Law doesn't seek to punish but to rehabilitate. Act of taking freedom away from the criminal is violent enough. Treating them badly is just a sign of unfair/poor society that cannot maintain (afford to keep) it's promise to be civil to all citizens.
Must justice include punishment? If someone hits me, I'd much rather they take responsibility, apologise, and work on themselves to become a better person, than simply get locked up for a while.
Depending on how hard they hit you, the extent of your injuries, and the circumstances surrounding the assault (premeditated or not, provoked or unprovoked), why not both lock them up and have them work on themselves?