在发布starttls之后将Java套接字升级为加密

I want my app to talk to the server without encryption before issuing a STARTTLS and then upgrade the socket to be encrypted after that. Can I connect to a port (E.g., 5222) and use STARTTLS to request TLS using java? If so, which Socket object should I use for that? I want my app to talk to the server without enc