Performance problem iterating a resultset

Hello,
I am using JDBC driver for Postgresql to retrieve results from a JSP
page, iterating through the resultset to extract the results and
concatenating it to a string. Everthing is working except for that while I
am iterating through the resultset to generate a string its taking a good
amount of time. Is there a way in Postgresql where I can export the
resultset directly to a xml file?(The data I am receiving from the
database are xml nodes)

Or, Is there a faster way I can retrieve results from the resultset?

Thanks,
-Riyaz