Flutter 安全存储更改路线

Question

I have successfully implemented the flutter_secure_storage in my flutter project, when the user writes his email and password, it get's stored, but here is the thing I don't understand. How should I setup screen routes depending if the user has already logged in or not. If it is the same user, so the username and pass are stored in the secure_storage, I want him to go directly to HomeScreen() , but if there is a new user that needs to log in, so there is no data in the secure_storage, then I want him sent to LoginScreen() . I have done this so far:

import 'dart:async';
import 'package:flutter/material.dart';
import 'login_screen.dart';
import 'home_screen.dart';
import 'components/alarm_buttons.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

class WelcomeScreen extends StatefulWidget {
  static const String id = 'welcome_screen';
  @override
  _WelcomeScreenState createState() => _WelcomeScreenState();
}

class _WelcomeScreenState extends State<WelcomeScreen> {
  void readData() async {
    final storage = FlutterSecureStorage();
    String myPassword = await storage.read(key: "p");
    String myEmail = await storage.read(key: "e");
    print(myEmail);
    print(myPassword);
  }

  @override
  void initState() {
    final storage = FlutterSecureStorage();
    Timer(
        Duration(seconds: 2),
        () => Navigator.pushNamed(
              context,
              storage == null ? LoginScreen.id : HomePage.id,
            ));
    readData();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: Padding(
        padding: EdgeInsets.symmetric(horizontal: 24.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            AlarmButtons(
              buttonColour: Colors.grey,
              buttonText: 'Log In',
              buttonTextColour: Colors.white,
              onButtonPress: () {
                Navigator.pushNamed(context, LoginScreen.id);
              },
            ),
            AlarmButtons(
              buttonColour: Colors.white,
              buttonText: 'Sign up',
              buttonTextColour: Colors.grey,
              onButtonPress: () {
                Navigator.pushNamed(context, SignUpScreen.id);
              },
            ),
          ],
        ),
      ),
    );
  }
}

Now the problem starts when I want to return to the Welcome Screen (the starting page of my app shown above), naturally it triggers the initState again and I get back to the HomePage() again. How can I dispose of that, only triggering that initState when the app starts, so after automatic login I can return to the Welcome Screen without triggering it?

Thanks in advance!

Answer 1

You should initial start something like a SplashScreen (or WelcomeScreen in your case). There you can decide to which screen you want to navigate based on the saved data. Example:

class SplashScreen extends StatefulWidget {
  const SplashScreen({Key key}) : super(key: key);

  @override
  _SplashScreenState createState() => _SplashScreenState();
}

class _SplashScreenState extends State<SplashScreen> {
  @override
  void initState() {
    _startApp();
    super.initState();
  }

  Future<void> _startApp() async {
    final storage = FlutterSecureStorage();
    String myEmail = await storage.read(key: "e");
    if (myEmail == null) {
      // TODO Navigate to Login Screen
    } else {
      // TODO Navigate to Home Screen
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text("Splashscreen"),
      ),
    );
  }
}