Flutter集成Firebase实现Google登录报Expecting binder but got null

问题背景 #

移动应用开发新手使用Flutter结合Firebase Auth实现Google社交登录功能，参考官方文档编写的代码逻辑如下：

main.dart 代码 #

import 'package:atlas_app/auth/signup.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );

  FirebaseAuth.instance.useAuthEmulator('10.0.2.2', 9099);

  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: const SignUp());
  }
}

signin.dart 代码 #

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:flutter_signin_button/button_list.dart';
import 'package:flutter_signin_button/button_view.dart';
import 'package:google_sign_in/google_sign_in.dart';

class SignUp extends StatefulWidget {
  const SignUp({Key? key}) : super(key: key);

  @override
  State<SignUp> createState() => _SignUpState();
}

class _SignUpState extends State<SignUp> {
  FirebaseAuth auth = FirebaseAuth.instance;

Future<UserCredential> signInWithGoogle() async {
  final GoogleSignInAccount? googleUser = await GoogleSignIn().signIn();
  final GoogleSignInAuthentication? googleAuth = await googleUser?.authentication;
  final credential = GoogleAuthProvider.credential(
    accessToken: googleAuth?.accessToken,
    idToken: googleAuth?.idToken,
  );
  return await FirebaseAuth.instance.signInWithCredential(credential);
}

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.blue,
          elevation: 8,
          title: const Text("Sign Up"),
        ),
        body: Container(
          padding: const EdgeInsets.symmetric(vertical: 20, horizontal: 50),
          child: Form(
              child: Column(
            children: [
              SignInButton(
                Buttons.Google,
                onPressed: () async => {signInWithGoogle()},
              )
            ],
          )),
        ));
  }
}

故障现象 #

本以为该段逻辑简单的代码可正常运行，但在搭载Android API 33（arm64架构）的Pixel 4安卓模拟器上点击登录按钮时，应用发生崩溃，调试控制台输出错误信息如下：

W/Parcel  (13587): Expecting binder but got null!
D/EGL_emulation(13587): app_time_stats: avg=697.35ms min=151.31ms max=1243.39ms count=2
E/JavaBinder(13587): !!! FAILED BINDER TRANSACTION !!!  (parcel size = 324)
W/GmsClient(13587): IGmsServiceBroker.getService failed
W/GmsClient(13587): android.os.DeadObjectException: Transaction failed on small parcel; remote process probably died, but this could also be caused by running out of binder buffe
W/GmsClient(13587):     at android.os.BinderProxy.transactNative(Native Method)
W/GmsClient(13587):     at android.os.BinderProxy.transact(BinderProxy.java:584)
W/GmsClient(13587):     at com.google.android.gms.common.internal.zzac.getService(com.google.android.gms:play-services-basement@@18.0.0:8)
W/GmsClient(13587):     at com.google.android.gms.common.internal.BaseGmsClient.getRemoteService(com.google.android.gms:play-services-basement@@18.0.0:14)
W/GmsClient(13587):     at com.google.android.gms.common.api.internal.zabt.run(com.google.android.gms:play-services-base@@18.0.1:7)
W/GmsClient(13587):     at android.os.Handler.handleCallback(Handler.java:942)
W/GmsClient(13587):     at android.os.Handler.dispatchMessage(Handler.java:99)
W/GmsClient(13587):     at android.os.Looper.loopOnce(Looper.java:201)
W/GmsClient(13587):     at android.os.Looper.loop(Looper.java:288)
W/GmsClient(13587):     at android.os.HandlerThread.run(HandlerThread.java:67)
W/Parcel  (13587): Expecting binder but got null!
D/EGL_emulation(13587): eglCreateContext: 0xb400006ff0487dd0: maj 3 min 0 rcv 3
D/EGL_emulation(13587): eglCreateContext: 0xb400006ff0489e10: maj 3 min 0 rcv 3
D/HostConnection(13587): createUnique: call
D/HostConnection(13587): HostConnection::get() New Host Connection established 0xb400006ff0488f10, tid 13652
D/HostConnection(13587): HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_vulkan_queue_submit_with_commands ANDROID_EMU_sync_buffer_data ANDROID_EMU_read_color_buffer_dma GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_3_0
D/EGL_emulation(13587): eglMakeCurrent: 0xb400006ff0489e10: ver 3 0 (tinfo 0x720c8be280) (first time)
D/HostConnection(13587): createUnique: call
D/HostConnection(13587): HostConnection::get() New Host Connection established 0xb400006ff0488010, tid 13651
D/HostConnection(13587): HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_has_shared_slots_host_memory_allocator ANDROID_EMU_vulkan_free_memory_sync ANDROID_EMU_vulkan_shader_float16_int8 ANDROID_EMU_vulkan_async_queue_submit ANDROID_EMU_vulkan_queue_submit_with_commands ANDROID_EMU_sync_buffer_data ANDROID_EMU_read_color_buffer_dma GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_3_0
D/EGL_emulation(13587): eglMakeCurrent: 0xb400006ff0487dd0: ver 3 0 (tinfo 0x720c8be300) (first time)
D/EGL_emulation(13587): eglCreateContext: 0xb400006ff0486f90: maj 3 min 0 rcv 3
E/JavaBinder(13587): !!! FAILED BINDER TRANSACTION !!!  (parcel size = 324)
W/GmsClient(13587): IGmsServiceBroker.getService failed
W/GmsClient(13587): android.os.DeadObjectException: Transaction failed on small parcel; remote process probably died, but this could also be caused by running out of binder buffe
......

故障原因与修复方案 #

该崩溃和Flutter业务代码逻辑无关，核心是模拟器环境的Google服务异常，按以下优先级排查修复：

• 检查模拟器镜像类型
  打开Android Studio的AVD管理器，查看当前使用的Pixel 4模拟器镜像，只有镜像旁标注Play Store图标的版本才内置完整Google服务框架，纯AOSP镜像、仅标注Google APIs的镜像都可能出现服务通信失败问题。如果镜像不对，直接删除后重新选择带Play Store标识的arm64架构API 33/34镜像创建即可。
• 更新Google服务组件
  如果已经使用带Play Store的镜像，启动模拟器后打开内置的Play Store，进入「我的应用和游戏」页面，将Google Play服务、Google Play商店全部更新到最新版本，更新完成后冷启动模拟器再测试。
• 排查配置冲突
  • 确认Firebase控制台注册Android应用时填入的包名和项目本地包名一致，且已将下载的google-services.json文件放到Android项目的app模块根目录下
  • 确认Gradle配置正确：项目级build.gradle依赖中已添加Google服务插件，app级build.gradle文件末尾已应用com.google.gms.google-services插件
  • 注意：Google第三方登录流程不支持走Firebase Auth本地模拟器，测试Google登录时先注释掉FirebaseAuth.instance.useAuthEmulator('10.0.2.2', 9099);这行代码，避免服务路由冲突。
• 代码写法优化（非崩溃原因，仅规范写法）
  当前登录按钮的回调写法不规范，箭头函数后无需加花括号，修改为：

  SignInButton(
    Buttons.Google,
    onPressed: () async => await signInWithGoogle(),
  )
  

  也可以使用普通异步函数写法，方便后续加入加载状态、登录结果处理逻辑。

内容的提问来源于stack exchange，提问作者Takuya.N