Flutter - 在路由之间推送和获取价值

Question

如何将绿色字符串从 HomePage 页面发送到 ContaPage 页面？

我觉得是Navigator.of(context).pushNamed('/conta/green');，但我不知道如何进入页面contagreen字符串

因此，通过获取字符串的值，我可以例如更改 ContaPage 中 appBar 的背景颜色的颜色。

ma​​in.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

您始终可以在您的主页中创建一个带有绿色的静态变量字符串作为它的值，并在您创建新的 ContaPage 时在您的路线中使用该值。像这样的：

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，但这首先出现在我的脑海中 :)

Answer 2

您可以按需创建MaterialPageRoute 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 3

这有点晚了，但它可能会对某些人有所帮助。我认为最好的方法是使用flutter route项目fluro。

在全局范围内定义一些地方：

final router = Router();

然后定义路线

var contaHandler = Handler(handlerFunc: (BuildContext context, Map<String, dynamic> params) {
  return ContaPage(color: params["color"][0]);
});

void defineRoutes(Router router) {
  router.define("/conta/:color", handler: contaHandler);
}

在MaterialApp 中设置onGenerateRoute 以使用路由器生成器：

 new MaterialApp (
   ...
   nGenerateRoute: router.generator
   ...
 ),

您必须在依赖项中添加荧光：

 dependencies:
     fluro: "^1.3.4"

并通过以下方式或IDE方式进行包升级。

 flutter packages upgrade

Answer 4

Flutter官网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),
      ),
    );
  }
}

注册路线

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link复制的代码。

Answer 5

将数据从第一页传递到第二页

在第一页

// sending "Foo" from 1st page
Navigator.push(context, MaterialPageRoute(builder: (_) => Page2("Foo")));

在第二页。

class Page2 extends StatelessWidget {
  final String string;
  Page2(this.string); // receiving "Foo" in 2nd
}

---

将数据从第二页传回第一页

在第二页

// sending "Bar" from 2nd
Navigator.pop(context, "Bar");

在第一页中，它与之前使用的相同，但几乎没有修改。

// receiving "Bar" in 1st
String received = await Navigator.push(context, MaterialPageRoute(builder: (_) => Page2("Foo")));