在Future builder内部使用本地身份验证将在身份验证后调用本地身份验证无限次

Question

在用户使用应用程序之前，我尝试使用本地身份验证对用户进行身份验证。但问题是，我必须使用Future Builder检查用户数据，才能进入主屏幕或登录屏幕。因此，我必须在Future Builder中使用本地身份验证来验证用户身份。但这会导致在我到达主屏幕后调用指纹身份验证无数次。所以我们不能摆脱本地身份验证。请帮帮忙，告诉我有没有别的办法。提前感谢:)

 class MyApp extends StatefulWidget {
      @override
      _MyAppState createState() => _MyAppState();
    }
    
    class _MyAppState extends State<MyApp> {
      final AuthMethods _authMethods = AuthMethods();
      final LocalAuthentication _localAuthentication = LocalAuthentication();
      bool _hasFingerPrintSupport = false;
      bool _authorizedOrNot = false;
      List<BiometricType> _availableBuimetricType = List<BiometricType>();
    
      @override
      void initState() {
        super.initState();
        _getBiometricsSupport();
        _getAvailableSupport();
      }
    
      Future<void> _getBiometricsSupport() async {
        bool hasFingerPrintSupport = false;
        try {
          hasFingerPrintSupport = await _localAuthentication.canCheckBiometrics;
        } catch (e) {
          print(e);
        }
        if (!mounted) return;
        setState(() {
          _hasFingerPrintSupport = hasFingerPrintSupport;
        });
      }
        Future<void> _getAvailableSupport() async {
    
        List<BiometricType> availableBuimetricType = List<BiometricType>();
        try {
          availableBuimetricType =
              await _localAuthentication.getAvailableBiometrics();
        } catch (e) {
          print(e);
        }
        if (!mounted) return;
        setState(() {
          _availableBuimetricType = availableBuimetricType;
        });
      }
    
      Future<void> _authenticateMe() async {
     
        bool authenticated = false;
        try {
          authenticated = await _localAuthentication.authenticateWithBiometrics(
            localizedReason: "Authenticate to use App", // message for dialog
            useErrorDialogs: true,// show error in dialog
            stickyAuth: false,// native process
          );
        } catch (e) {
          print(e);
        }
        if (!mounted) return;
        setState(() {
          _authorizedOrNot = authenticated ? true : false;
        });
      }
    
      @override
      Widget build(BuildContext context) {
        final themeNotifier = Provider.of<ThemeNotifier>(context);
      _authenticateMe();
        return MultiProvider(
          providers: [
            ChangeNotifierProvider(
              create: (_) => ThemeNotifier(darkTheme),
            ),
            ChangeNotifierProvider(create: (_) => ImageUploadProvider()),
            ChangeNotifierProvider(
              create: (_) => VideoUploadProvider(),
            ),
            ChangeNotifierProvider(create: (_) => UserProvider()),
          ],
          child: MaterialApp(
            title: "App",
            debugShowCheckedModeBanner: false,
            initialRoute: '/',
            routes: {
              '/search_screen': (context) => SearchScreen(),
              '/setting_page': (context) => settingPage(),
            },
            theme: themeNotifier.getTheme(),
            home: FutureBuilder(
              future: _authMethods.getCurrentUser(),
              builder: (context, AsyncSnapshot<User> snapshot) {
                   
                if (snapshot.hasData ) {
                   return _authorizedOrNot==true ? HomeScreen() : Container(); 
                } else {
                  return LoginScreen();
                }
              },
            ),
          ),
        );
      }
    }

Answer 1

在这种情况下，在构建开始时调用_authenticateMe(); ()。

_authenticateMe();在setState内部导致build()再次触发并调用_authenticateMe();，从而进行重建，从而进行重建。

附注:我会将FutureBuilder向上移动，直到超过MaterialApp为止，这可能会导致使用热重新加载时出现问题。

Answer 2

好吧，我想出了一种方法，在初始化状态下调用身份验证函数，然后在返回Future builder之前检查isauthorizedorNot。以下是代码：

class _MyAppState extends State<MyApp> {
final LocalAuthentication _localAuthentication = LocalAuthentication();
    final AuthMethods _authMethods = AuthMethods();
  bool _authorizedOrNot ;

  Future<void> _authenticateMe() async {
    bool authenticated = false;
    try {
      authenticated = await _localAuthentication.authenticateWithBiometrics(
        localizedReason: "Authenticate to use app", 
        useErrorDialogs: true,

        stickyAuth: false, 
      );
    } catch (e) {
      print(e);
    }
    if (!mounted) return;
    setState(() {
      _authorizedOrNot = authenticated ? true : false;
    });
  }

  @override
  void initState() {
   
    super.initState();
    _authenticateMe();
  }
  @override
  Widget build(BuildContext context) {
 
    final themeNotifier = Provider.of<ThemeNotifier>(context);
    
    return MultiProvider(
      providers: [
        ChangeNotifierProvider(
          create: (_) => ThemeNotifier(darkTheme),
        ),
        ChangeNotifierProvider(create: (_) => ImageUploadProvider()),
        ChangeNotifierProvider(
          create: (_) => VideoUploadProvider(),
        ),
        ChangeNotifierProvider(create: (_) => UserProvider()),
      ],
      child: MaterialApp(
        title: "App",
        debugShowCheckedModeBanner: false,
        initialRoute: '/',
        routes: {
          '/search_screen': (context) => SearchScreen(),
          '/setting_page': (context) => settingPage(),
        },
        theme: themeNotifier.getTheme(),
        home: _authorizedOrNot==true ?  FutureBuilder(
          future: _authMethods.getCurrentUser(),
          builder: (context, AsyncSnapshot<User> snapshot) {
 
            if (snapshot.hasData) {
              return HomeScreen();
             
            } else {
              return LoginScreen();
            
            }
          },
        )  : ( Container(child: Center(child: CircularProgressIndicator()),)
      ),)
    );
  }
}