Can my landlord just enter my apartment at any time without prior notice?

I know laws and practices vary from state to state; I live in Oklahoma. Anyway, the apartment next to mine was being readied for the next tenant, and apparently there was a plumbing issue with that apartment (not mine) for which my landlord had scheduled a plumber to come look at. Upon examination, the plumber had noticed that something was connected to my apartment, so he had to shut my water off to fix the problem. Well, sometime during the plumber's visit, my landlord was told they needed to verify that the water was running properly in my apartment, and so while I was there, sleeping, she entered without knocking (she later said because she didn't know I was home) and went to my kitchen and bathroom and turned my faucets on and left. She returned about ten or fifteen minutes later to turn them off, and woke me up in the process. I received no notice that she'd be even possibly entering my apartment, only that I'd be without water between 7 and 8 am. This is the first, but unfortunately not the last unpleasant experience I've had as a tenant. I've also been explained to by my landlord that it is very important I pay my electric bill on time because some way or another, the electricity powering her maintenance garage is connected to my apartment- something I had not been made aware of until after signing my lease. It is not mentioned in the lease, and I am not reimbursed. There have just been numerous occurrences such as these, and I'm only three months in on a year lease. Is there a way to amicably break the lease, or will I be expected to suffer through the next eight and half months?I