If you've got another service (e.g., tomcat) fighting for port 8080, you can change the port Oracle uses with the following calls:

-- change HTTP port from 8080 to 8083
call dbms_xdb.cfg_update(updateXML(dbms_xdb.cfg_get(), '/xdbconfig/sysconfig/protocolconfig/httpconfig/http-port/text()', 8083));

-- change FTP port from 2100 to 2111
call dbms_xdb.cfg_update(updateXML( dbms_xdb.cfg_get(), '/xdbconfig/sysconfig/protocolconfig/ftpconfig/ftp-port/text()' , 2111));

-- refresh settings
exec dbms_xdb.cfg_refresh;

Tip borrowed from an article by red-database-security.com.