System control with java, and networking in jave

Question

Hi, just a couple of questions.
Ill start witht the networking query. Ive been making a basic network chat program using sockets. The text is transfered through the sockets as strings read in from text field on the interface
eg
kkSocket = new Socket("xxx.xxx.xxx.xxx", 80);
out = new PrintWriter(kkSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream()));
String fromUser = (ba.text());
out.println(fromUser);
All this works fine, i want to impliment file transfer into the app, but im clueless how to transfer anything other than a basic string over a socket, let alone send it to a specific location on the client computer. Any help / advice would be well recieved.
Also, as i have basic code, that can connect computers, and send messages between them, i was wondering how i control some of the system functions, like executing files, opening / closing cd tray etc through java. As with this, i could create a mini remote control application.
Again, any help on this (or even a pointer to relavent things in the java api) would be fantastic as the more i can understand the more inventive i can be when coding
Cheerz

Answer 1

You seem to manage well even though you're posting to New To Java Technology, I've seen far worse questions in ALT even...
All this works fine, i want to impliment file transfer into the app, but im clueless how to transfer anything other than a basic string over a socket, let alone send it to a specific location on the client computer.To send files/binary data, you would use a BufferedInputStream (remember Streams are for binary data, Readers/Writers are for text) in a similar way you're using PrintWriter and BufferedReader now.
It could go a bit like this (invent your own protocol):
User1 sends a String that says: FILE C:\directory\file
User2 receives the String and prepares to save a file to the specified directory.
User1 sends the binary data to User2.
User2 reads the binary data and writes it in the file.
Controlling system functions in Java can be tricky, so you might not get all the functionality in your program that you want. Running programs can be done through System.exec(), but the CD tray might be impossible even.