Http Header

https://stackoverflow.com/questions/35907642/custom-header-to-httpclient-request

https://stackoverflow.com/questions/12022965/adding-http-headers-to-httpclient

https://stackoverflow.com/questions/12022965/adding-http-headers-to-httpclient

原文：http://www.cnblogs.com/kevin1988/p/6925813.html