Question

我是Android的新手，从iOS迁移。我正在开发一个健身应用程序（4.3+）来计算用户位置并跟踪它。一切都很好，除非应用程序进入后台，我停止接收位置更新。

我目前正在使用从我的GPSManager类到UserFitness类的BroadcastReceiver。在GPSManager类中，我启动了LocationManager，其他一切包括开始位置更新。然后，每当新的位置更新可用并且在此处完成一些计算，存储并显示给用户时，它就被广播到UserFitness类。我已经研究过我需要为LocationManager实现一个Service才能在后台工作，但我不知道如何为我当前的代码实现它。我的所有代码都在下面。

任何人都可以告诉我如何根据我的代码在后台获取位置更新，这是否可以在没有系统破坏过程的情况下一次大约4个小时？如果系统确实破坏了它，那么可以采取哪些措施让流程尽快回到之前的状态？

谢谢！

CODE

GPSManager.java

public class GPSManager{

private static final String TAG = "GPSManager";
public static final String ACTION_LOCATION = "com.fitnesstracker.ACTION_LOCATION";

private static GPSManager sGPSManager;
private Context mAppContext;
private LocationManager mLocationManager;
private Location mLastLocation;

private GPSManager (Context appContext,GpsStatus.Listener listen)
{
    mAppContext = appContext;
    mLocationManager = (LocationManager) mAppContext.getSystemService(Context.LOCATION_SERVICE);
    mLocationManager.addGpsStatusListener(listen);
}

public static GPSManager get (Context c,GpsStatus.Listener listen)
{
    if (sGPSManager == null)
    {
        //USE THE APPLICATION CONTEXT TO AVOID LEAKING ACTIVITIES
        sGPSManager = new GPSManager(c,listen);
    }
    return sGPSManager;
}

private PendingIntent getLocationPendingIntent (boolean shouldCreate)
{
    Intent broadcast = new Intent(ACTION_LOCATION);
    int flags = shouldCreate ? 0 : PendingIntent.FLAG_NO_CREATE;

    return PendingIntent.getBroadcast(mAppContext, 0, broadcast, flags);
}

public void startLocationUpdates()
{
    String provider = LocationManager.GPS_PROVIDER;

    //GET LAST KNOWN LOCATION AND BROADCAST IF THERE IS ONE

    mLastLocation = mLocationManager.getLastKnownLocation(provider);
    if (mLastLocation != null)
    {
        mLastLocation.setTime(System.currentTimeMillis());
        broadcastLocation(mLastLocation);
    }

    //START UPDATES FROM LOCATION MANAGER
    PendingIntent pi = getLocationPendingIntent(true);
    mLocationManager.requestLocationUpdates(provider,0,0,pi);
}

private void broadcastLocation (Location location)
{
    Intent broadcast = new Intent(ACTION_LOCATION);
    broadcast.putExtra(LocationManager.KEY_LOCATION_CHANGED, location);
    mAppContext.sendBroadcast(broadcast);
}

public void stopLocationUpdates()
{
    PendingIntent pi = getLocationPendingIntent(false);

    if (pi != null)
    {
        mLocationManager.removeUpdates(pi);
        pi.cancel();
    }
}
}

UserFitness.java

public class UserFitness extends Activity  {

private GPSManager mGPSManager;
private Location mLastLocation;
private boolean isGPSReady;
private float mLastLocationMillis;

private GpsStatus.Listener mGPSListener = new GpsStatus.Listener()
{
    public void onGpsStatusChanged(int event) {
        switch (event) {
            case GpsStatus.GPS_EVENT_SATELLITE_STATUS:
             if (mLastLocation != null)

             isGPSReady = (SystemClock.elapsedRealtime() - mLastLocationMillis) < 13000;

             if (isGPSReady) { // A fix has been acquired.
                calculateUserDistance()
            } else { // The fix has been lost.
                Toast.makeText(getApplicationContext(), "GPS Signal Fix Lost", Toast.LENGTH_SHORT).show();
            }
            break;
            case GpsStatus.GPS_EVENT_FIRST_FIX:

            isGPSReady = true;
            break;
        }
    }
};

private BroadcastReceiver mLocationReceiver = new LocationReceiver()
{
    @Override
    protected void onLocationReceived (Context context, Location loc)
    {
        mLastLocationMillis = SystemClock.elapsedRealtime();
        mLastLocation = loc;
        Log.d("OnLocationReceived",mLastLocation.toString());
    }

    protected void onProviderEnabledChanged (boolean enabled)
    {

    }
};

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fitness);
     mGPSManager = GPSManager.get(this,mGPSListener);
}

@Override
public void onStart()
{
    super.onStart();
    this.registerReceiver(mLocationReceiver, new IntentFilter(GPSManager.ACTION_LOCATION));
    mGPSManager.startLocationUpdates();
}

@Override
public void onStop()
{
    this.unregisterReceiver(mLocationReceiver);
    super.onStop();
}

/* private void calculateUserDistance() */

Answer 1

哦，不！这是一种处理位置更新的旧方法！首先，你必须熟悉this guideline。本指南使用LocationClient描述了位置跟踪策略。

请注意，甚至有更新的方式来跟踪当前位置 - 使用GoogleApiClient和LocationServices，但由于缺少适当的文档，您现在可以忽略它：（< / em>的

返回LocationClient - 有两种方法可以接收位置更新：

注册回调（requestLocationUpdates(LocaionRequest, LocationListener)） - 主要用于前景位置跟踪

注册PendingIntent（requestLocationUpdates(LocaionRequest, PendingIntent)） - 用于后台跟踪。通过这种方式，您可以创建一个IntentService，因此Android可以启动此服务以通知您有关新位置的信息。 IntentService有自己的生命周期，不依赖于应用程序生命周期，因此即使关闭/杀死应用程序，也会有位置更新。

如果你想创建一个健身应用程序 - 你肯定想看看ActivityRecognition API

在后台接收GPS位置更新

1 个答案: