小贝子编程

Flutter web底部导航栏，支持url更新和超链接



我一直在网上搜索年龄，寻找一个支持以下功能的flutter应用程序示例：

  1. 持久底部导航栏
  2. 导航器支持持续存在状态的每个底部导航栏项目
  3. 导航员在导航时更新flutter web中的URL
  4. 导航器支持在flutter web中超链接到特定页面。例如，如果用户键入www.myappdomain.com/#/profile，则会导航到配置文件页面。或者他们键入www.myappdomain.com/#/profile？id＝123他们被导航到用户123的配置文件页面

我已经能够用以下代码实现第1点和第2点：

import 'package:flutter/material.dart';
void main() {
runApp(BaseApp());
}
class BaseApp extends StatefulWidget {
@override
_BaseAppState createState() => _BaseAppState();
}
class _BaseAppState extends State<BaseApp> {
// define all navigation tabs for user
static List<NavigationTabModel> _navigationTabs = [
NavigationTabModel(
title: 'Home',
icon: Icons.home,
url: '/home',
navigatorKey: GlobalKey<NavigatorState>(),
),
NavigationTabModel(
title: 'Search',
icon: Icons.search,
url: '/search',
navigatorKey: GlobalKey<NavigatorState>(),
),
NavigationTabModel(
title: 'Profile',
icon: Icons.person,
url: '/profile',
navigatorKey: GlobalKey<NavigatorState>(),
),
];
// route generator used to build all material page routes
RouteGenerator _routeGenerator = RouteGenerator();
// set the current tab to the home page
int _currentIndex = 0;
void _select(int index) {
if (index == _currentIndex) {
// case 1 - if user presses on currently selected tab
// pop to first route - i.e. ensure no routes are over laid on top of the current route
_navigationTabs[_currentIndex]
.navigatorKey
.currentState
.popUntil((route) {
return route.isFirst;
});
} else {
// case 2 - user selects any other tab
// rebuild application state with the newly selected navigation tab
setState(() {
_currentIndex = index;
});
}
}
/// generate a list of navigators that will have their state persisted in an
/// indexed stack.
List<Widget> _getPersistantStack() {
return _navigationTabs.map((tab) {
return WillPopScope(
onWillPop: () async {
return !await tab.navigatorKey.currentState.maybePop();
},
child: Navigator(
key: tab.navigatorKey,
initialRoute: tab.url,
onGenerateRoute: _routeGenerator.generateRoute,
),
);
}).toList();
}
@override
Widget build(BuildContext context) {
/// ********************* HOLD POINT *********************
/// MaterialApp contains our top-level Navigator. Top level navigator is
/// required to enable navigation via urls in flutter web. Likely that this
/// section requires refractoring in some way to enable url updates from the
/// nested navigators and hyperlinking from web browsers to specific pages
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
body: SafeArea(
child: IndexedStack(
children: _getPersistantStack(),
index: _currentIndex,
),
),
bottomNavigationBar: BottomNavigationBar(
items: _navigationTabs.map((tab) {
return BottomNavigationBarItem(
label: tab.title,
icon: Icon(tab.icon),
);
}).toList(),
onTap: (int index) {
_select(index);
},
currentIndex: _currentIndex,
type: BottomNavigationBarType.fixed,
// hide titles on navigation bar
showSelectedLabels: false,
showUnselectedLabels: false,
),
),
);
}
}
class NavigationTabModel {
final String title;
final IconData icon;
final String url;
final GlobalKey<NavigatorState> navigatorKey;
NavigationTabModel({
this.title,
this.icon,
this.url,
this.navigatorKey,
});
}
class RouteGenerator {
Route<dynamic> generateRoute(RouteSettings settings) {
// Widget builder (function that returns a widget) to construct the route page
WidgetBuilder builder;
// build different route (page) based on the route passed to the navigator
switch (settings.name) {
case '/home':
builder = (BuildContext context) {
return SamplePage(name: 'home');
};
break;
case '/search':
builder = (BuildContext context) {
return SamplePage(name: 'search');
};
break;
case '/profile':
builder = (BuildContext context) {
return SamplePage(name: 'profile');
};
break;
case '/':
builder = null;
break;
default:
// If there is no such named route in the switch statement
builder = (BuildContext context) {
return SamplePage();
};
}
// prevent page being added to default '/' route
if (builder == null) {
return null;
}
return MaterialPageRoute(
builder: builder,
settings: settings,
);
}
}
class SamplePage extends StatelessWidget {
final String name;
SamplePage({
this.name,
});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('$name'),
),
body: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: [
RaisedButton(
child: Text('push new route'),
onPressed: () {
Navigator.of(context).pushNamed('/$name');
},
),
SizedBox(
height: 16,
),
Expanded(
child: ListView.builder(
itemCount: 100,
itemBuilder: (context, index) {
return Card(
child: Text(
index.toString(),
),
);
},
),
),
],
),
),
);
}
}

