一个java写的聊天室，分服务器端和客户端，服务器端实现后台管理，客户端有登录功能，还有私聊等功能。-Write a java chat room, and server-side and client-side, server-side implementation management background, the client has a login function, as well as private chat and other functions.

AuthProvider is an abstract superclass for Java Security {@code Provider which provide login and logout.