I´ve noticed a few more details:
*In my oracle database, the srid for spatial tables and metadata is
23030 (I´ve also tried NULL), which isn´t recognized by GeoServer, it
shows me a 0 in the srs text control.
That code is not valid in Oracle Spatial Metadata Table. You need to check out codes in table MDSYS.CS_SRS to get the valid one (in think for UTM 30N is 82337)
*When I´m creating a feature type, GeoServer still doesn´t recognize my
geometry column, it´s filled in blank.
That is no problem at all, I get the same, and it Works fine either in WMS and WFS
* I use udig throug geoserver-wms and it works fine, but if I use
geoserver-wfs to obtain data from my table, it´s correctly identified,
but when I load it, it gives error:
The error is because an incorrect SRID (23030) which does not exist in Oracle Spatial CS_SRS Table.