Flutter集成Google Maps失败求助：地图空白并抛出异常

我正在开发一款通过便捷导航解决公共交通问题的应用，目前处于开发初期，遇到Google Maps插件集成问题。已在Google Cloud创建Google Maps专用API Key，期望实现带标记的交互式地图，但首先需成功加载基础地图。

开发环境 #

• Windows 11 + Visual Studio
• 模拟器：Pixel 8 Pro

main.dart代码 #

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MapScreen(),
    );
  }
}

class MapScreen extends StatefulWidget {
  @override
  _MapScreenState createState() => _MapScreenState();
}

class _MapScreenState extends State<MapScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Google Maps in Flutter')),
      body: GoogleMap(
        initialCameraPosition: CameraPosition(
          target: LatLng(37.7749, -122.4194), // 旧金山坐标
          zoom: 12,
        ),
      ),
    );
  }
}

AndroidManifest.xml配置（已添加API Key） #

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application
        android:label="test1"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">

          <meta-data
              android:name="com.google.android.geo.API_KEY"
              android:value="ActualAPIKeyIDecidedToHide" />
              
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">

            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
    <!-- Required to query activities that can process text, see:
         https://developer.android.com/training/package-visibility?hl=en and
         https://developer.android.com/reference/android/content/Intent#ACTION_PROCESS_TEXT.

         In particular, this is used by the Flutter engine in io.flutter.plugin.text.ProcessTextPlugin. -->
    <queries>
        <intent>
            <action android:name="android.intent.action.PROCESS_TEXT"/>
            <data android:mimeType="text/plain"/>
        </intent>
    </queries>
</manifest>

运行异常情况 #

应用仅显示AppBar，地图区域空白，调试控制台抛出以下异常：

V/GoogleMapController( 5590): Controller was disposed before GoogleMap was ready.
E/PlatformViewsController( 5590): Disposing platform view threw an exception
E/PlatformViewsController( 5590): java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.LinkedList.isEmpty()' on a null object reference
E/PlatformViewsController( 5590):   at com.google.android.gms.dynamic.DeferredLifecycleHelper.zae(com.google.android.gms:play-services-base@@18.0.1:1)
E/PlatformViewsController( 5590):   at com.google.android.gms.dynamic.DeferredLifecycleHelper.onDestroy(com.google.android.gms:play-services-base@@18.0.1:2)
E/PlatformViewsController( 5590):   at com.google.android.gms.maps.MapView.onDestroy(com.google.android.gms:play-services-maps@@18.2.0:1)
E/PlatformViewsController( 5590):   at io.flutter.plugins.googlemaps.GoogleMapController.destroyMapViewIfNecessary(GoogleMapController.java:914)
E/PlatformViewsController( 5590):   at io.flutter.plugins.googlemaps.GoogleMapController.dispose(GoogleMapController.java:600)
E/PlatformViewsController( 5590):   at io.flutter.plugin.platform.PlatformViewsController$1.dispose(PlatformViewsController.java:256)
E/PlatformViewsController( 5590):   at io.flutter.embedding.engine.systemchannels.PlatformViewsChannel$1.dispose(PlatformViewsChannel.java:150)
E/PlatformViewsController( 5590):   at io.flutter.embedding.engine.systemchannels.PlatformViewsChannel$1.onMethodCall(PlatformViewsChannel.java:58)
E/PlatformViewsController( 5590):   at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:267)
E/PlatformViewsController( 5590):   at io.flutter.embedding.engine.dart.DartMessenger.invokeHandler(DartMessenger.java:292)
E/PlatformViewsController( 5590):   at io.flutter.embedding.engine.dart.DartMessenger.lambda$dispatchMessageToQueue$0$io-flutter-embedding-engine-dart-DartMessenger(DartMessenger.java:319)
E/PlatformViewsController( 5590):   at io.flutter.embedding.engine.dart.DartMessenger$$ExternalSyntheticLambda0.run(Unknown Source:12)
E/PlatformViewsController( 5590):   at android.os.Handler.handleCallback(Handler.java:942)
E/PlatformViewsController( 5590):   at android.os.Handler.dispatchMessage(Handler.java:99)
E/PlatformViewsController( 5590):   at android.os.Looper.loopOnce(Looper.java:201)
E/PlatformViewsController( 5590):   at android.os.Looper.loop(Looper.java:288)
E/PlatformViewsController( 5590):   at android.app.ActivityThread.main(ActivityThread.java:7872)
E/PlatformViewsController( 5590):   at java.lang.reflect.Method.invoke(Native Method)
E/PlatformViewsController( 5590):   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
E/PlatformViewsController( 5590):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)
D/EGL_emulation( 5590): app_time_stats: avg=22221.97ms min=118.97ms max=44324.98ms count=2

════════ Exception caught by widgets library ═══════════════════════════════════
The following NoSuchMethodError was thrown building MyApp(dirty):
No constructor '' declared in class 'null'.
Receiver: null
Tried calling: new ()

The relevant error-causing widget was:
    MyApp MyApp:file:///C:/Users/alexa/OneDrive/Skrivbord/test1/lib/main.dart:4:23

When the exception was thrown, this was the stack:
#0      NoSuchMethodError._throwNew (dart:core-patch/errors_patch.dart:191:5)
#1      MyApp.build (package:test1/main.dart:10:13)
#2      StatelessElement.build (package:flutter/src/widgets/framework.dart:5550:49)

已尝试的解决方法 #

• 参考多篇在线教程
• 创建新项目复制代码
• 执行flutter clean和flutter run
• 重新导入Google Maps插件
• 修改settings.gradle中的minSdkVersion（解决了一个旧错误，但出现当前异常）

内容的提问来源于stack exchange，提问作者Alexandru Cretu