将数据转发到下一个屏幕

Question

在学习Flutter时，我已经开始导航。我想在屏幕之间传递数据，类似于passing data between Activities in Android和passing data between View Controllers in iOS。如何在Flutter中做到这一点？

将数据转发到下一个屏幕

要将数据发送到下一个屏幕，请执行以下操作：

使SecondScreen构造函数为您要发送给它的数据类型采用一个参数。在此特定示例中，数据定义为String值，并在此处使用this.text进行设置。
```
class SecondScreen extends StatelessWidget {
  final String text;
  SecondScreen({Key key, @required this.text}) : super(key: key);

  ...
```
然后使用Navigator小部件中的FirstScreen将路由推送到SecondScreen小部件。您将要发送的数据作为参数放入其构造函数中。
```
Navigator.push(
    context,
    MaterialPageRoute(
      builder: (context) => SecondScreen(text: 'Hello',),
    ));
```

main.dart的完整代码在这里：

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: 'Flutter',
    home: FirstScreen(),
  ));
}

class FirstScreen extends StatefulWidget {
  @override
  _FirstScreenState createState() {
    return _FirstScreenState();
  }
}

class _FirstScreenState extends State<FirstScreen> {

  // this allows us to access the TextField text
  TextEditingController textFieldController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('First screen')),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [

          Padding(
            padding: const EdgeInsets.all(32.0),
            child: TextField(
              controller: textFieldController,
              style: TextStyle(
                fontSize: 24,
                color: Colors.black,
              ),
            ),
          ),

          RaisedButton(
            child: Text(
              'Go to second screen',
              style: TextStyle(fontSize: 24),
            ),
            onPressed: () {
              _sendDataToSecondScreen(context);
            },
          )

        ],
      ),
    );
  }

  // get the text in the TextField and start the Second Screen
  void _sendDataToSecondScreen(BuildContext context) {
    String textToSend = textFieldController.text;
    Navigator.push(
        context,
        MaterialPageRoute(
          builder: (context) => SecondScreen(text: textToSend,),
        ));
  }
}

class SecondScreen extends StatelessWidget {
  final String text;

  // receive data from the FirstScreen as a parameter
  SecondScreen({Key key, @required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Second screen')),
      body: Center(
        child: Text(
          text,
          style: TextStyle(fontSize: 24),
        ),
      ),
    );
  }
}

将数据传递回上一屏幕

将数据传回时，您需要执行以下操作：

在FirstScreen中，使用Navigator以SecondScreen方法推入（启动）async，并等待结果在返回时返回完成。

final result = await Navigator.push(
    context,
    MaterialPageRoute(
      builder: (context) => SecondScreen(),
    ));

在SecondScreen中，包含要在弹出Navigator时作为参数传递回的数据。
```
Navigator.pop(context, 'Hello');
```
然后FirstScreen中的await将结束，您可以使用结果。
```
setState(() {
  text = result;
});
```

以下是main.dart的完整代码，供您参考。

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: 'Flutter',
    home: FirstScreen(),
  ));
}

class FirstScreen extends StatefulWidget {
  @override
  _FirstScreenState createState() {
    return _FirstScreenState();
  }
}

class _FirstScreenState extends State<FirstScreen> {

  String text = 'Text';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('First screen')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [

            Padding(
              padding: const EdgeInsets.all(32.0),
              child: Text(
                text,
                style: TextStyle(fontSize: 24),
              ),
            ),

            RaisedButton(
              child: Text(
                'Go to second screen',
                style: TextStyle(fontSize: 24),
              ),
              onPressed: () {
                _awaitReturnValueFromSecondScreen(context);
              },
            )

          ],
        ),
      ),
    );
  }

  void _awaitReturnValueFromSecondScreen(BuildContext context) async {

    // start the SecondScreen and wait for it to finish with a result
    final result = await Navigator.push(
        context,
        MaterialPageRoute(
          builder: (context) => SecondScreen(),
        ));

    // after the SecondScreen result comes back update the Text widget with it
    setState(() {
      text = result;
    });
  }
}

class SecondScreen extends StatefulWidget {
  @override
  _SecondScreenState createState() {
    return _SecondScreenState();
  }
}

class _SecondScreenState extends State<SecondScreen> {
  // this allows us to access the TextField text
  TextEditingController textFieldController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Second screen')),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [

