hi,
define a base class which handles all error related
operations. get Error code from E.getErrorCode() in Catch
block and then throw that error to action class.
Example.
Error code 00001: is defined for Unique constraint
voilation. for this 
catch{
  if(errorCode == 00001){
    throw new UniqueKeyException();
  } 
}
// this unique exception is userdefined exception in my
framework.

and catch this exception in your action class. and be
remember in your struts-config file action tag define
input="/ErrorPage.do" property. then only it redirects to
that page in what u defined in input tag action path.

if any thing regarding this one feel free to mail me.
Thanks a lot