如何从另一个StatefulWidget调用StatefulWidget中的函数？

import 'package:flutter/material.dart';

class SourceWidget extends StatefulWidget {
  @override
  _SourceWidgetState createState() => _SourceWidgetState();
}

class _SourceWidgetState extends State<SourceWidget> {
  void sourceFunction() {
    print('Source function called');
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: RaisedButton(
        onPressed: () {
          // 调用目标StatefulWidget中的函数
          TargetWidget.of(context).targetFunction();
        },
        child: Text('Call Target Function'),
      ),
    );
  }
}

class TargetWidget extends StatefulWidget {
  final Function targetFunction;

  const TargetWidget({Key key, this.targetFunction}) : super(key: key);

  @override
  _TargetWidgetState createState() => _TargetWidgetState();

  static _TargetWidgetState of(BuildContext context) {
    return context.findAncestorStateOfType<_TargetWidgetState>();
  }
}

class _TargetWidgetState extends State<TargetWidget> {
  void targetFunction() {
    print('Target function called');
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Target Widget'),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            SourceWidget(),
            TargetWidget(
              targetFunction: () {
                // 在这里实现目标函数的逻辑
                print('Target function called from SourceWidget');
              },
            ),
          ],
        ),
      ),
    ),
  ));
}