Android studio 如何在颤振中基于sharedPrefs值设置动态初始路径?
目前,我正在处理路由问题,我想根据SharedReferences值在我的应用程序中设置initialRoute 我对MaterialAppWidget使用Statedulwidget,并在从SharedPref获取数据后使用setState()方法。但是,每次我都会看到相同的屏幕Android studio 如何在颤振中基于sharedPrefs值设置动态初始路径?,android-studio,flutter,routes,sharedpreferences,flutter-layout,Android Studio,Flutter,Routes,Sharedpreferences,Flutter Layout,目前,我正在处理路由问题,我想根据SharedReferences值在我的应用程序中设置initialRoute 我对MaterialAppWidget使用Statedulwidget,并在从SharedPref获取数据后使用setState()方法。但是,每次我都会看到相同的屏幕 class MyApp extends StatefulWidget { @override _MyAppState createState() => _MyAppState(); } class _
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
int initScreen = 0;
initPrefs() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
initScreen = prefs.getInt("initScreen");
print("initScreen ${initScreen}");
setState(() {});
}
@override
void initState() {
super.initState();
initPrefs();
}
@override
Widget build(BuildContext context) {
print("initScreen2 ${initScreen}");
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Flutter Authentication',
theme: ThemeData(
primarySwatch: Colors.blue,
),
initialRoute: initScreen == 0 || initScreen == null
? MediatorPage.routeName
: PopUntilPage.routeName,
routes: {
CloudGroupCreate.routeName: (context) => CloudGroupCreate(),
CloudDashboard.routeName: (context) => CloudDashboard(),
PopUntilPage.routeName: (context) => PopUntilPage(),
ProviderWithFutureBuilderApp.routeName: (context) =>
ProviderWithFutureBuilderApp(),
MediatorPage.routeName: (context) => MediatorPage(),
},
);
}
}
类MyApp扩展StatefulWidget{
@凌驾
_MyAppState createState()=>\u MyAppState();
}
类MyAppState扩展了状态{
int initScreen=0;
initPrefs()异步{
SharedReferences prefs=等待SharedReferences.getInstance();
initScreen=prefs.getInt(“initScreen”);
打印(“initScreen${initScreen}”);
setState((){});
}
@凌驾
void initState(){
super.initState();
initPrefs();
}
@凌驾
小部件构建(构建上下文){
打印(“initScreen2${initScreen}”);
返回材料PP(
debugShowCheckedModeBanner:false,
标题:“颤振认证”,
主题:主题数据(
主样本:颜色。蓝色,
),
initialRoute:initScreen==0 | | initScreen==null
?第页:路由名称
:poputilpage.routeName,
路线:{
CloudGroupCreate.routeName:(上下文)=>CloudGroupCreate(),
CloudDashboard.routeName:(上下文)=>CloudDashboard(),
PoputilPage.routeName:(上下文)=>PoputilPage(),
ProviderWithFutureBuilderApp.routeName:(上下文)=>
具有FutureBuilderApp()的Provider,
MediatorPage.routeName:(上下文)=>MediatorPage(),
},
);
}
}
我不想使用直接小部件使用home property应用程序。我只想导航通过唯一和唯一使用命名的路线
有人能建议如何正确地做这件事吗
谢谢。您需要在
main()
中初始化SharedReferences
,并使用WidgetsFlutterBinding。确保重新初始化
您可以复制粘贴运行下面的完整代码
在演示中,我将initScreen设置为12
代码片段
int initScreen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
await prefs.setInt("initScreen",12);
initScreen = await prefs.getInt("initScreen");
print('initScreen ${initScreen}');
runApp(MyApp());
}
...
initialRoute: initScreen == 0 || initScreen == null
? "/"
: "first",
routes: {
'/': (context) => MyHomePage(title: "demo",),
"first": (context) => FirstPage(),
},
int初始化屏幕;
Future main()异步{
WidgetsFlutterBinding.ensureInitialized();
SharedReferences prefs=等待SharedReferences.getInstance();
等待prefs.setInt(“初始化屏幕”,12);
initScreen=await prefs.getInt(“initScreen”);
打印('initScreen${initScreen}');
runApp(MyApp());
}
...
initialRoute:initScreen==0 | | initScreen==null
? "/"
:“第一”,
路线:{
“/”:(上下文)=>MyHomePage(标题:“演示”),
“first”:(上下文)=>FirstPage(),
},
工作演示
完整代码
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
//void main() => runApp(MyApp());
int initScreen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
await prefs.setInt("initScreen",12);
initScreen = await prefs.getInt("initScreen");
print('initScreen ${initScreen}');
runApp(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(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
initialRoute: initScreen == 0 || initScreen == null
? "/"
: "first",
routes: {
'/': (context) => MyHomePage(title: "demo",),
"first": (context) => FirstPage(),
},
//home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
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: Column(
// Column is also a layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class FirstPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Text("First");
}
}
导入“包装:颤振/材料.省道”;
导入“package:shared_preferences/shared_preferences.dart”;
//void main()=>runApp(MyApp());
int初始化屏幕;
Future main()异步{
WidgetsFlutterBinding.ensureInitialized();
SharedReferences prefs=等待SharedReferences.getInstance();
等待prefs.setInt(“初始化屏幕”,12);
initScreen=await prefs.getInt(“initScreen”);
打印('initScreen${initScreen}');
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
//这是应用程序的主题。
//
//尝试使用“flutter run”运行应用程序。您将看到
//应用程序有一个蓝色工具栏。然后,在不退出应用程序的情况下,重试
//将下面的primarySwatch更改为Colors.green,然后调用
//“热重新加载”(在运行“颤振运行”的控制台中按“r”,
//或者只需将更改保存到颤振IDE中的“热重新加载”。
//请注意,计数器没有重置回零;应用程序
//未重新启动。
主样本:颜色。蓝色,
),
initialRoute:initScreen==0 | | initScreen==null
? "/"
:“第一”,
路线:{
“/”:(上下文)=>MyHomePage(标题:“演示”),
“first”:(上下文)=>FirstPage(),
},
//主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
//此小部件是应用程序的主页。它是有状态的,表示
//它有一个状态对象(定义如下),其中包含影响
//看起来怎么样。
//此类是状态的配置。它保存值(在此
//案例名称)由家长(在本例中为应用程序小部件)提供,以及
//由State的build方法使用。小部件子类中的字段包括
//始终标记为“最终”。
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
int _计数器=0;
void _incrementCounter(){
设置状态(){
//这个对setState的调用告诉颤振框架,某些东西
//已在此状态下更改,这将导致它重新运行下面的生成方法
//以便显示能够反映更新的值。如果我们更改
//_计数器,而不调用setState(),则生成方法将不可用
//再打一次电话,似乎什么也没发生。
_计数器++;
});
}
@凌驾
小部件构建(构建上下文){
//每次调用setState时都会重新运行此方法,例如,按done
//通过上面的_incrementCounter方法。
//
//对颤振框架进行了优化,以制定重新运行的构建方法
//快速,这样你就可以重建任何需要更新的东西
//而不是必须单独更改小部件的实例。
返回脚手架(
appBar:appBar(
//在这里,我们从MyHomePage对象中获取由创建的值
//使用App.build方法,并使用它设置appbar标题。
标题:文本(widget.title),
),
正文:中(
return _isLoadComplete? MaterialApp() : Container();
return MaterialApp(
key: UniqueKey(),
//etc