Flutter中使用GlobalKey获取子widget中数据

可以获取子控件state、widget、context

class APPHomePage extends StatefulWidget {
  @override
  _APPHomePageState createState() => _APPHomePageState();
}
class _APPHomePageState extends State<APPHomePage> {
  final GlobalKey<_TestChildState> testChildKey = GlobalKey();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: TestChild(key: testChildKey),
      floatingActionButton: FloatingActionButton(onPressed: (){
        print(testChildKey.currentState.widget.name);//获取子控件数据
        print(testChildKey.currentState.message);//获取子控件state中的数据
        testChildKey.currentState.test();//调用子控件方法
      }),
    );
  }
}

子widget

class TestChild extends StatefulWidget {
  final String name = "cy";
  TestChild({Key key}):super(key : key);
  @override
  _TestChildState createState() => _TestChildState();
}

class _TestChildState extends State<TestChild> {
  final String message = "hello world";
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text("data"),
    );
  }
  void test(){
    print("test");
  }
}

打印:

flutter: cy
flutter: hello world
flutter: test