What do i do with my dominate akita, he won't stop jumping on me.?

i have a 6 month old akita. whenever i go outside to do something he'll jump on me with his paws on my chest which is painfull becuase he is very big and he has sharp claws. if i try to put him down he'll do it again right away. how do i stop him? oh and if i ignore him he'll bite my ankles, how do i stop him!?