The woman, whose identity is suppressed, was on "cinderella leave" with a midnight curfew when she and two friends went to Canberra nightclub Mooseheads about 10pm on May 27, 2016.

The accused, Jack Toby Mitchell, 19, had been at his division's "dining-in night" on campus when the pair texted and he joined her at the Civic club, the court heard.

She told police in a June 2 interview they had met some months before through a mutual friend, but she had recently broken up with her high school boyfriend and had been clear with Mr Mitchell she just wanted to be friends.

They texted often and had spoken on the phone, and she sometimes visited his room when she was in the building to see a friend who was in the same division.

Through tears the woman, 18, described how they left Mooseheads in a taxi and gone back to Mr Mitchell's room at the Campbell campus where they lay down and kissed.

"It wasn't not consensual. Because I just kind of went along with it but I just kept saying I want to go to sleep," she said.

"It's still fuzzy, what happened."

She said she stopped kissing Mr Mitchell and turned over to go to sleep. "Then I came back into conscious ... back into what was happening. My skirt was pulled up.

"He was having sex and I just lay there because it took me a while to work out what was happening.

"It really hurt. I'm still feeling dizzy and I remember trying to push him off ... I was like 'Ow, ow. It's really hurting'.

"He said, 'It's okay, it's okay.' I tried to push him off."

Prompted by police, the woman described herself as "heavily intoxicated" that night. She had not had dinner, she felt confused, dizzy, wobbly and that she didn't have a "barrier" on what she was saying or doing.

She described how she fretted for days over whether to report it because she was worried about her career.

But other cadets had told her what happened was wrong.

Earlier on May 27, the pair had exchanged texts. She told the ACT Supreme Court she was concerned about him being drunk after the dining-in night, which she said was a three-course meal on campus with free, unlimited alcohol.

She told Mr Mitchell in a text he was being "thirsty", which she told the court meant he was being "really persistent".

In opening remarks, Mr Mitchell's barrister Steven Whybrow told the jury there were two distinct versions of the events that night and they were "chalk and cheese".

Mr Mitchell did not deny they had sex but the cadet believed it was consensual. He has pleaded not guilty to the sole count of rape on the indictment.

Mr Whybrow said Mr Mitchell was blown away by the accusation and said texts leading up to the incident showed the pair had liked each other.

"You'll see that Jack was almost Mr Perfect in the way he relates to [the woman]. He clearly likes her, wanting to do the right thing .. not wanting to rush her."

He said if someone woke up and regretted their actions after a night out drinking, such as by dancing or singing karaoke, that didn't mean it hadn't been done of free will.

He told the jury it was only when a friend told the woman that what had happened was wrong, that the woman started to question the night's events.

"Then this snowball gets pushed off the hill ... and it starts rolling," Mr Whybrow said.

But prosecutors suggested the jury would have no trouble concluding beyond reasonable doubt that the woman did not consent to sexual intercourse.

Alternatively, prosecutor Kylie Weston-Scheuber said, if the jury did find there was consent, the Crown said it was the woman's intoxication that caused the consent. Under the legislation, consent caused by intoxication is negated.

She said the court would hear from multiple cadets and about the complaints the woman made to friends and people of authority in the wake of the alleged rape.

Mr Mitchell, in a a slim-fitted blue suit, tie and brown dress shoes, arrived about 20 minutes before the trial began, walking into court with his solicitor, mother and father.

Earlier, presiding judge John Burns warned the jury not to read or listen to media reports of the case, nor talk about the evidence with family and friends.

He said the woman would give evidence by audio-visual link from a remote witness room. Justice Burns said this was standard procedure in the jurisdiction for sexual assault and rape cases and jurors were not to assign any more or less weight to her evidence as a result.

The trial continues.