Why does my cat whine at the door when I'm in the bathroom?

[Michelle]

We just got our 2 year old cat, John, from an animal shelter about 9 months ago. He's a great cat, except for the fact that he's terribly obsessed with us. He's also obsessed with the bathroom. Everytime one of us go in the bathroom to shower or use the toilet, he whines and paws at the door. Especially when we're showering. He goes as far as to claw at the carpeting by the door and has actually pulled some of it up in the process. When we open the door to the bathroom, he runs in the sits by the tub or sometimes in it. He loves the water coming out of the faucet. We don't mind the fact that he likes to hang out by the tub, since he's not hurting anything, but the whining at the door is getting a little annoying and the clawing is ruining the carpet. We have tried a spray bottle (which works for a short time), a scratching post (which he really doesn't like), and differential reinforcement (giving attention when he is being good), but nothing seems to break him of his bathroom obsession. If anyone could give us tips to help, it would be great!