java写的基于socket的文件上传下载，并应用了多线程，服务端的界面也写好，大家都知道界面的编写对于初学者不是件省心的事情，本代码对布局做了一些应用。-written in java socket-based file uploads and downloads and multithreaded application server interface is also written, we all know the interface to write things for beginn