Java servlets, JDBC

I am trying to connect to an oracle8i database through a web application (servlet), I am getting the following error: Couldn’t get a connection: Io exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=135294976)(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4)))). Trying again.

Can any one help please?
Thanks.