区分大小写??? 你是要大写，还是小写??给你个大写的吧..../^(?!\d{6,8}$)[A-Z0-9]{6,16}$/
match ^[0-9a-zA-Z]{6,19}$andnot match ^[0-9]{6,9}$
str.matches("^[A-Za-z0-9]{6,19}") && !str.matches("[0-9]{6,9}")
