http://www.cnblogs.com/angeldevil/p/3296381.html
http://blog.csdn.net/luoshengyang/article/details/6618363
http://www.linuxidc.com/Linux/2012-07/66195.htm
http://www.cnblogs.com/bastard/archive/2012/10/17/2728155.html
http://www.cnblogs.com/albert1017/p/3849585.html
原文：http://www.cnblogs.com/chuiyuan/p/4808919.html