PHP would need to talk to an FTP server on the other end. Most home users are not running an FTP server so you will end up having connectivity issues.
Java is used because it can run on the client (JavaScript can do this), can do file and network handling (JavaScript can't do the file handling).
PHP is strictly server side and has no way to interact with a client unless the client interacts with it instead. One option would be to have the client upload 10, 25, and 100k files and you may be able to have PHP time the various uploads. But this requires the user to do some work.
The only other thing I can think of is if you do something with sockets, but you'd still need some sort of client app to talk to your socket server.