如何将输入值从扩展子小部件返回到flutter中的父小部件

class ParentWidget extends StatefulWidget {
  @override
  _ParentWidgetState createState() => _ParentWidgetState();
}

class _ParentWidgetState extends State<ParentWidget> {
  String inputValue = '';

  void updateInputValue(String value) {
    setState(() {
      inputValue = value;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        ChildWidget(callback: updateInputValue),
        Text('输入值：$inputValue'),
      ],
    );
  }
}

class ChildWidget extends StatefulWidget {
  final ValueChanged<String> callback;

  const ChildWidget({required this.callback});

  @override
  _ChildWidgetState createState() => _ChildWidgetState();
}

class _ChildWidgetState extends State<ChildWidget> {
  final TextEditingController _controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextField(controller: _controller),
        ElevatedButton(
          onPressed: () {
            widget.callback(_controller.text);
          },
          child: Text('返回'),
        ),
      ],
    );
  }
}