Flutter

Question

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

我觉得是这样Navigator.of(context).pushNamed('/conta/green');但我不知道如何在页面conta中获取green字符串

因此，通过获取字符串的值，我可以更改 ContaPage 中 appBar 的 backgroundColor 的颜色。

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

您始终可以在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 时在路由中使用该值。像这样：

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，但我首先想到的是 :)

Answer 2

您可以根据需要创建一个 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

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

全局定义一些：

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
   ...
 ),

你必须在依赖项中添加 fluro :

 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，使用方法：

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.',
      ),
    );

Code copied from link.

Answer 5

正在将数据从第 1 页传递到第 2 页

在第 1 页

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

在第 2 页。

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

正在将数据从第二页传回第一页

第 2 页

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

在第1页中，与之前使用的相同，但稍作修改。

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

Flutter - 在路由之间推送和获取值

Flutter - Push and Get value between routes

dart