What type of lenses does a slr lens adapter work on?

I'm getting a 7D soon but I have two Nikon lenses, and they are both automatic and I would like to use them on my new 7D if possible. 1) Is this at all possible, 2) If so.how?
My Nikon lenses are a Tamron 70 - 300mm and a Nikon 18 - 105mm, so can a lens adaptor be used to place them onto my 7D canon slr?
Thanks

Added (1). I know you can get adapters.

No. The Nikon mount lenses are not adaptable to Canon EOS or vice versa.

There's no adaptor for Nikon to Canon or vice versa
why not get a Nikon bodt if you want to use these lenses?

Even if you could very often the adaptor doesn't allow the camera and lens to "talk" so auto focus,
exposure and focus all go away.

Besides that, being the owner of one Tamron lens - I won't buy another, any lens other than Canon and above will degrade the quality of this very fine camera. Best bet - buy Canon lenses for this camera.

Yes it is indeed possible, but the lens won't autofocus and you have to set the aperture value manually (If it's possible [depends on the lens], if not, you're stuck with the widest aperture). But I think you'd be better off selling those two lenses and get some canon glass. I'd recommend the 15-85mm IS USM as a general purpose lens and the 50mm 1.8, a fast prime lens (wide aperture = nice blurry background + better lowlight capabilities)

edit: For all the people saying there's no adapter for nikon lens to canon body, have a look at this: http://www.amazon.com/...002JWYAXA/

There's a Nikon to canon adapter, but it is not automatic. It is for old, manual focus and manual aperture ring lenses. There will be no way to operate the lens on your body.

The only solution is to buy a Nikon body or trow away the lenses and buy all new Canon lenses.

Yes you can get adapters… But

You will lose 1-2 stops of light
lose all chance of autofocus
possibly lose metering

In other words, it's pretty much useless. You can go with Nikon to make use of your lenses, or sell your lenses and get lenses for the 7D