Flutter开发中，google_sign_in安装指引里的“register your application”指什么？

Hey there! I totally get the frustration of following official docs that push Firebase when you don't want to use it. Let's walk through how to set up Google Sign-In for your Flutter app, register your app properly without Firebase, and fetch Google Sheets data using the googleapis package.

Forget Firebase—we'll handle this directly in Google Cloud Console:

• Create a new project (or use an existing one).
• Navigate to API & Services > OAuth Consent Screen:
  • Choose "External" (for public apps) or "Internal" (if only for your organization's users).
  • Fill in basic details like your app name, support email, and any required contact info.
  • If you picked "External", add test users (only these users can sign in until your app is verified by Google).
• Go to API & Services > Credentials:
  • Click Create Credentials > OAuth client ID.
  • Select your platform (Android, iOS, or Web):
    • Android: Enter your app's package name (e.g., com.yourcompany.yourapp) and SHA-1 fingerprint. You can get the debug SHA-1 with this command:

      keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android
      

      Don't forget to add your release SHA-1 later if you plan to publish the app.
    • iOS: Enter your app's Bundle ID, then note the URL Scheme provided (it looks like com.googleusercontent.apps.[your-client-id]—you'll need this for Info.plist).
  • Once created, save your client ID—you'll need it for your Flutter project.
• Finally, enable the Google Sheets API in the Cloud Console (search for it under API & Services > Library, then click "Enable").

First, add the required dependencies to your pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  google_sign_in: ^5.4.0
  googleapis: ^10.0.0
  googleapis_auth: ^1.4.0 # Needed to create an authenticated client for Google APIs

Android Setup #

Open android/app/src/main/AndroidManifest.xml and add this meta-data inside the <application> tag:

<meta-data
    android:name="com.google.android.gms.auth.api.signin.client_id"
    android:value="YOUR_ANDROID_CLIENT_ID"/>

iOS Setup #

Open ios/Runner/Info.plist and add these entries:

<key>GIDClientID</key>
<string>YOUR_IOS_CLIENT_ID</string>
<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>com.googleusercontent.apps.[YOUR_CLIENT_ID]</string>
    </array>
  </dict>
</array>

Here's a complete example to handle sign-in and retrieve data from a Google Sheet:

import 'package:flutter/material.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:googleapis/sheets/v4.dart';
import 'package:googleapis_auth/auth.dart';
import 'package:googleapis_auth/auth_io.dart';

class GoogleSheetsDemo extends StatefulWidget {
  const GoogleSheetsDemo({super.key});

  @override
  State<GoogleSheetsDemo> createState() => _GoogleSheetsDemoState();
}

class _GoogleSheetsDemoState extends State<GoogleSheetsDemo> {
  final GoogleSignIn _googleSignIn = GoogleSignIn(
    scopes: [
      SheetsApi.spreadsheetsReadonlyScope, // Use spreadsheetsScope for read/write access
    ],
    // Add clientId here only if you're targeting Web; mobile uses the Manifest/Info.plist config
    // clientId: "YOUR_WEB_CLIENT_ID",
  );

  String? _sheetData;

  Future<void> _signInAndFetchSheets() async {
    try {
      // Trigger sign-in flow
      final GoogleSignInAccount? account = await _googleSignIn.signIn();
      if (account == null) {
        setState(() => _sheetData = "Sign-in canceled.");
        return;
      }

      // Get authentication credentials
      final GoogleSignInAuthentication auth = await account.authentication;
      final AuthClient client = GoogleAuthClient(auth.accessToken!);

      // Initialize Sheets API client
      final sheetsApi = SheetsApi(client);

      // Replace with your Google Sheet ID and range
      const spreadsheetId = "YOUR_SPREADSHEET_ID";
      const range = "Sheet1!A1:C10"; // Adjust to your desired range

      // Fetch data
      final response = await sheetsApi.spreadsheets.values.get(spreadsheetId, range);
      final values = response.values;

      if (values == null || values.isEmpty) {
        setState(() => _sheetData = "No data found in the sheet.");
        return;
      }

      // Format data for display
      String formattedData = "";
      for (var row in values) {
        formattedData += "${row.join(", ")}\n";
      }
      setState(() => _sheetData = formattedData);
    } catch (e) {
      setState(() => _sheetData = "Error: $e");
    }
  }

  Future<void> _signOut() async {
    await _googleSignIn.signOut();
    setState(() => _sheetData = null);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text("Google Sheets Demo")),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (_sheetData == null)
              ElevatedButton(
                onPressed: _signInAndFetchSheets,
                child: const Text("Sign in with Google & Fetch Data"),
              )
            else ...[
              Text(_sheetData!),
              const SizedBox(height: 20),
              ElevatedButton(
                onPressed: _signOut,
                child: const Text("Sign Out"),
              ),
            ]
          ],
        ),
      ),
    );
  }
}

Key Notes: #

• Spreadsheet ID: Find this in your Google Sheet's URL—it's the long string between /d/ and /edit.
• Permissions: Use SheetsApi.spreadsheetsScope if you need to edit the sheet, or spreadsheetsReadonlyScope for read-only access.
• OAuth Verification: If you're building a public app, you'll need to submit your OAuth consent screen for Google's verification to let non-test users sign in. Until then, only your added test users can access the app.

内容的提问来源于stack exchange，提问作者Jose M Vidal