I have long hair.

It is correct English to say "I have long hair." Also, It is both grammatically correct and colloquial to say "I've got long hair." However, in SOME instances "I've got" implies a transaction. Example: I have a cinnamon bun= shows possession only (it is in my hand). I've got a cinnamon bun= implies you purchased it from someone or perhaps stole it from your father without him knowing. Either way, a transaction happened. That said, you could say "I've got long hair" and nobody would think it sounded weird. There are no instances where we say "I'm got (something)."

I prefer,i have along hair[emoji]

U say " I've (short for I have) got long hair. " Or " I have long hair."