Problem in Shared Preferenced in LoginScreen. Flut

help and explain to me in detail please how can I modify my code. I am beginner in Flutter and now I am doing tasks, the essence of which is the use of Shared Preferenced in the Login Screen and saving the user data in FireBase. When the user first entered the data, he entered the Home screen, but when the user exits the application and tries to log in again, it should be that he does not need to enter the password and login again.

Also, I knocked out such an error

    import 'package:flutter/material.dart';
import 'package:logining/home_screen/home_screen.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:shared_preferences/shared_preferences.dart';


class LoginScreen extends StatefulWidget {
  @override
  LoginScreenState createState() {
    return new LoginScreenState();
  }
}
enum LoginStatus{
  notSignIn,
  signIn,
}

class LoginScreenState extends State<LoginScreen> {
  LoginStatus _loginStatus = LoginStatus.notSignIn;
  String _email, _password;
  bool _obscureText = true;




  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  final FirebaseAuth _auth = FirebaseAuth.instance;
  final GoogleSignIn googleSignIn = GoogleSignIn();
  TextEditingController email = new TextEditingController();
  TextEditingController password = new TextEditingController();
  SharedPreferences sharedPreferences;


  Future<FirebaseUser> _signInGoogle() async{
    GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();
    GoogleSignInAuthentication gSa =await googleSignInAccount.authentication;

    FirebaseUser user = await _auth.signInWithGoogle(
      idToken: gSa.idToken,
      accessToken: gSa.accessToken
      );
      print('User Name : ${user.displayName}');
      return Navigator.push(context, MaterialPageRoute(builder: (context) => HomeScreen(user: user)));
  }

  safePref()async{
   SharedPreferences preferences = await SharedPreferences.getInstance();
   setState((){
     preferences.setString('email', _email);
     preferences.setString('password', _password);
     preferences.commit();
   }); 
  }
  var value;
  getPref()async{
    SharedPreferences preferences = await SharedPreferences.getInstance();
    setState(() {
      value = preferences.getInt('password');
      value = preferences.getInt('email');

      _loginStatus = value == 1 ? LoginStatus.signIn :LoginStatus.notSignIn;
    });
  }
  @override
  void initState(){
    super.initState();
    getPref();
  }

  @override
  Widget build(BuildContext context) {
    switch(_loginStatus){
      case LoginStatus.notSignIn:
        return Scaffold(
        appBar: AppBar(
          title: Text('Login'),
        ),
        resizeToAvoidBottomPadding: false,
        body: ListView(children: <Widget>[
          Container(
            child: Form(
              key: _formKey,
              autovalidate: true,
              child: Column(
                children: <Widget>[
                  SizedBox(
                    height: 50,
                  ),
                  Padding(
                    child: Image.asset(
                      'images/logo.png',
                      width: 100.0,
                      height: 100.0,
                    ),
                    padding: EdgeInsets.fromLTRB(50, 0, 50, 40),
                  ),
                  Padding(
                    padding: EdgeInsets.fromLTRB(25, 0, 50, 10),
                    child: TextFormField(
                      controller: email,
                      validator: (email) {
                        if (email.isEmpty) {
                          return 'Provide an Email';
                        }
                      },
                      style: TextStyle(
                        color: Color(0xFF01579B),
                        fontSize: 18.0,
                      ),
                      decoration: InputDecoration(
                          border: OutlineInputBorder(
                            borderRadius: BorderRadius.circular(30),
                          ),
                          hintText: 'Enter your Email',
                          labelText: "Email",
                          icon: Padding(
                            padding: EdgeInsets.only(top: 20.0),
                            child: Icon(Icons.email),
                          )),
                      onSaved: (email) => _email = email,
                    ),
                  ),
                  Padding(
                    padding: EdgeInsets.fromLTRB(25, 0, 50, 10),
                    child: TextFormField(
                      controller: password,
                      validator: (password) {
                        if (password.isEmpty) {
                          return 'Provide an password';
                        }
                      },
                      obscureText: _obscureText,
                      style: TextStyle(
                        color: Color(0xFF01579B),
                        fontSize: 18.0,
                      ),
                      decoration: InputDecoration(
                        border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(30),
                        ),
                        hintText: 'Enter your password',
                        labelText: "Password",
                        icon: Padding(
                          padding: EdgeInsets.only(top: 15.0),
                          child: Icon(Icons.lock),
                        ),
                        suffixIcon: GestureDetector(
                          onTap: () {
                            setState(() {
                              _obscureText = !_obscureText;
                            });
                          },
                          child: Icon(
                            _obscureText
                                ? Icons.visibility
                                : Icons.visibility_off,
                            semanticLabel: _obscureText
                                ? 'show password'
                                : 'hide password',
                          ),
                        ),
                      ),
                      onSaved: (password) => _password = password,
                    ),
                  ),
                  Row(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        Padding(
                          padding: EdgeInsets.symmetric(horizontal: 10),
                          child: RaisedButton(
                            color: Color(0xFFD50000),
                            textColor: Color(0xFFFFFFFF),
                            child: Text('Login with Google'),
                            onPressed:(){ _signInGoogle().then((FirebaseUser user){
                              print(user);
                            }).catchError((onError){
                              print(onError);
                            });

