如何在课程之间传递位置更新结果

问题描述

我正在尝试构建一个应用程序，以提供围绕固定标记航行的导航。它将有一个仪表板，提供速度，航向，指向下一个标记的值，并允许从列表中选择下一个标记。我有一个工作版本，其中所有LocationServices都位于MainActivity中，但是我想将位置代码移到一个单独的类中，并将位置包连续传递回MainActivity进行显示。为了解决这个问题，我从this youtube video重新创建了一个简单的应用，其中包含一些我的小修改。该应用程序成功运行，并在LocationServices类内生成的logcat消息连续产生纬度和经度。如何将这些信息（locationResult）返回给MainActivity，以便提取需要在UI上显示的值？

我已经在该主题上进行了广泛的搜索，并尝试了很多方法，但没有发现任何可以满足我需求的东西。我已经尝试阅读文档，但是找不到关于如何执行我认为应该是常见任务的解释。

一般来说，我是Java和OOP的新手，这是我的第一篇文章，所以请忍着无知。

MainActivity.java

package com.sail.gps_ext3;

import ...

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_CODE_LOCATION_PERMISSION = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        startLocationService();

//...

    }

    @Override
    public void onRequestPermissionsResult(int requestCode,@NonNull String[] permissions,@NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode,permissions,grantResults);
        if (requestCode == REQUEST_CODE_LOCATION_PERMISSION && grantResults.length > 0) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                startLocationService();
            } else {
                Toast.makeText(this,"Permission denied!",Toast.LENGTH_SHORT).show();
            }
        }
    }

    private boolean isLocationServiceRunning() {
        ActivityManager activityManager =
                (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        if (activityManager != null) {
            Log.e("Loc service running","");
            for (ActivityManager.RunningServiceInfo service :
                    activityManager.getRunningServices(Integer.MAX_VALUE)) {
                if (LocationService.class.getName().equals(service.service.getClassName())) {
                    if (service.foreground) {
                        return true;
                    }
                }
            }
            return false;
        }
        return false;
    }

    private void startLocationService() {
        if (!isLocationServiceRunning()) {
            Intent intent = new Intent(getApplicationContext(),LocationService.class);
            intent.setAction(Constants.ACION_START_LOCATION_SERVICE);
            startService(intent);
            Toast.makeText(this,"Location service started",Toast.LENGTH_SHORT).show();
        }
    }

//...

}

LocationService.java

package com.sail.gps_ext3;

import ...

public class LocationService extends Service {

    private LocationCallback locationCallback = new LocationCallback() {
        @Override
        public void onLocationResult(LocationResult locationResult) {
            super.onLocationResult(locationResult);
            if(locationResult != null && locationResult.getLastLocation() != null) {

                double latitude = locationResult.getLastLocation().getLatitude();
                double longitude = locationResult.getLastLocation().getLongitude();
                Log.d("LOCATION_UPDATE",latitude + "," + longitude);
            }
        }
    };

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        throw new UnsupportedOperationException("Not yet implemented");
    }

    private void startLocationService() {
        String channelId = "location_notification_channel";
        notificationmanager notificationmanager =
                (notificationmanager) getSystemService(Context.NOTIFICATION_SERVICE);
        Intent resultIntent = new Intent();
        PendingIntent pendingIntent = PendingIntent.getActivity(
                getApplicationContext(),resultIntent,PendingIntent.FLAG_UPDATE_CURRENT
                );
        NotificationCompat.Builder builder = new NotificationCompat.Builder(
                getApplicationContext(),channelId
        );

//...

        LocationRequest locationRequest = new LocationRequest();
        locationRequest.setInterval(4000);
        locationRequest.setFastestInterval(2000);
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

        LocationServices.getFusedLocationProviderClient(this)
                .requestLocationUpdates(locationRequest,locationCallback,Looper.getMainLooper());
        startForeground(Constants.LOCATION_SERVICE_ID,builder.build());
    }

    private void stopLocationService() {
        LocationServices.getFusedLocationProviderClient(this)
                .removeLocationUpdates(locationCallback);
        stopForeground(true);
        stopSelf();
    }

    @Override
    public int onStartCommand(Intent intent,int flags,int startId) {
        if (intent != null) {
            String action = intent.getAction();
            if (action != null) {
                if (action.equals(Constants.ACION_START_LOCATION_SERVICE)) {
                    startLocationService();
                }else if (action.equals(Constants.ACTION_STOP_LOCATION_SERVICE)) {
                    stopLocationService();
                }
            }
        }
        return super.onStartCommand(intent,flags,startId);
    }
}

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

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