COPy command question

Hi,
A question about the Postgresql's COPY command.

This is the syntax of this command from the manual
COPY tablename [ ( column [, ...] ) ]
FROM { 'filename' | STDIN }
[ [ WITH ]
.....
I want to migrate my tables from Oracle to Postgres.
The COPY FROM command can take input from 'file' or 'STDIN'.
Is it possible for the COPY command to take its input from a
java program(which contains the oracle resultset) or any other way?

I know I could get the Oracle rows in a csv format but
Im trying to get it done without any file in between ?

In short is it possible to use this 'COPY' command to migrate my tables'
data from Oracle to Postgresql without using any file in between?

Thanks
Sharmila