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首页 > 解决方案 > “试图向 Flutter 发送平台消息，但 FlutterJNI 与原生 C++ 分离。” 启动后台服务并关闭应用程序后

android - “试图向 Flutter 发送平台消息，但 FlutterJNI 与原生 C++ 分离。” 启动后台服务并关闭应用程序后

问题描述

我正在尝试构建一个使用一些包作为位置（https://pub.dev/packages/location）和指南针（https://pub.dev/packages/flutter_compass）的应用程序，并保持后台服务跟踪用户位置. 一切正常，直到我启动服务来跟踪位置。

当服务处于活动状态时，整个应用程序永远不会停止，例如，当我在没有服务的情况下关闭应用程序时，指南针也会停止，但随着服务的运行，指南针也会继续运行。实际上它返回一个错误“尝试向 Flutter 发送平台消息，但 FlutterJNI 已与本机 C++ 分离。无法发送。频道：hemanthraj/flutter_compass”。位置发生了同样的事情：“尝试向 Flutter 发送平台消息，但 FlutterJNI 与本机 C++ 分离。无法发送。频道：lyokone/locationstream”。在此之后，即使我再次打开该项目，它也不再起作用......我正在尝试使服务完全独立于项目的其余部分。

我将向您展示服务实现（Android）

public class CompassApplication extends FlutterApplication {

    @Override
    public void onCreate() {
        super.onCreate();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel("messages", "Messages", NotificationManager.IMPORTANCE_LOW);
            NotificationManager manager = getSystemService(NotificationManager.class);
            if (manager != null) {
                manager.createNotificationChannel(channel);
            }
        }
    }
}

class MainActivity: FlutterActivity() {

    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine)

        val intent = Intent(this, LocationService::class.java)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(intent)
        } else {
            startService(intent)
        }
    }
}

public class LocationService extends Service {

    static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10 * 60 * 1000; // 10 minutes
    static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS = UPDATE_INTERVAL_IN_MILLISECONDS / 2;

    private LocationRequest mLocationRequest;
    private FusedLocationProviderClient mFusedLocationClient;
    private LocationCallback mLocationCallback;

    @Override
    public void onCreate() {
        super.onCreate();

        mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

        mLocationCallback = new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                super.onLocationResult(locationResult);
                onNewLocation(locationResult.getLastLocation());
            }
        };

        createLocationRequest();
        getLastLocation();
        requestLocationUpdates();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "messages")
                    .setSmallIcon(R.mipmap.ic_launcher_foreground);

            startForeground(101, builder.build());
        }
    }

    private void createLocationRequest() {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
        mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }

    private void getLastLocation() {
        try {
            mFusedLocationClient.getLastLocation()
                    .addOnCompleteListener(task -> {
                        if (task.isSuccessful() && task.getResult() != null) {
                            onNewLocation(task.getResult());
                        }
                    });
        } catch (SecurityException ignored) {}
    }

    public void requestLocationUpdates() {
        Utils.setRequestingLocationUpdates(this, true);
        startService(new Intent(getApplicationContext(), LocationUpdatesService.class));
        try {
            mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
        } catch (SecurityException unlikely) {
            Utils.setRequestingLocationUpdates(this, false);
        }
    }

    private void onNewLocation(Location location) {
        // TODO: deal with current location
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

另一个问题是即使我不关闭应用程序，它也会消耗大量电池。谢谢！

标签： androidflutterdartservicebackground

解决方案

将以下代码添加到本机 android mainActivity.kt

package <your.package.name>

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

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