Blocking websites on Android

Is there any way of blocking websites programmatically on an Android device? I would like to have a blacklist of URLs that are populated into a continually running service. When the user running under restricted terms opens a browser, it s开发者_StackOverflow中文版hould check that blacklist.

I've thought of modifying the hosts.allow and hosts.deny files, but those are protected.

I'm pretty sure it is possible on a rooted device - there are some free firewalls. But on a regular device this might not be possible.. I think it would require Kiosk mode in Android