http://www.cnblogs.com/xing901022/p/4309840.html
http://www.cnblogs.com/CareySon/archive/2012/04/27/HTTP-Protocol.html
http://www.cnblogs.com/simple-blog/p/4377647.html
http://www.cnblogs.com/mengwang024/p/4448395.html
原文：http://www.cnblogs.com/chuiyuan/p/4466513.html