Insert code snippets with proper indentation?

Is there a way, a special syntax, for inserting code snippets? For instance, my users may want to add a fragment of Java or Groovy code and the alignment (the tabs or spaces) are always removed at the beginning of the line. I'd like something a bit like a

 tag, in a way. But I don't need syntax highlighting or anything like that: just keeping the indentation. Is there something like that that I've missed?