我正在Flutter中使用Firebase Google身份验证创建应用。我能够登录到该应用程序,但是当我关闭该应用程序时,身份验证被删除,这要求我再次登录。
这是我的登录屏幕,“使用Google登录”按钮将触发_signInButton()中的onPressed()。
import 'package:flutter/material.dart';
import 'package:auth_screen/sign_in.dart';
import 'package:auth_screen/homepage.dart';
class LoginPage extends StatefulWidget {
@override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
color: Colors.white,
child: Center(
child: Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Image(image: AssetImage("assets/thelogo.jpg"), height: 200.0),
SizedBox(height: 25),
_signInButton(),
],
),
),
),
);
}
Widget _signInButton() {
return OutlineButton(
splashColor: Colors.grey,
onPressed: () {
signInWithGoogle().whenComplete(() {
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) {
return MyHomePage();
},
),
);
});
},
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(40)),
highlightElevation: 0,
borderSide: BorderSide(color: Colors.grey),
child: Padding(
padding: const EdgeInsets.fromLTRB(0, 10, 0, 10),
child: Row(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Image(image: AssetImage("assets/google_logo.png"), height: 35.0),
Padding(
padding: const EdgeInsets.only(left: 10),
child: Text(
'Sign in with Google',
style: TextStyle(
fontSize: 20,
color: Colors.grey,
),
),
)
],
),
),
);
}
}
这是所有Google和Firebase进行身份验证的页面。
import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
final FirebaseAuth _auth = FirebaseAuth.instance;
final GoogleSignIn googleSignIn = GoogleSignIn();
String name;
String email;
String imageUrl;
Future<String> signInWithGoogle() async {
final GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();
final GoogleSignInAuthentication googleSignInAuthentication = await googleSignInAccount.authentication;
final AuthCredential credential = GoogleAuthProvider.getCredential(
accessToken: googleSignInAuthentication.accessToken,
idToken: googleSignInAuthentication.idToken,
);
final AuthResult authResult = await _auth.signInWithCredential(credential);
final FirebaseUser user = authResult.user;
imageUrl = user.photoUrl;
assert(!user.isAnonymous);
assert(await user.getIdToken() != null);
final FirebaseUser currentUser = await _auth.currentUser();
assert(user.uid == currentUser.uid);
//return 'signInWithGoogle succeeded: $user';
}
void signOutGoogle() async{
await googleSignIn.signOut();
theID = '';
print("User Sign Out");
}
我听说Firebase默认会保留用户身份验证,但是在我的程序中不会发生。有什么方法可以使用户身份验证持续到我按下注销按钮?如果您有任何想法请告诉我。
答案 0 :(得分:0)
Firebase确实存储持久性身份验证,您只需要调用它即可!
有两种方法可以解决此问题:
Future<void> _handleStartScreen() async {
Auth _auth = Auth();
if (await _auth.isLoggedIn()) {
Navigator.popAndPushNamed(context, HomeScreen.id);
} else {
Navigator.popAndPushNamed(context, WelcomeScreen.id);
}
}
您可以从启动屏幕的初始状态调用它。
2. 使用Shared_pref :-这是最常用的方法。在这种情况下,您可以使用程序包shared_preferences(https://pub.dev/packages/shared_preferences#-readme-tab-将身份验证状态存储在应用内本地,您可以从给定的链接中查看如何使用它)
因此,每当用户登录时,都用logged_in = true
将布尔值存储在其中,并且每当应用程序启动时,您都将从初始屏幕中调用shared_preferences的实例。
您可以在登出后切换logging_in var。