Jackie was raised in a Chinese Opera School and
the man who ran it was a Kung Fu Master and made his
students learn KF for health,athleticism and discipline.
His older brother in the school was Sammo Hung. I
read an interview with Sammo where he says the style
is basically Shaolin Kung Fu,chunks from a bunch of
other Shaolin styles. He did that for many
years,starting when he was a very young kid,so if Jackie knows
Hapkido,he learned it after he knew KF. And Jackie has said
he freelanced the drunken style in the flicks, but I
know that there is a Drunken Longfist Kung Fu form
because a woman who lives near me teaches it.