然而，我不知道如何更新这个应用程序来实现第3点和第4点。有人知道如何做到这一点吗？

虽然Navigator 2.0一开始有点吓人，但当您(主要)针对web应用程序时，它是非常值得的，因为您有很多从深度链接恢复状态的选项。

在@Lulupointu已经链接到的官方介绍中，有一个例子正是你想要的(但有点隐藏在文章的底部)。

在这个要点中，是一个为不同选项卡使用不同Navigator Stack的工作示例，为了完整起见，我在下面发布了这个示例。它适用于我的频道测试版，1.23.0.18.1.pre

import 'package:flutter/material.dart';
void main() {
runApp(NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
@override
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
notifyListeners();
}
Book get selectedBook => _selectedBook;
set selectedBook(Book book) {
_selectedBook = book;
notifyListeners();
}
int getSelectedBookById() {
if (!books.contains(_selectedBook)) return 0;
return books.indexOf(_selectedBook);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location);
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return null;
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
@override
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (path is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (path is BooksDetailsPath) {
appState.selectedIndex = 0;
appState.setSelectedBookById(path.id);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
AppShell({
@required this.appState,
});
@override
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
InnerRouterDelegate _routerDelegate;
ChildBackButtonDispatcher _backButtonDispatcher;
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher
.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook),
),
] else
FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
FadeAnimationPage({Key key, this.child}) : super(key: key);
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
BooksListScreen({
@required this.books,
@required this.onTapped,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
@required this.book,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
if (book != null) ...[
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}

如果你想让主页导航按钮链接到主页而不保持状态，那么你必须将set selectedIndex替换为：

set selectedIndex(int idx) {
_selectedIndex = idx;
if (_selectedIndex == 1) {
// Remove this line if you want to keep the selected book when navigating
// between "settings" and "home" which book was selected when Settings is
// tapped.
selectedBook = null;
}
notifyListeners();
}

