说明：  本程序是用JAVA写的，是一个算是简单的聊天程序，实现了客户机跟服务器的对话。可作为其他程序的子程序使用和作为JAVA初学者的参考程序。
(this program is written in Java, is regarded as a simple chat program, to achieve a client with the server dialogue. Other procedures can be used as a subroutine and use as a reference Java beginners procedures.)