在两个开发板上实现文件的循环收发，一个服务端程序，一个客户端程序，服务端程序先运行，然后在开启服务端，就可以实现文件的循环收发-In both the development of on-board transceiver to achieve the cycle of documents, a server program, a client program, service client program to run first, and then open the service clie