ChatClient.java 为客户端程序启动类，负责客户端的启动和退出。
　　Login.java 为客户端程序登录界面，负责用户帐号信息的验证与反馈。
　　Register.java 为客户端程序注册界面，负责用户帐号信息的注册验证与反馈。
　　ChatRoom.java 为客户端程序聊天室主界面，负责接收、发送聊天内容与服务器端的Connection.java 亲密合作。
　　Windowclose 为ChatRoom.java的内部类，负责监听聊天室界面的操作，当用户退出时返回给服务器信息。
　　Clock.java 为客户端程序的一个小程序，实现的一个石英钟功能。(ChatClient.java starts the class for the client program, and is responsible for the startup and exit of the client.
Login.java is the login interface of the client program, which is responsible for the verification and feedback of user account information.
Register.java is the client program registration interface, which is responsible for registration verification and feedback of user account information.
ChatRoom.java is the main interface of the chat room of the client program. It is responsible for receiving and sending Connection.java chat with the server side.
Windowclose is the internal class of ChatRoom.java. It is responsible for monitoring the operation of the chat room interface, and when the user exits, it returns to the server information.
Clock.java is a small program for the client program, and realizes the function of a quartz clock.)