如何在Flutter中对状态构造器变量进行操作？

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    return StatefulBuilder(
      builder: (BuildContext context, StateSetter setState) {
        return Column(
          children: [
            Text('Counter: $_counter'),
            RaisedButton(
              child: Text('Increment'),
              onPressed: () {
                setState(() {
                  _counter++;
                });
              },
            ),
          ],
        );
      },
    );
  }
}