Flutter安卓及iOS海外登录--Google登录最详细流程

import 'package:flutter/material.dart';
import 'package:google_sign_in/google_sign_in.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Google Sign In',
      home: GoogleSignInButton(),
    );
  }
}

class GoogleSignInButton extends StatefulWidget {
  @override
  _GoogleSignInButtonState createState() => _GoogleSignInButtonState();
}

class _GoogleSignInButtonState extends State<GoogleSignInButton> {
  GoogleSignIn _googleSignIn = GoogleSignIn(scopes: ['email']);
  bool isLoggedIn = false;
  GoogleSignInAccount _account;

  // 点击按钮后的处理函数
  void _handleSignIn() async {
    try {
      // 尝试登录
      final GoogleSignInAccount account = await _googleSignIn.signIn();
      setState(() {
        this._account = account;
        isLoggedIn = true;
      });
    } catch (error) {
      print('Error signing in: $error');
    }
  }

  // 点击注销按钮后的处理函数
  void _handleSignOut() {
    _googleSignIn.signOut();
    setState(() {
      isLoggedIn = false;
      _account = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Google Sign In Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            // 如果已登录，显示用户信息和注销按钮
            if (isLoggedIn) ...[
              Text('Signed in as ${_account.displayName}'),
              Text('Email: ${_account.email}'),
              TextButton(
                child: Text('SIGN OUT'),
                onPressed: _handleSignOut,
              ),
            ] else ...[
              // 显示登录按钮
              TextButton(
                child: Text('SIGN IN WITH GOOGLE'),
                onPressed: _handleSignIn,
              ),
            ],
          ],
        ),
      ),
    );
  }
}