flutter - 使用其有状态小部件访问状态类的方法？

Question

我在 state 类中有一个方法，但我需要使用它的小部件类引用在外部访问该方法，

class TestFormState extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _testState();
  }
}

class _testFormState extends State<TestFormState> {
  int count = 1;

  @override
  Widget build(BuildContext context) {
    return Center(
        child: Container(
        color: Colors.green,
            child: Text("Count : $count"),
        ),
    );
  }

  clickIncrease(){
    setState(() { count += 1; });
  }
}

我需要在另一个小部件中访问上述小部件的 clickIncrease，如下面的代码，

class TutorialHome extends StatelessWidget {

    TestFormState test;

  @override
  Widget build(BuildContext context) {
    // Scaffold is a layout for the major Material Components.
    return Scaffold(
      body: Column(
         children: <Widget>[
            test = TestFormState(),
            FlatButton(
               child: Text("Increase"),
               onPressed: (){
                  test.state.clickIncrease(); // This kind of thing I need to do
               },
            ),
         ]
      ),
    );
  }

我写了上面的代码只是为了演示这个问题。

Answer 1

我有一个技巧，但我不知道这是否是一种不好的做法。

class TestFormState extends StatefulWidget {

  _TestFormState _testFormState;

  @override
  State<StatefulWidget> createState() {
    _testFormState = _TestFormState();
    return _testFormState;
  }
}

class _TestFormState extends State<TestFormState> {
  int count = 1;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        color: Colors.green,
        child: Text("Count : $count"),
      ),
    );
  }

  clickIncrease(){
    setState(() { count += 1; });
  }
}

现在，您可以在这里访问它:

class TutorialHome extends StatelessWidget {

  TestFormState test;

  @override
  Widget build(BuildContext context) {
    // Scaffold is a layout for the major Material Components.
    return Scaffold(
      body: Column(
          children: <Widget>[
            TextButton(
              child: Text("Increase"),
              onPressed: () {
                test._testFormState
                    .clickIncrease(); // This is accessable
              },
            ),
          ]
      ),
    );
  }
}

我建议看看 ValueNotifier