颤动 - 在路线之间推送和获取价值

Question

如何将HomePage页面中的绿色字符串发送到ContaPage页面？

我认为是这样Navigator.of(context).pushNamed('/conta/green');但我不知道如何进入页面中conta的green字符串

因此,通过获取字符串的值,我可以例如更改appBarin 的backgroundColor的颜色ContaPage.

main.dart

import "package:flutter/material.dart";

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: "MyApp",
      home: new HomePage(),
      routes: <String, WidgetBuilder> {
        '/home': (BuildContext context) => new HomePage(),
        '/conta': (BuildContext context) => new ContaPage()
      },
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: new Color(0xFF26C6DA),
    ),
    body: new ListView  (
      children: <Widget>[
        new FlatButton(
          child: new Text("ok"),
          textColor: new Color(0xFF66BB6A),               
          onPressed: () {
            Navigator.of(context).pushNamed('/conta');
          },
        ),
      ],
    )
  );
}

class ContaPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: new Color(0xFF26C6DA),
    ), 
  );
}

Answer 1

您可以创建MaterialPageRoute按需并将参数传递给ContaPage构造函数.

import "package:flutter/material.dart";

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: "MyApp",
      home: new HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: new Color(0xFF26C6DA),
    ),
    body: new ListView  (
      children: <Widget>[
        new FlatButton(
          child: new Text("ok"),
          textColor: new Color(0xFF66BB6A),
          onPressed: () {
            Navigator.push(context, new MaterialPageRoute(
              builder: (BuildContext context) => new ContaPage(new Color(0xFF66BB6A)),
            ));
          },
        ),
      ],
    )
  );
}

class ContaPage extends StatelessWidget {
  ContaPage(this.color);
  final Color color;
  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: color,
    ),
  );
}

Answer 2

Flutter网站上已经给出了更好的解决方案，如何使用：

参数

class ScreenArguments {
  final String title;
  final String message;

  ScreenArguments(this.title, this.message);
}

提取参数

class ExtractArgumentsScreen extends StatelessWidget {
  static const routeName = '/extractArguments';

  @override
  Widget build(BuildContext context) {
    final ScreenArguments args = ModalRoute.of(context).settings.arguments;
    return Scaffold(
      appBar: AppBar(
        title: Text(args.title),
      ),
      body: Center(
        child: Text(args.message),
      ),
    );
  }
}

注册路由

MaterialApp(
  //...
  routes: {
    ExtractArgumentsScreen.routeName: (context) => ExtractArgumentsScreen(),
    //...
  },     
);

导航

Navigator.pushNamed(
      context,
      ExtractArgumentsScreen.routeName,
      arguments: ScreenArguments(
        'Extract Arguments Screen',
        'This message is extracted in the build method.',
      ),
    );

从链接复制的代码。

Answer 3

您总是可以在HomePage中创建一个绿色的静态变量String作为它的值,并在创建新的ContaPage时在路径中使用该值.像这样的东西:

import "package:flutter/material.dart";

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: "MyApp",
      home: new HomePage(),
      routes: <String, WidgetBuilder> {
        '/home': (BuildContext context) => new HomePage(),
        '/conta': (BuildContext context) => new ContaPage(HomePage.color)
      },
    );
  }
}

class HomePage extends StatelessWidget {

  static String color = "green";

  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: new Color(0xFF26C6DA),
    ),
    body: new ListView  (
      children: <Widget>[
        new FlatButton(
          child: new Text("ok"),
          textColor: new Color(0xFF66BB6A),               
          onPressed: () {
            Navigator.of(context).pushNamed('/conta');
          },
        ),
      ],
    )
  );
}

class ContaPage extends StatelessWidget {

  ContaPage({this.color})
  String color;

  @override
  Widget build(BuildContext context) => new Scaffold(
    appBar: new AppBar(
      backgroundColor: new Color(0xFF26C6DA),
    ), 
  );
}

可能有更好的解决方案,但这首先突然出现在我脑海中:)