                            }
                          ),

                        ),
                        Padding(
                          padding: EdgeInsets.symmetric(horizontal: 10),
                          child: RaisedButton(
                            color: Color(0xFF448AFF),
                            textColor: Color(0xFFFFFFFF),
                            child: Text('Login'),
                            onPressed: signIn,
                          ),
                        ),
                  ]),
                      Padding(
                          padding:
                              EdgeInsets.symmetric(horizontal: 10, vertical: 5),
                          child: FlatButton(
                            textColor: Color(0xFF448AFF),
                            child: Text('Forgot Password'),
                            onPressed: () {
                              print('onPressed');
                            },
                          ),
                        ),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.fromLTRB(50, 70, 0, 10),
                        child: Text(
                          'Still do not have an account ',
                          style: TextStyle(color: Color(0xFF9E9E9E)),
                        ),
                      ),
                      Padding(
                        padding: EdgeInsets.fromLTRB(0, 70, 30, 10),
                        child: FlatButton(
                          textColor: Color(0xFF448AFF),
                          child: Text('registration'),
                          onPressed: () {
                            Navigator.of(context).pushNamedAndRemoveUntil(
                                '/registration', (Route<dynamic> route) => false);
                          },
                        ),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ),
        ]),
      );
        break;
      case LoginStatus.signIn:
        return HomeScreen();
        break;
    }

  }
Future<void> signIn() async {
    final formState = _formKey.currentState;
    if(formState.validate()) {

      setState(() {
       _loginStatus = LoginStatus.signIn;
       formState.save();
      });
      try {
        FirebaseUser user = await FirebaseAuth.instance.signInWithEmailAndPassword(email: _email, password: _password); 
      }catch(e){
        print(e.message);
      }
    }
}
}

回答1:

after looking at your code i think i see where the problem is. The way i have understood your code is that the method 'safePref' is called to save password and email to shared preferences. Also, i hope its true that the method to get from shared preferences is 'getPref'. The error comes in that the value stored is a String

preferences.setString('email', _email);
preferences.setString('password', _password);

and the value read from storage is expected to be an Integer

value = preferences.getInt('password');
value = preferences.getInt('email');

You should change the last two to be

value = preferences.getString('password');
value = preferences.getString('email');

since the value stored is a String. To compare the Strings against integers you can change the statement

_loginStatus = value == 1 ? LoginStatus.signIn :LoginStatus.notSignIn;

to be

_loginStatus = int.parse(value) == 1 ? LoginStatus.signIn :LoginStatus.notSignIn;

My solution should solve the String problem but i think it will always return a false unless the Users Password is '1'. Hope this helps. Thanks.

回答2:

You have as String value and try to read as int value here's the problem . You should first read as String your email and password and then parse them to int.

 var value;
 getPref()async{

SharedPreferences preferences = await SharedPreferences.getInstance();

setState(() {
  value = preferences.getString('password');
  value = preferences.getString('email');
  _loginStatus = int.parse(value) == 1 ? LoginStatus.signIn :LoginStatus.notSignIn;
});
}