Flutter v1.12.13+hotfix.5 FocusNode意外行为

Question

我将焦点节点添加到了文本表单字段。在我将flutteer版本升级到v1.12.13+hotfix.5后，flutter focusnode有了意想不到的行为。

  @override
void initState() {
super.initState();

focusNode.addListener(() async {
  if(focusNode.hasFocus)
    {
        Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
    }

    }

}


TextFormField(
  style: TextStyle(color: Theme.of(context).brightness==Brightness.dark?Colors.white:Colors.grey),
  readOnly: true,
  validator: validateField,
  focusNode: focusNode,
  controller: controller,

);

我点击textformfield打开secondPage。但当我关闭secondPage时，会自动打开第二个页面。在我将版本升级到v1.12.13+hotfix.5之后，就发生了这种情况。

v1.12.13+hotfix.5中focusNode的真正用法是什么？

Answer 1

你可以在下面复制粘贴运行完整代码

因为当您从SecondRoute返回时，TextFormField仍然具有foucs，所以您需要执行unfocus

代码片段

focusNode.addListener(() async {
      if (focusNode.hasFocus) {
        await Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => SecondRoute()),
        );
        FocusScope.of(context).requestFocus(new FocusNode());
      }
    });

工作演示

​

​

完整代码

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  final controller = TextEditingController();
  FocusNode focusNode = new FocusNode();

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  void initState() {
    super.initState();

    focusNode.addListener(() async {
      if (focusNode.hasFocus) {
        await Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => SecondRoute()),
        );
        FocusScope.of(context).requestFocus(new FocusNode());
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            TextFormField(
              style: TextStyle(
                  color: Theme.of(context).brightness == Brightness.dark
                      ? Colors.white
                      : Colors.grey),
              readOnly: true,
              //validator: validateField,
              focusNode: focusNode,
              controller: controller,
            ),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

class SecondRoute extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Second Route"),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: () {
            Navigator.pop(context);
          },
          child: Text('Go back!'),
        ),
      ),
    );
  }
}