JDBC - setting PG variables in URL

Hi,
Is it possible to set any of postgre variables in JDBC conection URL?

Example:
"jdbc:postgresql://localhost:/dbname?pgvar1=value2&pgvar2=value2"

Is this or simular construction plausible? We tried it, but it didn't work.
OR - question could be put this way: How to set internal postgre variables
(like search_path etc.) from Java2 enviroment using JDBC?

Thanks for any hints.

Regards,
Jan