I'm not sure I understand the question. Are you trying to write the .jsp source on the fly, like an admin screen? You can write (using the java.io package) out to disk using a FileWriter, usually wrapped in a BufferedWriter to improve performance. See
Sun IO tutorial for some pointers, and don't forget to flush() the BufferedWriter before close()ing it.
Just remember, the ability to write and execute server code from a web interface could be very badly abused (Runtime.exec("some bad code"), for starters) and should be protected accordingly.
HTH,
Chris