          Padding(
            padding: const EdgeInsets.all(32.0),
            child: TextField(
              controller: textFieldController,
              style: TextStyle(
                fontSize: 24,
                color: Colors.black,
              ),
            ),
          ),

          RaisedButton(
            child: Text(
              'Send text back',
              style: TextStyle(fontSize: 24),
            ),
            onPressed: () {
              _sendDataBack(context);
            },
          )

        ],
      ),
    );
  }

  // get the text in the TextField and send it back to the FirstScreen
  void _sendDataBack(BuildContext context) {
    String textToSendBack = textFieldController.text;
    Navigator.pop(context, textToSendBack);
  }
}

Answer 2

获得完善的解决方案：

从第一个屏幕导航至其他位置：

Navigator.pushNamed(context, "second",arguments: {"name" : 
  "Bijendra", "rollNo": 65210});
},

在构建方法的第二个屏幕上显示为：

@override
Widget build(BuildContext context) {
    final  Map<String, Object>rcvdData = ModalRoute.of(context).settings.arguments;
    print("rcvd fdata ${rcvdData['name']}");
    print("rcvd fdata ${rcvdData}");

    return Scaffold(appBar: AppBar(title: Text("Second")),
      body: Container(child: Column(children: <Widget>[
      Text("Second"),
    ],),),);

}

Answer 3

最简便的方法

FirstPage.dart

 Navigator.push(
          context,
          MaterialPageRoute(
              builder: (context) => PasswordRoute(usernameController)));

// usernameController是字符串值，如果要传递多个值，请全部添加

SecondPage.dart

class PasswordRoute extends StatefulWidget {
  final String usernameController;//if you have multiple values add here
PasswordRoute(this.usernameController, {Key key}): super(key: key);//add also..example this.abc,this...

  @override
  State<StatefulWidget> createState() => _PasswordPageState();
}

class _PasswordPageState extends State<PasswordRoute> {
 @override
  Widget build(BuildContext context) {
...child: Text(widget.usernameController);
}
}

Answer 4

通过在构造函数中传递变量，此解决方案非常简单：

第一页：

Navigator.of(context).push(MaterialPageRoute(builder:(context)=>SecondPage('something')));

第二页：

class SecondPage extends StatefulWidget {
  String something;
  SecondPage(this.something);
  @override
  State<StatefulWidget> createState() {
    return SecondPageState(this.something);
  }
}
class SecondPageState extends State<SecondPage> {
  String something;
  SecondPageState(this.something);
  @override
  Widget build(BuildContext context) {
   return Scaffold(
    appBar: AppBar(
    //now you have passing variable
    title: Text(something),
   ),
   ...
  }

Answer 5

第一个屏幕： //将数据发送到第二个屏幕

 Navigator.push(context, MaterialPageRoute(builder: (context) {
                          return WelcomeUser(usernameController.text);

                          }));

第二屏幕： //从第一个屏幕获取数据

 final String username;
  WelcomeUser(this.username);

//使用数据显示

body: Container(
    child: Center(
      child: Text("Welcome "+widget.username,
      textAlign: TextAlign.center,
      ),
    ),
  ),

Answer 6

以上答案对于小型应用程序很有用，但是如果您想消除持续担心小部件状态的麻烦，则Google提供了Provider软件包。 https://pub.dev/packages/provider

看看其中的内容，或观看Andrea Bizzotto的以下视频： https://www.youtube.com/watch?v=MkFjtCov62g //提供者：基本指南 https://www.youtube.com/watch?v=O71rYKcxUgA&t=258s //提供者：简介

了解如何使用Provider软件包，您将终生：）

Answer 7

1）从您要推送的位置：

onPressed: () async {
                        await Navigator.pushNamed(context, '/edit',
                            arguments: userData);
                        setState(() {
                          userData = userData;
                        });}

2）从您要弹出的位置：

    void updateData() async{
    WorldTime instance = locations;
    await instance.getData();
    Navigator.pop(context, userData);
  }

Answer 8

如果使用get软件包，请尝试此。

检查获取软件包passing data with get package

在Flutter中在屏幕之间传递数据

8 个答案:

将数据转发到下一个屏幕

将数据传递回上一屏幕

通过在构造函数中传递变量，此解决方案非常简单：