在编写自己的RouteInformationParser时，您可能需要了解如何提取查询参数：使用Dart 解析URI以提取查询参数

以下是您可能想了解Navigator 2.0的另一个示例：https://github.com/flutter/flutter/pull/63424

自2020年9月30日以来，flutter推出了Navigator 2.0。

您可以查看完整教程的链接。跳过有关Navigator 1.0的部分，转到Navigator 2.0。

基本上，两个主要的小部件是RouteInformationParser和RouterDelegate。

我强烈建议阅读这篇文章以及许多其他关于路由的信息。

也就是说，这是他们描述的代码，你可以在网上尝试，看看它是否达到了你的第3点和第4点。

import 'package:flutter/material.dart';
void main() {
runApp(BooksApp());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class BooksApp extends StatefulWidget {
@override
State<StatefulWidget> createState() => _BooksAppState();
}
class _BooksAppState extends State<BooksApp> {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location);
// Handle '/'
if (uri.pathSegments.length == 0) {
return BookRoutePath.home();
}
// Handle '/book/:id'
if (uri.pathSegments.length == 2) {
if (uri.pathSegments[0] != 'book') return BookRoutePath.unknown();
var remaining = uri.pathSegments[1];
var id = int.tryParse(remaining);
if (id == null) return BookRoutePath.unknown();
return BookRoutePath.details(id);
}
// Handle unknown routes
return BookRoutePath.unknown();
}
@override
RouteInformation restoreRouteInformation(BookRoutePath path) {
if (path.isUnknown) {
return RouteInformation(location: '/404');
}
if (path.isHomePage) {
return RouteInformation(location: '/');
}
if (path.isDetailsPage) {
return RouteInformation(location: '/book/${path.id}');
}
return null;
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey;
Book _selectedBook;
bool show404 = false;
List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>();
BookRoutePath get currentConfiguration {
if (show404) {
return BookRoutePath.unknown();
}
return _selectedBook == null
? BookRoutePath.home()
: BookRoutePath.details(books.indexOf(_selectedBook));
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
key: ValueKey('BooksListPage'),
child: BooksListScreen(
books: books,
onTapped: _handleBookTapped,
),
),
if (show404)
MaterialPage(key: ValueKey('UnknownPage'), child: UnknownScreen())
else if (_selectedBook != null)
BookDetailsPage(book: _selectedBook)
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
// Update the list of pages by setting _selectedBook to null
_selectedBook = null;
show404 = false;
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path.isUnknown) {
_selectedBook = null;
show404 = true;
return;
}
if (path.isDetailsPage) {
if (path.id < 0 || path.id > books.length - 1) {
show404 = true;
return;
}
_selectedBook = books[path.id];
} else {
_selectedBook = null;
}
show404 = false;
}
void _handleBookTapped(Book book) {
_selectedBook = book;
notifyListeners();
}
}
class BookDetailsPage extends Page {
final Book book;
BookDetailsPage({
this.book,
}) : super(key: ValueKey(book));
Route createRoute(BuildContext context) {
return MaterialPageRoute(
settings: this,
builder: (BuildContext context) {
return BookDetailsScreen(book: book);
},
);
}
}
class BookRoutePath {
final int id;
final bool isUnknown;
BookRoutePath.home()
: id = null,
isUnknown = false;
BookRoutePath.details(this.id) : isUnknown = false;
BookRoutePath.unknown()
: id = null,
isUnknown = true;
bool get isHomePage => id == null;
bool get isDetailsPage => id != null;
}
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
BooksListScreen({
@required this.books,
@required this.onTapped,
});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
@required this.book,
});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
if (book != null) ...[
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
],
),
),
);
}
}
class UnknownScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Center(
child: Text('404!'),
),
);
}
}

此要点的工作底部导航与flutter sdk>=2.12

import 'package:flutter/material.dart';
void main() {
runApp(NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
@override
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser = BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book? _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
notifyListeners();
}
Book? get selectedBook => _selectedBook;
set selectedBook(Book? book) {
_selectedBook = book;
notifyListeners();
}
int? getSelectedBookById() {
if (_selectedBook == null || !books.contains(_selectedBook)) return null;
return books.indexOf(_selectedBook!);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location ?? '');
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return RouteInformation();
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (path is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (path is BooksDetailsPath && path.id != null) {
appState.setSelectedBookById(path.id!);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int? id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
AppShell({
required this.appState,
});
@override
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
late InnerRouterDelegate _routerDelegate;
late ChildBackButtonDispatcher _backButtonDispatcher;
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context).backButtonDispatcher!.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook!),
),
] else
FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
FadeAnimationPage({required LocalKey key, required this.child}) : super(key: key);
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
BooksListScreen({
required this.books,
required this.onTapped,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
required this.book,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}

我已经四处寻找这个问题的答案太久了。我正在进行的一个项目已经进行了2周13次迭代，但我仍然对我看到/尝试过的许多解决方案都不满意，因为它们中的每一个都至少有一个主要的折衷方案，我最终艰难地学会了。我想我现在已经在这方面花了足够的时间，可以说flutter还没有适合这个用例(既不优雅也不简单，而且无论如何都不会破坏其他flutter功能)。他们"；支持"；网络，但目前，它们并没有为此进行优化，而且很难创建模仿网络行为的应用程序。然而，这并不令人惊讶，因为他们在Flutter 2022战略中基本上表明了这一点：

Flutter在2021年发布了第一个稳定的网络支持版本现在预测其最终成功还为时过早。然而，网络开发商市场巨大(1000多万)，Flutter提供了一些东西与传统的基于DOM的相比，这对受众来说是与众不同的框架。作为CanvasKit、WebGPU、AOM和具有GC的WebAssembly可用，Flutter处于独特的地位能够瞄准为新一代网络设计的网络应用程序。它的分层方法非常适合针对Canvas和WebGPU；Dart现在可以编译到高度优化的JavaScript，并将支持未来的WebAssembly；以及我们一贯的Flutter平易近人API与复杂的"不包含电池"网络形成了鲜明对比生态系统即使我们在不久的将来的角色是小众的，网络生态系统足够大，它们的利基市场就是我们的成长机会

