颤动如何修复权限处理程序错误
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【中文标题】颤动如何修复权限处理程序错误【英文标题】：flutter how to fix permission handler error 【发布时间】：2022-01-15 04:44:21 【问题描述】：我不知道如何解决这个红色错误部分。 我从互联网上复制了这个然后我得到了这个错误。 请帮我解决这个问题。
这是我的完整代码。
import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:android_intent/android_intent.dart';
import 'package:geolocator/geolocator.dart';
class AskForPermission extends StatefulWidget
@override
_AskForPermissionState createState() => _AskForPermissionState();
class _AskForPermissionState extends State<AskForPermission>
final PermissionHandler permissionHandler = PermissionHandler();
Map<PermissionGroup, PermissionStatus>? permissions;
void initState()
super.initState();
requestLocationPermission();
_gpsService();
Future<bool> _requestPermission(PermissionGroup permission) async
final PermissionHandler _permissionHandler = PermissionHandler();
var result = await _permissionHandler.requestPermissions([permission]);
if (result[permission] == PermissionStatus.granted)
return true;
return false;
/*Checking if your App has been Given Permission*/
Future<bool> requestLocationPermission(Function? onPermissionDenied) async
var granted = await _requestPermission(PermissionGroup.location);
if (granted!=true)
requestLocationPermission();
debugPrint('requestContactsPermission $granted');
return granted;
/*Show dialog if GPS not enabled and open settings location*/
Future _checkGps() async
if (!(await Geolocator.isLocationServiceEnabled()))
if (Theme.of(context).platform == TargetPlatform.android)
showDialog(
context: context,
builder: (BuildContext context)
return AlertDialog(
title: Text("Can't get gurrent location"),
content:const Text('Please make sure you enable GPS and try again'),
actions: <Widget>[
FlatButton(child: Text('Ok'),
onPressed: ()
final AndroidIntent intent = AndroidIntent(
action: 'android.settings.LOCATION_SOURCE_SETTINGS');
intent.launch();
Navigator.of(context, rootNavigator: true).pop();
_gpsService();
)],
);
);
/*Check if gps service is enabled or not*/
Future _gpsService() async
if (!(await Geolocator.isLocationServiceEnabled()))
_checkGps();
return null;
else
return true;
@override
Widget build(BuildContext context)
return Scaffold(
appBar: AppBar(
title: Text('Ask for permisions'),
backgroundColor: Colors.red,
),
body: Center(
child: Column(
children: <Widget>[
Text("All Permission Granted"),
],
))
);
【问题讨论】：
这是 pub 权限处理程序中的包搜索 你在pubspec.yaml中添加了permission_handler吗？ @PoojaPatil 是的，我添加了，但实际上这段代码是旧版本的权限处理程序，我在 yaml 文件中添加了新版本的权限处理程序 【参考方案1】：安装权限处理程序包from here。然后在您的 .dart 文件中添加导入并在某处调用权限询问功能。例如。像这样的函数要求存储权限。
import 'package:permission_handler/permission_handler.dart';
Future<void> getStoragePermission() async
if (await Permission.manageExternalStorage.request().isGranted)
setState(() );
else if (await Permission.storage.request().isPermanentlyDenied)
await openAppSettings();
else if (await Permission.storage.request().isDenied)
setState(() );
【讨论】：
【参考方案2】：请参考以下代码
https://pub.dev/packages/permission_handler/install 权限处理程序：^5.0.1+1
import 'package:permission_handler/permission_handler.dart';
import 'package:google_fonts/google_fonts.dart';
class MyApp extends StatelessWidget
MyApp(Key key) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context)
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Color(0xfff00B074),
textTheme: const TextTheme(
bodyText1: TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xff464255)),
),
),
home: PermissionHandlerScreen(),
);
class PermissionHandlerScreen extends StatefulWidget
@override
_PermissionHandlerScreenState createState() =>
_PermissionHandlerScreenState();
class _PermissionHandlerScreenState extends State<PermissionHandlerScreen>
@override
void initState()
super.initState();
permissionServiceCall();
permissionServiceCall() async
await permissionServices().then(
(value)
if (value != null)
if (value[Permission.storage].isGranted &&
value[Permission.camera].isGranted &&
value[Permission.microphone].isGranted)
/* ========= New Screen Added ============= */
Navigator.pushReplacement(
context,
MaterialPageRoute(builder: (context) => SplashScreen()),
);
,
);
/*Permission services*/
Future<Map<Permission, PermissionStatus>> permissionServices() async
// You can request multiple permissions at once.
Map<Permission, PermissionStatus> statuses = await [
Permission.storage,
Permission.camera,
Permission.microphone,
//add more permission to request here.
].request();
if (statuses[Permission.storage].isPermanentlyDenied)
openAppSettings();
setState(() );
else
if (statuses[Permission.storage].isDenied)
permissionServiceCall();
if (statuses[Permission.microphone].isPermanentlyDenied)
openAppSettings();
setState(() );
else
if (statuses[Permission.microphone].isDenied)
permissionServiceCall();
if (statuses[Permission.camera].isPermanentlyDenied)
openAppSettings();
setState(() );
else
if (statuses[Permission.camera].isDenied)
permissionServiceCall();
/*Permission.camera: PermissionStatus.granted, Permission.storage: PermissionStatus.granted*/
return statuses;
@override
Widget build(BuildContext context)
permissionServiceCall();
return WillPopScope(
onWillPop: ()
SystemNavigator.pop();
,
child: Scaffold(
body: Container(
child: Center(
child: InkWell(
onTap: ()
permissionServiceCall();
,
child: Text("Click here to enable Enable Permission Screen")),
),
),
),
);
class SplashScreen extends StatelessWidget
const SplashScreen(Key key) : super(key: key);
@override
Widget build(BuildContext context)
return WillPopScope(
onWillPop: ()
SystemNavigator.pop();
,
child: Scaffold(
body: Center(
child: Text(
"Splash Screen",
),
),
),
);
【讨论】：
【参考方案3】：在您的 pubspec.yaml 文件中添加 permission_handler 依赖项。
试试flutter pub get 命令。如果已经完成，请参考此链接了解permission handler package。
【讨论】：
【参考方案4】：我遇到了同样的问题 - 在我升级到 ^8.3.0 后，与 permission_handler ^8.0.0+2 一起工作的代码不再工作 - 代码无法编译，权限和其他不能编译的类“找到”了（我使用 VS Code）
我通过清理 pub 缓存修复了它：
flutter pub cache clean
然后再次获取依赖项：
flutter pub get
PS：为了升级到 8.3.0，我在 build.gradle 文件中设置了 targetSdkVersion 和 compileSdkVersion 为 31
【讨论】：
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