该程序的主要功能：服务器端将文件上传到服务器上，然后客户端连接服务器进行文件下载，实现两台计算机之间的文件传输。该程序还能实现聊天功能。-The main functions of the program: the server side to upload files to the server, then connect to the server for the client file to download, to achieve file transfer between two co