Flutter:如何在不使用按钮的情况下返回数据？

// 返回数据的页面
class ReturnDataPage extends StatelessWidget {
  final Function(String) onDataReceived;

  ReturnDataPage({required this.onDataReceived});

  // 数据准备好后调用回调函数并传递数据
  void _getData() {
    String data = "Hello, World!";
    onDataReceived(data);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Return Data Page')),
      body: Center(
        child: ElevatedButton(
          child: Text('Return Data'),
          onPressed: _getData,
        ),
      ),
    );
  }
}

// 接收数据的页面
class ReceiveDataPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Receive Data Page')),
      body: Center(
        child: ReturnDataPage(
          onDataReceived: (data) {
            // 处理接收到的数据
            print(data);
          },
        ),
      ),
    );
  }
}

// 返回数据的页面
class ReturnDataPage extends StatelessWidget {
  Future<String> getData() async {
    // 模拟获取数据的异步操作
    await Future.delayed(Duration(seconds: 2));
    return "Hello, World!";
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Return Data Page')),
      body: Center(
        child: FutureBuilder<String>(
          future: getData(),
          builder: (context, snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              return CircularProgressIndicator();
            } else if (snapshot.hasError) {
              return Text('Error: ${snapshot.error}');
            } else {
              return Text('Data: ${snapshot.data}');
            }
          },
        ),
      ),
    );
  }
}

// 接收数据的页面
class ReceiveDataPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Receive Data Page')),
      body: Center(
        child: ReturnDataPage(),
      ),
    );
  }
}