如果我使用workmanager包，Flutter引擎停止运行并退出应用程序

Question

只有当我使用

workmanager

软件包时才会发生这种情况，我认为与某些谷歌软件包或

flutter_tesseract_ocr

有冲突

void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) {
    print('I dont know what happens so help');
    return Future.value(true);
  });
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseMessaging.onBackgroundMessage(_firebasePushHandler);
  MobileAds.instance.initialize();
  await CacheHelper.init();
  await EasyLocalization.ensureInitialized();
  await CacheHelper.removeData('isshown');
  DioHelper.init();
//Work manager initializtion
  Workmanager().initialize(
    callbackDispatcher, // The top level function, aka callbackDispatcher
  );
  index = CacheHelper.getData(key: 'index') ?? 0;
  String? uid = CacheHelper.getData(key: 'uid');
  await NotificationApi.init();
  BlocOverrides.runZoned(
    () {
      runApp(
        EasyLocalization(
            supportedLocales: const [Locale('en'), Locale('ar')],
            path: 'assets/lang', // <-- change the path of the translation files
            assetLoader: const CodegenLoader(),
            fallbackLocale: const Locale('en'),
            child: MyApp(uid)),
      );
    },
    blocObserver: MyBlocObserver(),
  );
}

///this is code where I register it
Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        HapticFeedback.lightImpact();
        setState(() {
          controller!.forward();
        });
        // Workmanager().cancelAll();
        Workmanager().registerOneOffTask('awsomeNotification', 'notify',
            initialDelay: const Duration(seconds: 5));
      },
      child: CardStack(controller!, widget.slideNum, widget.slideText),
    );
  }

W/MediaSessionCompat(12770): Couldn't find a unique registered media button receiver in the given context.
W/FlutterJNI(12770): FlutterJNI.loadLibrary called more than once
I/ResourceExtractor(12770): Found extracted resources res_timestamp-1-1656733798661
W/FlutterJNI(12770): FlutterJNI.prefetchDefaultFontManager called more than once
W/FlutterJNI(12770): FlutterJNI.init called more than once
D/AndroidRuntime(12770): Shutting down VM
E/AndroidRuntime(12770): FATAL EXCEPTION: main
E/AndroidRuntime(12770): Process: com.areading.amaa, PID: 12770
E/AndroidRuntime(12770): java.lang.NullPointerException: Attempt to invoke virtual method 'void com.googlecode.tesseract.android.TessBaseAPI.recycle()' on a null object reference
E/AndroidRuntime(12770):    at io.paratoner.flutter_tesseract_ocr.FlutterTesseractOcrPlugin.onDetachedFromEngine(FlutterTesseractOcrPlugin.java:42)
E/AndroidRuntime(12770):    at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.remove(FlutterEngineConnectionRegistry.java:270)
E/AndroidRuntime(12770):    at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.remove(FlutterEngineConnectionRegistry.java:280)
E/AndroidRuntime(12770):    at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.removeAll(FlutterEngineConnectionRegistry.java:288)
E/AndroidRuntime(12770):    at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.destroy(FlutterEngineConnectionRegistry.java:121)
E/AndroidRuntime(12770):    at io.flutter.embedding.engine.FlutterEngine.destroy(FlutterEngine.java:425)
E/AndroidRuntime(12770):    at be.tramckrijte.workmanager.BackgroundWorker.stopEngine$lambda-2(BackgroundWorker.kt:137)
E/AndroidRuntime(12770):    at be.tramckrijte.workmanager.BackgroundWorker.lambda$u5fs2CPxJ29Hdjbap5WYUt2tGrg(Unknown Source:0)
E/AndroidRuntime(12770):    at be.tramckrijte.workmanager.-$$Lambda$BackgroundWorker$u5fs2CPxJ29Hdjbap5WYUt2tGrg.run(Unknown Source:2)
E/AndroidRuntime(12770):    at android.os.Handler.handleCallback(Handler.java:938)
E/AndroidRuntime(12770):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(12770):    at android.os.Looper.loopOnce(Looper.java:210)
E/AndroidRuntime(12770):    at android.os.Looper.loop(Looper.java:299)
E/AndroidRuntime(12770):    at android.app.ActivityThread.main(ActivityThread.java:8168)
E/AndroidRuntime(12770):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(12770):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:556)
E/AndroidRuntime(12770):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1037)
I/WM-WorkerWrapper(12770): Worker result SUCCESS for Work [ id=58f0ee16-1de5-42d8-ae78-1d789ea5125f, tags={ be.tramckrijte.workmanager.BackgroundWorker } ]
D/OOMEventManagerFK(12770): checkEventAndDumpForJE: 0
I/Process (12770): Sending signal. PID: 12770 SIG: 9
Lost connection to device.
Exited (sigterm)

Answer 1

由于启动了后台任务 - 调用了

onDetachedFromEngine

方法 - 在用于 Flutter 的 TessOCR 原始插件存储库中，没有空安全检查。

我通过分叉 TessOCR 存储库为此提供了一个简单的补丁： https://github.com/EthanKrimer/tesseract_ocr/compare/5510f1345089ae617744a401710e0ae7fb87c43a...923ebd1c302363e3de61e9693d6eb36617908073

为了在您的 flutter 应用程序中使用此修复程序： 将其添加到您的

pubspec.yaml

dependencies:
   flutter_tesseract_ocr:
        git:
            url: https://github.com/EthanKrimer/tesseract_ocr.git
            ref: master

然后运行

pub upgrade