Java: How URLConnection treats completed TCP connection?

When I use URLConnection to do some HTTP requests, I could only close 开发者_如何学GoInputStream and OutputStream, but not the socket.

Does the class automatically close the socket? How does it do it? Will the server return a FIN or something else?

If I produce many threads including each URLConnection in them, will it automatically reuse the socket? I caught some packages, it shows about every 3 connections share 1 socket.

It pools the socket for possible future reuse within a short period of time, I think 5 or 15 seconds. HttpURLConnection.disconnect() is the only thing that actually closes it.