我研究了一下后发现了这个
https://pub.dev/packages/location_plus

Future<dynamic> getCurrentLocation() async {
var result = await LocationPlus.getCurrentLocation();
setState(() {
    print(result);
    _locality = result['locality'];
    _postalCode = result['postalCode'];
    _administrativeArea = result['administrativeArea'];
    _country = result['country'];
    _latitude = double.parse(result['latitude']);
    _longitude = double.parse(result['longitude']);
    _ipAddress = result['ipAddress'];
});
}

字符串
the _postalCode是邮政编码