说明：  套接字编程，实现服务器与客户端之间的聊天。可用JCreat运行，先运行服务器端程序，后运行客户端程序。此为服务器端源码
(Socket programming, server and client chat between. JCreat can be used to run, first run the server-side process, after running the client program. This is the server-side source)