An advice please....?

there is a guy I know 4 years from school, and he keeps sending me mixed signals. Everything began 3 years ago when he sent me a note telling me he likes me. He is perhaps one of the hottest boys of the school and he is kinda poppular.I am well..... normal, shy, and nice girl and I'm not that bad looking. Cause he is generally social with other girls at the beginning I thought that he was kidding , but he continued to do little things such as giving me " knowing looks ", pick up things for me, always initiate any conversation, asking me of homework or to borrow him a pencil, and "accidentaly" bump onto me. Sometimes he pretends that I don't exist, and sometimes he stares at me, and he even had asked me if I have a boyfriend, in a playful tone .( of course I didn't tell him ).Yet he has never asked me out, .During these three years i'm still trying to figure out if he really likes me. And if he does, then why he doesn't ask me out ? And I, being confused of his behavior, I'm afraid to show any sign of attraction to him because I'm not sure of his feelings, and of course I don't want to get hurt. I hear that he doesn't have any girlfriend, although he has many "admirers " The unusual is that even if he didn't ask me out, he continued to court me throughout these 3 years. So..... what d' you think is happening here ? Does he like me ?