java:https://docs.oracle.com/javase/specs/jls/se10/html/index.html
https://www.codota.com/code/
java:https://docs.oracle.com/javase/tutorial/networking/index.html
RFC:https://tools.ietf.org/html/rfc2616
http://zhangtielei.com/posts/blog-programmer-learn.html
http://zhangtielei.com/