1- The class has been canceled. - This sounds very natural, it means the class was canceled in the past and I'm thinking about it now. For example, this is normally the time to go to class.
2 - The class had been canceled - This sounds like something has changed. Maybe the class is not canceled now, or it was moved to a different time. It was canceled in the past, but now it isn't it.
'The class is canceled' - has almost the same meaning as the class has been canceled.
I just wrote up an article about present perfect tense vs. past perfect tense. That might help as well.
Student or Learner