Process deployment has improved a lot with the latest few releases of the jbpm 3.1 branch. You can do it with the graphical process designer (as before), but there is a possibility now to save the *.par archive in a particular location. Starting with 3.1alpha_something there is also an upload servlet included in the default webapp. The GPD uses this servlet to do the deployment, but you can also do this step manually using the deploy.html page of the default webapp.
For the 3.0.x versions, you can also use the GPD, but it does not save the processarchive somewhere and does not use this upload servlet. If you need the archive, you should rely on the zip and deploypar ant tasks to first create the process archive as you describe it and then deploy it directly to the database.
Thanks Kone !
I've spent much time on jbpm 3.0.x version,should I give up it ,and try 3.1 version ? Need your suggestion! Thanks again!