Flutter - googleapis - 如何使用 Gmail Api 阅读电子邮件

Question

Flutter - 如何使用 Gmail Api 阅读电子邮件？

我正在研究 googleapis https://pub.dev/packages/googleapis，但没有关于它是如何完成的文档。

谁能给我一个例子或教程？

Answer 1

这是一个完整的例子：

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:zapit/models/appState.dart';
import 'package:googleapis/gmail/v1.dart' as gMail;

class GmailApiScreen extends StatefulWidget {
  @override
  _GmailApiScreenState createState() => _GmailApiScreenState();
}

class _GmailApiScreenState extends State<GmailApiScreen> {
  gMail.GmailApi gmailApi;
  List<gMail.Message> messagesList = [];
  Future waitForInit;

  @override
  void initState() {
    super.initState();
    waitForInit = init();
  }

  init() async {
    final authHeaders = await AppState.state.googleUser.authHeaders;
    final authenticateClient = GoogleAuthClient(authHeaders);
    gmailApi = gMail.GmailApi(authenticateClient);

    gMail.ListMessagesResponse results =
        await gmailApi.users.messages.list("me");
    for (gMail.Message message in results.messages) {
      gMail.Message messageData =
          await gmailApi.users.messages.get("me", message.id);
      messagesList.add(messageData);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("email")),
      body: buildFutureBuilder(),
    );
  }

  FutureBuilder buildFutureBuilder() {
    return FutureBuilder(
        future: waitForInit,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.done) {
            // If the Future is complete, display the preview.
            List<Widget> messageTxt = [];
            for (var m in messagesList) {
              messageTxt.add(Text(m.snippet));
            }
            return Column(
              children:messageTxt,
            );
          } else {
            // Otherwise, display a loading indicator.
            return Center(child: CircularProgressIndicator());
          }
        });
  }
}

class GoogleAuthClient extends http.BaseClient {
  final Map<String, String> _headers;

  final http.Client _client = new http.Client();

  GoogleAuthClient(this._headers);

  Future<http.StreamedResponse> send(http.BaseRequest request) {
    return _client.send(request..headers.addAll(_headers));
  }
}

googleUser 是通过在以下代码中调用 ensureLoggedInOnStartUp 创建的：

import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:googleapis/gmail/v1.dart' as gMail;

final FirebaseAuth _auth = FirebaseAuth.instance;
final GoogleSignIn googleSignIn = GoogleSignIn.standard(scopes: [gMail.GmailApi.GmailReadonlyScope]);

Future<GoogleSignInAccount> ensureLoggedInOnStartUp() async {
  // That class has a currentUser if there's already a user signed in on
  // this device.
  try {
    GoogleSignInAccount googleSignInAccount = googleSignIn.currentUser;
    if (googleSignInAccount == null) {
      // but if not, Google should try to sign one in whos previously signed in
      // on this phone.
      googleSignInAccount = await googleSignIn.signInSilently();
      if (googleSignInAccount == null) return null;

      final GoogleSignInAuthentication googleSignInAuthentication =
          await googleSignInAccount.authentication;

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

      final UserCredential authResult =
          await _auth.signInWithCredential(credential);
      final User user = authResult.user;

      assert(!user.isAnonymous);
      assert(await user.getIdToken() != null);

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

      return googleSignInAccount;
    }
  }  catch (e) { //on PlatformException
    print(e);
  }
  return null;
}

Future<GoogleSignInAccount> signInWithGoogle() async {
  try {
    final GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();

    final GoogleSignInAuthentication googleSignInAuthentication =
        await googleSignInAccount.authentication;

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

    // throws FirebaseException when no internet connection
    final UserCredential authResult = await _auth.signInWithCredential(credential);
    final User user = authResult.user;

    assert(!user.isAnonymous);
    assert(await user.getIdToken() != null);

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

    return googleSignInAccount;
  } catch (e,s) {
    print(e);
    print(s);
    return null;
  }
}

void signOutGoogle() async {
  await googleSignIn.signOut();

  print("User Sign Out");
}