If you want to upload through http, you can go to www.servlets.com to get the source (how to handle the multiform of post).
If you want to upload/download through TCP, just use java.net API.
If you want to upload/download through TCP, just use java.net API.
里面有upload类,能很方便的上传文件。欢迎光临Java,J2EE论坛( http://letsjava.yeah.net )。
http://www.minij2ee.com/
下载则分为HTTP和FTP两种,看看协议,很简单的