然而，跨平台的功能可不是闹着玩的，因此我甚至花了这么多时间和精力试图找到一个解决方案，而使用我的网络背景，我只需要不到10分钟就可以完成这个问题。我相信很多其他人都是这样，所以下面是答案的更新和改进版本，它与最新版本的flutter和零安全配合使用，还使用内置的后退按钮，而不是其他答案使用的自定义按钮实现：

import 'package:flutter/material.dart';
void main() {
runApp(const NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
const NestedRouterDemo({Key? key}) : super(key: key);
@override
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
final BookRouterDelegate _routerDelegate = BookRouterDelegate();
final BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book? _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
// uncomment this line if you dont want to keep the selected book when navigating
// between "settings" and "home" although if your doing this you should only really need 1 nested navigator for the whole app
// if (_selectedIndex == 1) {
//   selectedBook = null;
// }
notifyListeners();
}
Book? get selectedBook => _selectedBook;
set selectedBook(Book? book) {
_selectedBook = book;
notifyListeners();
}
int getSelectedBookById() {
if (!books.contains(_selectedBook)) return 0;
return books.indexOf(_selectedBook!);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location!);
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1])!);
}
}
return BooksListPath();
}
}
@override
RouteInformation? restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return const RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return const RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return null;
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
@override
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath configuration) async {
if (configuration is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (configuration is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (configuration is BooksDetailsPath) {
appState.selectedIndex = 0;
appState.setSelectedBookById(configuration.id);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
const AppShell({
Key? key,
required this.appState,
}) : super(key: key);
@override
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
late InnerRouterDelegate _routerDelegate;
late ChildBackButtonDispatcher _backButtonDispatcher;
@override
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher!
.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
body: SizedBox(
height: double.infinity,
width: double.infinity,
child: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
),
bottomNavigationBar: BottomNavigationBar(
items: const [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: const ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook!),
),
] else
const FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
const FadeAnimationPage({required LocalKey key, required this.child})
: super(key: key);
@override
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
const BooksListScreen({
Key? key,
required this.books,
required this.onTapped,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Books'),
),
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
const BookDetailsScreen({
Key? key,
required this.book,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(book.title),
),
body: Center(
child: SizedBox(
width: 200,
child: ListTile(
title: Text(book.title),
subtitle: Text(book.author),
),
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
const SettingsScreen({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Settings'),
),
body: const Center(
child: Text('Settings screen'),
),
);
}
}

还有一些额外的东西值得一提：

  1. 上面的这个例子显示为中断页面转换&英雄动画(因此使用"FadeAnimationPage")。我已经为移动开发找到了Flutter Navigator 2.0：Nested navigators基础，它声称有一个解决方案，但我在这个例子中没有成功实现它
  2. 我只使用了这个例子，因为它是以前的答案，并且被打破了，但我认为这太过分了。我认为实现这样的东西最常见的用例是尝试为仍然可以使用路由的web创建持久导航。为此，整个应用程序只需要一个嵌套导航器。我还读到嵌套导航器也会对性能产生重大影响，因此我实际上建议不要使用超过1个导航器，除非您有非常具体的原因
  3. 最后，这个例子太复杂了，扑动团队知道这一点。他们甚至启动了Flutter用户体验研究(UXR)，试图解决这个问题，但如果我说实话，这方面的活动并没有我希望看到的那么多。这就是为什么我建议使用GoRouter这样的软件包。他们在这里有一个非常有文档的嵌套导航教程

相关内容

最新更新


热门标签：

javascript python java c# php android html jquery c++ css ios sql mysql arrays asp.net json python-3.x ruby-on-rails .net sql-server django objective-c excel regex ruby linux ajax iphone xml vba spring asp.net-mvc database wordpress string postgresql wpf windows xcode bash git oracle list vb.net multithreading eclipse algorithm macos powershell visual-studio image forms numpy scala function api selenium