dd

http://www.cnblogs.com/witcxc/archive/2011/12/28/2304870.html

http://www.cnblogs.com/holbrook/archive/2012/02/15/2357335.html

http://blog.csdn.net/seagle0128/article/details/4530871

http://www.cnblogs.com/karotte/archive/2012/06/06/2537670.html

http://www.cnblogs.com/jerry-chou/archive/2011/02/22/1960011.html

http://blog.csdn.net/luckyan315/article/details/7318127