Flutter google 登录 保持登录状态

Posted 2023-02-23

【中文标题】Flutter google 登录 保持登录状态

【英文标题】：Flutter google sign in stay logged in

【发布时间】：2019-06-10 08:24:54

【问题描述】：

我已经实现了 firebase auth google 登录，但是我如何在应用程序关闭后保持登录状态，我什至输入了这一行 await _auth.currentUser() 但仍然无法正常工作。下面是我的登录代码。

LoginPage.dart （旧）

import 'package:flutter/material.dart';

import 'package:firebase_auth/firebase_auth.dart';

//Google provider
import 'package:google_sign_in/google_sign_in.dart';
import 'package:flutter_facebook_login/flutter_facebook_login.dart';
import 'package:flutter_auth_buttons/flutter_auth_buttons.dart';

final FirebaseAuth _auth = FirebaseAuth.instance;
final GoogleSignIn _googleSignIn = new GoogleSignIn();

class LoginPage extends StatefulWidget 
    @override
    _LoginPageState createState() => _LoginPageState();


class _LoginPageState extends State<LoginPage> 
String _email;
String _password;
GoogleSignInAccount _currentUser;

@override
void initState() 
  super.initState();
  _googleSignIn.onCurrentUserChanged.listen((GoogleSignInAccount account) 

  setState(() 
    _currentUser = account;
  );
  if (_currentUser != null) 
    //_handleGetContact();
  
);
_googleSignIn.signInSilently();


//google sign in
GoogleSignIn googleAuth = new GoogleSignIn();

//Facebook sign in
FacebookLogin fbLogin = new FacebookLogin();

Future<FirebaseUser> _testSignInWithGoogle() async 
final GoogleSignInAccount googleUser = await _googleSignIn.signIn();
final GoogleSignInAuthentication googleAuth =
    await googleUser.authentication;
final AuthCredential credential = GoogleAuthProvider.getCredential(
  accessToken: googleAuth.accessToken,
  idToken: googleAuth.idToken,
);
final FirebaseUser user = await _auth.signInWithCredential(credential);
assert(user.email != null);
assert(user.displayName != null);
assert(!user.isAnonymous);
assert(await user.getIdToken() != null);

final FirebaseUser currentUser = await _auth.currentUser();
assert(user.uid == currentUser.uid);

print('Signed in as $user.displayName');
Navigator.of(context).pushReplacementNamed('/homepage');

return await _auth.currentUser();


void _facebookLogin() async 
var facebookLogin = FacebookLogin();
var facebookLoginResult =
    await facebookLogin.logInWithReadPermissions(['email', 
'public_profile']);

 switch (facebookLoginResult.status) 
  case FacebookLoginStatus.error:
    print("Error");
    onLoginStatusChanged(false);
    break;
  case FacebookLoginStatus.cancelledByUser:
    print("CancelledByUser");
    onLoginStatusChanged(false);
    break;
  case FacebookLoginStatus.loggedIn:
    print("LoggedIn");
    onLoginStatusChanged(true);

    FacebookAccessToken myToken = facebookLoginResult.accessToken;
    AuthCredential credential= 
FacebookAuthProvider.getCredential(accessToken: myToken.token);
    try 
      final FirebaseUser user = await 
FirebaseAuth.instance.signInWithCredential(credential);

      //Navigator.pushReplacement(context, MaterialPageRoute(builder: 
(context) => DiscoverPage()));
      print('Signed in as $user.displayName');
      Navigator.of(context).pushReplacementNamed('/homepage');
     catch (e) 
      debugPrint("Facebook signin error: " + e.toString());
    
    break;



bool isLoggedIn = false;

void onLoginStatusChanged(bool isLoggedIn) 
setState(() 
  this.isLoggedIn = isLoggedIn;
);

LoginPage.dart （新）

class _LoginPageState extends State<LoginPage> 
bool loading = false;

bool isLoggedIn = false;

void onLoginStatusChanged(bool isLoggedIn) 
setState(() 
  this.isLoggedIn = isLoggedIn;
);


@override
void initState() 
super.initState();
isSignedIn();


void isSignedIn() async 
setState(() 
  loading = true;
);

isLoggedIn = await _googleSignIn.isSignedIn();

if (isLoggedIn) 
  Navigator.pushReplacement(
      context, MaterialPageRoute(builder: (context) => HomePage()));


setState(() 
  loading = false;
);

我必须添加此代码才能保持登录状态。顺便问一下，我如何才能为 Facebook 做同样的事情？

【参考方案1】：

查看google_sign_in example，下面的sn-p可能是解决你问题的关键。

  @override
  void initState() 
    super.initState();
    _googleSignIn.onCurrentUserChanged.listen((GoogleSignInAccount account) 
      setState(() 
        _currentUser = account;
      );
      if (_currentUser != null) 
        _handleGetContact();
      
    );
    _googleSignIn.signInSilently();
  

我已经实现并测试了它，它按预期工作。

【讨论】：

嗨！感谢您回答我的问题，但仍然无法正常工作。请问我应该把sn-p放在哪里？它应该在登录页面还是主页中？谢谢

把它放在你使用google登录的页面的初始化方法中。例如，如果你在登录页面使用google登录，并且root是StatefulWidget，把它放到initState()

对不起，我已经更新了我的代码，但没有告诉你。对吗？

差不多吧，创建GoogleSignIn实例时不需要指定scopes参数吗？我发现您的代码中有不止一个 GoogleSignInAccount 实例。可能，您应该使用非空 _currentUser 来获取 GoogleSignInAuthentication 的东西，而不是再次登录。

你的意思是这个范围？ GoogleSignIn _googleSignIn = GoogleSignIn( scopes: <String>[ 'email', 'https://www.googleapis.com/auth/contacts.readonly', ], );。一直卡在登录状态，是路由问题吗？你能帮我检查一下代码吗？谢谢

【参考方案2】：

Future googleSignIn() async 
try 
  GoogleSignInAccount googleUser = await _googleSignIn.signIn();
  GoogleSignInAuthentication googleAuth = await googleUser.authentication;

  final AuthCredential credential = GoogleAuthProvider.getCredential(
    accessToken: googleAuth.accessToken,
    idToken: googleAuth.idToken,
  );

  FirebaseUser _user = (await _auth.signInWithCredential(credential)).user;
  assert(_user.email != null);
  assert(_user.displayName != null);
  assert(!_user.isAnonymous);
  assert(await _user.getIdToken() != null);


    DatabaseServices(uid:_user.uid,email: _user.email)
        .updateUserData(_user.displayName,_user.photoUrl);

  print("signed in " + _user.displayName + "\n" + _user.photoUrl);

  return _user;
 catch (e) 
  print(e.toString());
  return null;

【讨论】：

GoogleAuthProvider.getCredentialAPI 改为GoogleAuthProvider.credential

【参考方案3】：

我个人在稳定频道发布 Flutter 后没有尝试过，但您可以存储从 auth 令牌获得的用户信息。

也看看这个：https://medium.com/flutterpub/flutter-how-to-do-user-login-with-firebase-a6af760b14d5