de-reference a refcursor in JDBC????

Ok, I wanted to wrap a select statement with a PL/pgsql procedure
(information hiding, etc.)
So I have:

CREATE OR REPLACE FUNCTION user_data_select_all(BIGINT)
RETURNS REFCURSOR AS '
DECLARE
-- parameters
owner_id_p ALIAS FOR $1;

-- local variables
rc REFCURSOR;
BEGIN
OPEN rc FOR SELECT *
FROM user_data
WHERE
owner_id = owner_id_p;
RETURN rc;
END;
' LANGUAGE 'plpgsql' WITH (isstrict);

Now from within psql I get the following:

=> select user_data_select_all(12);
user_data_select_all
----------------------
<unnamed cursor 15>
(1 row)

fetch all in <unnamed cursor 15>;

which lists all of the rows.

How to do the same thing in JDBC. In JDBC I get an exception:
Bad Long <unnamed cursor 1>
at org.postgresql.jdbc2.ResultSet.toLong(ResultSet.java:1498)
at org.postgresql.jdbc2.ResultSet.getLong(ResultSet.java:257)

So the question is can I wrap a select function as return a resultset to

JDBC? How do I dereference the refcursor in JDBC??
How do other interfaces do it? Has anyone ever tried this before?

Richard