Flutter:我无法使用谷歌登录库注销我的应用程序。这个怎么做？

Question

我已经尝试了下面的谷歌登录示例，它工作正常。但是当我将 _handleSignOut() 函数移动到另一个屏幕时，它没有注销。我的要求是登录成功后，我的主页是可见的。在主页的顶部，有一个注销按钮。单击其中，我想使用谷歌注销我的应用程序。

    import 'dart:async';
    import 'dart:convert' show json;
    import "package:http/http.dart" as http;
    import 'package:flutter/material.dart';
    import 'package:google_sign_in/google_sign_in.dart';

    GoogleSignIn _googleSignIn = GoogleSignIn(
      scopes: <String>[
        'email',
        'https://www.googleapis.com/auth/contacts.readonly',
      ],
    );

    void main() {
      runApp(
        MaterialApp(
          title: 'Google Sign In',
          home: SignInDemo(),
        ),
      );
    }

    class SignInDemo extends StatefulWidget {
      @override
      State createState() => SignInDemoState();
    }

    class SignInDemoState extends State<SignInDemo> {
      GoogleSignInAccount _currentUser;
      String _contactText;

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

      Future<void> _handleGetContact() async {
        setState(() {
          _contactText = "Loading contact info...";
        });
        final http.Response response = await http.get(
          'https://people.googleapis.com/v1/people/me/connections'
              '?requestMask.includeField=person.names',
          headers: await _currentUser.authHeaders,
        );
        if (response.statusCode != 200) {
          setState(() {
            _contactText = "People API gave a ${response.statusCode} "
                "response. Check logs for details.";
          });
          print('People API ${response.statusCode} response: ${response.body}');
          return;
        }
        final Map<String, dynamic> data = json.decode(response.body);
        final String namedContact = _pickFirstNamedContact(data);
        setState(() {
          if (namedContact != null) {
            _contactText = "I see you know $namedContact!";
          } else {
            _contactText = "No contacts to display.";
          }
        });
      }

      String _pickFirstNamedContact(Map<String, dynamic> data) {
        final List<dynamic> connections = data['connections'];
        final Map<String, dynamic> contact = connections?.firstWhere(
          (dynamic contact) => contact['names'] != null,
          orElse: () => null,
        );
        if (contact != null) {
          final Map<String, dynamic> name = contact['names'].firstWhere(
            (dynamic name) => name['displayName'] != null,
            orElse: () => null,
          );
          if (name != null) {
            return name['displayName'];
          }
        }
        return null;
      }

      Future<void> _handleSignIn() async {
        try {
          await _googleSignIn.signIn();
        } catch (error) {
          print(error);
        }
      }

      Future<void> _handleSignOut() async {
        _googleSignIn.disconnect();
      }

      Widget _buildBody() {
        if (_currentUser != null) {
          return Column(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: <Widget>[
              ListTile(
                leading: GoogleUserCircleAvatar(
                  identity: _currentUser,
                ),
                title: Text(_currentUser.displayName),
                subtitle: Text(_currentUser.email),
              ),
              const Text("Signed in successfully."),
              Text(_contactText),
              RaisedButton(
                child: const Text('SIGN OUT'),
                onPressed: _handleSignOut,
              ),
              RaisedButton(
                child: const Text('REFRESH'),
                onPressed: _handleGetContact,
              ),
            ],
          );
        } else {
          return Column(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: <Widget>[
              const Text("You are not currently signed in."),
              RaisedButton(
                child: const Text('SIGN IN'),
                onPressed: _handleSignIn,
              ),
            ],
          );
        }
      }

      @override
      Widget build(BuildContext context) {
        return Scaffold(
            appBar: AppBar(
              title: const Text('Google Sign In'),
            ),
            body: ConstrainedBox(
              constraints: const BoxConstraints.expand(),
              child: _buildBody(),
            ));
      }
    }

Answer 1

改用signOut()。如果您使用的是 FirebaseAuth，则需要从两者中注销

Future<void> _handleSignOut() async {
  await FirebaseAuth.instance.signOut();
  await _googleSignIn.signOut();
}