Not sure if it's "normal", but...
I would prefer not to persist data into a database from a
JSP or (controller) servlet, but use an intermediate object which models the real world entity. For instance, call it "user".
Now this object can be anything - if you're using a two tier model, probably a data aware bean to make it easy to access from a JSP. If you're using n-tier then it might be an
EJB.
Knowledge of the precise requirements for the attributes of that object should be isolated in the object class. In other words, the "setZip" method of the "User" class would indicate an error - throw a suitable exception, say - when you would try to set an illegal zip code. (Of course, "User" may delegate this internally to a "ZipCode" instance, and "ZipCode" may internally use a "validate" method).
The controller would catch these exceptions and turn them into comprehensible error messages. If you don't mind reporting on a single error at a time, one try block with a couple of catches can do the job.
- Peter