Flutter 如何使用riverpod在颤振中导航到另一个屏幕时保持应用程序的状态
大家好 我刚开始使用Riverpod,我有一个计数器应用程序,当点击FAB按钮时,计数器会增加1。这在使用Riverpod ChangeNotifierProvider时效果很好。 我目前遇到的问题是,当我单击另一个按钮将用户带到第二个屏幕时,计数器的状态将保留在第二个屏幕中 下面是我的代码 主飞镖Flutter 如何使用riverpod在颤振中导航到另一个屏幕时保持应用程序的状态,flutter,dart,provider,riverpod,Flutter,Dart,Provider,Riverpod,大家好 我刚开始使用Riverpod,我有一个计数器应用程序,当点击FAB按钮时,计数器会增加1。这在使用Riverpod ChangeNotifierProvider时效果很好。 我目前遇到的问题是,当我单击另一个按钮将用户带到第二个屏幕时,计数器的状态将保留在第二个屏幕中 下面是我的代码 主飞镖 import 'package:flutter/material.dart'; import 'package:flutter_riverpod/flutter_riverpod.dart'; im
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:flutter_riverpod_app/counter.dart';
import 'package:flutter_riverpod_app/second_screen.dart';
final counterProvider = ChangeNotifierProvider<Counter>((ref) => Counter());
void main() {
runApp(ProviderScope(
child: MyApp(),
));
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Consumer(builder: (context, watch, _) {
final count = watch(counterProvider);
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'${count.count}',
style: Theme.of(context).textTheme.headline4,
),
FlatButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (BuildContext context) => SecondScreen()));
},
child: Text('Go to second screen'))
],
);
}),
),
floatingActionButton: FloatingActionButton(
onPressed: () => context.read(counterProvider).updateCount(),
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
我真的不知道如何在第二个屏幕上获取计数器的状态,如果它是提供程序包,我只需在第二个屏幕上使用
Provider.of(context,listen:false)。计数器将显示计数器。问题是您创建了两次提供程序。您只需要创建一次并全局访问它
删除final counterProvider=ChangeNotifierProvider((ref)=>Counter())代码>从第二个屏幕导入,而从第一个屏幕导入反提供程序,它将按照您的预期运行
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:flutter_riverpod_app/counter.dart';
final counterProvider = ChangeNotifierProvider<Counter>((ref) => Counter());
class SecondScreen extends ConsumerWidget {
@override
Widget build(BuildContext context, watch) {
final counter = watch(counterProvider);
return Scaffold(
appBar: AppBar(
title: Text('Second Screen'),
),
body: Center(
child: Text('${counter.count}', style: TextStyle(fontSize: 30,),),
),
);
}
}
import 'package:flutter/foundation.dart';
class Counter extends ChangeNotifier {
int count = 0;
updateCount() {
count++;
notifyListeners();
}
}