问GetStorage总是在颤振中返回null

EN

final _userBox = () => GetStorage('User');

class UserPref {

    void call(){
        _userBox.call()..initStorage;
    }

    dynamic setValueInt(String key, int value) {
        return 0.val(key, getBox: _userBox).val = value;
    }

    String setValue(String key, String value) {
        return ''.val(key, getBox: _userBox).val = value;
    }

    dynamic getValueInt(String key) {
        return (-1).val(key,getBox: _userBox).val;
    }

    dynamic getValue(String key) {
        return ''.val(key,getBox: _userBox).val;
    }

    void setUser(User user) {
        ''.val('uname', getBox: _userBox).val = user.uname ?? '';
        (-1).val('gender', getBox: _userBox).val = user.gender ?? -1;
        ''.val('born', getBox: _userBox).val = user.born.toString();
        true.val('enabled', getBox: _userBox).val = user.enabled ?? true;
    }

    User getUser() {
        final String? uname = ''.val('uname',getBox: _userBox).val;
        final int? gender = (-1).val('gender',getBox: _userBox).val;
        final DateTime? born = ''.val('born',getBox: _userBox).val == '' ? null : DateTime.parse(''.val('born',getBox: _userBox).val);
        final bool? enabled = true.val('enabled',getBox: _userBox).val;

        return User(
            uname: uname,
            gender: gender,
            born: born,
            enabled: enabled,
        );
    }
}

///INIT:
@override
void initState() {
    //The init function must be written separately from the read/write function due to being asynchronous. 
    UserPref().call();
}

//OR

Future<void> main() async {
    //await GetStorage.init();
    UserPref().call();
}


///USAGE:

class MyStatefulWidget extends StatefulWidget {
    final Users prefUser = UserPref().getUser();
...
}

//OR

 @override
 Widget build(BuildContext context) {
    final Users prefUser = UserPref().getUser();
    return ...;
 }