需要启动两个命令窗口一起使用，当本练习中的服务器端启动之后，运行本练习的客户端程序，则可以看到服务器给客户端发送的字符串显示。-Need to start two command window are used together, when the server startup in practice, after practice run this client program, can see the server to the client send string display.