exporting DDL of all views Oracle
Try this for DBMS_METADATA.GET_DLL:

set long 200000 pages 0 lines 150
spool vw.sql
select 
   dbms_metadata.GET_DDL('VIEW',u.view_name,DECODE(u.owner,'SYS','',owner)) 
from 
   all_views u
where 
   owner IN ('HR','SCOTT') 
order by owner,view_name ;
spool off


You can either include the schemas you are interested in or exclude the schemas you do not want in the "owner IN" clause.