs.com/submarine/archive/2011/08/03/2126423.html http://blog.youkuaiyun.com/xiaohuan1991/article/details/6956629