Velocity based tools
Reference to the ResourceLoader object class can be passed to a Velocity template in it's context:
ResourceLoader rb = new ResourceLoader("_org.sakaiproject.tool.foobar.bundle.Messages_"); context.put("tlang", rb );
Then any strings can be referenced as standard velocity variables:
$tlang.getString("foo");
For Sakai 2.8 and newer you can also supply parameters to getFormattedMessage such as:
$tlang.getFormattedMessage("foo", $value)