记录一些正则匹配

String urlRegExp = r'(?:(?:https?|ftp)://)?[\w/-?=%.]+.[\w/-?=%.]+';

String hashtagRegExp = r'(#+[a-zA-Z0-9(_)]{1,})';

String userTagRegExp = r'(?<![\w@])@([\w@]+(?:.!+)*)';

String emailRegExp =

r"([a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9]+\.[a-zA-Z]+)";