D.K.
It is so normal at their age to express their frustration that way. If she throws a toy, pick it up in front of her and say "we do not throw toys, it is gone for today" and put it up, on the fridge, entertainment center where she can see it but do not give it back to her until the next day.
Also, when they are older and still being hard on toys or throwing them, let them watch Toy Story. I did this with my son and even still I will ask him "are you an Andy or a Sid?" (Sid being the mean boy to his toys) and he will always smile and calm down and say "I am an ANDY!!!"....
When you give it back, say "thank you for not throwing"...and a hug.
If she hits, grab her hand before she makes contact and tell her firmly "not nice, do not hit"..and put her down and away from everyone, in a playpen if need be for time outs. Do not engage in conversation or acknowledge her.
She is frustrated and has little to do with attention but more she doesn't have the verbal means to express herself yet.
I used to say to both of my kids "if you need help, ask mommy but do not throw things out of anger or frustration"...they were older and more apt to comprehend but try and just let her know it is not okay, then reward the times she stops herself.
It isn't lack of attention, it is a normal phase. My daughter at that age used to come in for a hug if frustrated and BITE ME! :) I actually had to resort to thumping lightly on the nose and setting her down and after about a dozen times of that she got the message, hee hee.
My son was the one to throw at toy if it didn't work the way he wanted. I always tried to be empathetic to if they needed help with a toy and not get them upset about it, but also now they are socializing more and she could hurt another child.
Setting her away when she does it and rewarding when she doesn't will help her make the connection.
Even saying things like "I know you are angry but we do not throw things!", Acknowledging feelings is key however also not tolerating agression during upset is too. Good luck, we all have been there with this one I assure you! :)