sending extra to requestLocationUpdates intentServ

问题:

I'm having trouble sending a string extra with my PendingIntent that I pass to LocationServices.FusedLocationApi.requestLocationUpdates(GoogleApiClient client, LocationRequest request, PendingIntent callbackIntent).

It appears that the username extra i'm putting onto the Intent is mangling the location that requestLocationUpdates is trying to hand off to my IntentService as intent.getParcelableExtra(FusedLocationProviderApi.KEY_LOCATION_CHANGED) returns null.

EDIT

I've tried making a User class that implements Parcelable and putting it as an extra:

mRequestLocationUpdatesIntent.putExtra("username", new User(username));

and I've also tried to put the Parcelable User inside a Bundle as suggested via comment in this bug report https://code.google.com/p/android/issues/detail?id=81812:

Bundle userBundle = new Bundle();
userBundle.putParcelable("user", new User(username));
mRequestLocationUpdatesIntent.putExtra("user", userBundle);

in my service:

Bundle userBundle = intent.getBundleExtra("user");
User user = userBundle.getParcelable("user");
String username = user.getUsername();

However neither of these approaches has made any difference. Whenever I put any extra onto my intent, the location is never added to the intent when the updates occur.

I setup this IntentService to handle location updates:

public class LocationUpdateService extends IntentService {

    private final String TAG = "LocationUpdateService";

    public LocationUpdateService() {
        super("LocationUpdateService");
    }


    @Override
    protected void onHandleIntent(Intent intent) {

        Log.d(TAG, "onHandleIntent");

        Bundle extras = intent.getExtras();
        Log.d(TAG, "keys found inside intent: " + TextUtils.join(", ", extras.keySet()));

        String username = intent.getStringExtra("username");

        if (username != null) {
            Log.d(TAG, "username: " + username);
        } else {
            Log.d(TAG, "username: null");
        }

        if (!intent.hasExtra(FusedLocationProviderApi.KEY_LOCATION_CHANGED)) {
            Log.d(TAG, "intent does not have location :(");
        }

        Location location = intent.getParcelableExtra(FusedLocationProviderApi.KEY_LOCATION_CHANGED);

        if (location == null) {
            Log.d(TAG, "location == null :(");
        }

        Log.d(TAG, "latitude " + String.valueOf(location.getLatitude()));
        Log.d(TAG, "longitude " + String.valueOf(location.getLongitude()));

        ...

    }


}

When the user clicks a button, the startLocationUpdates is called in my main activity:

main activity class:

...

Boolean mLocationUpdatesEnabled = false;

protected void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(LOCATION_UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(LOCATION_UPDATE_FASTEST_INTERVAL);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}

protected void startLocationUpdates() {

    Log.d(TAG, "startng location updates...");

    mLocationUpdatesEnabled = true;

    if (mLocationRequest == null) {
        createLocationRequest();
    }

    // create the Intent to use WebViewActivity to handle results
    Intent mRequestLocationUpdatesIntent = new Intent(this, LocationUpdateService.class);

    // create a PendingIntent
    mRequestLocationUpdatesPendingIntent = PendingIntent.getService(getApplicationContext(), 0,
            mRequestLocationUpdatesIntent,
            PendingIntent.FLAG_CANCEL_CURRENT);

    // request location updates
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
            mLocationRequest,
            mRequestLocationUpdatesPendingIntent);

    Log.d(TAG, "location updates started");
}

protected void stopLocationUpdates() {

    Log.d(TAG, "stopping location updates...");

    mLocationUpdatesEnabled = false;

    LocationServices.FusedLocationApi.removeLocationUpdates(
            mGoogleApiClient,
            mRequestLocationUpdatesPendingIntent);

    Log.d(TAG, "location updates stopped");
}

This all works well and good; When the user presses the button, toggleLocationUpdates is called, which calls LocationServices.FusedLocationApi.requestLocationUpdates which calls my LocationUpdateService where I'm able to get the location.

The trouble comes when I tried to put a string extra onto my Intent using Intent.putExtra(String, String):

main activity class:

...
protected void startLocationUpdates(String username) {
    ....

    // create the Intent to use WebViewActivity to handle results
    Intent mRequestLocationUpdatesIntent = new Intent(this, LocationUpdateService.class);

    //////////////////////////////////////////////////////////////////
    //
    //  When I put this extra, IntentService sees my username extra
    //  but the parcelableExtra `location` == null :(
    // 
    //////////////////////////////////////////////////////////////////

    mRequestLocationUpdatesIntent.putExtra("username", username);
    ...
}
...

EDIT I had started the next sentence as a statement rather than a question: "I am using..."

Am I using the correct approach to sending some extra data to this location update handling IntentService or is there a more-sane way to go about this?

Is this a bug or just poor documentation?

回答1:

Using the IntentService coupled with the FusedLocationProviderAPI will present issues. From the Developer Docs titled Receiving Location Updates:

Depending on the form of the request, the fused location provider either invokes the LocationListener.onLocationChanged() callback method and passes it a Location object, or issues a PendingIntent that contains the location in its extended data. The accuracy and frequency of the updates are affected by the location permissions you've requested and the options you set in the location request object

Further, a PendingIntent is used for extending permissions for another piece of code (FusedLocationProviderAPI in Google Play Services) to execute their code within your apk. An IntentService is used to start a Service defined within the scope of your apk.

So, the method requires an implementation of LocationListener for foreground updates, or a PendingIntent for background updates coupled with a Broadcast Receiver.

This is a working example of some methods used to request location updates from a PendingIntent coupled with extra values.

Note: LocalStorage.java is a utility class for storing local variables, it is not part of the Android API

GPSPlotter

/**
 * Private helper method to initialize the Google Api Client with the
 * LocationServices Api and Build it for use.
 */
private void initializeGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(mContext)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API)
            .build();

}

/**
 * Private helper method to determine whether or not GooglePlayServices
 * are installed on the local system.
 *
 * @return services are installed.
 */
private boolean googlePlayServicesInstalled() {
    int result = GooglePlayServicesUtil.isGooglePlayServicesAvailable(mContext);
    return result == ConnectionResult.SUCCESS;
}

/**
 * Private method to build the Api Client for use with the LocationServices API.
 */
private synchronized void buildApiClient() {
    Log.w(TAG, "Building Google Api Client...");
    initializeGoogleApiClient();
}

/**
 * Private method used to connect the ApiClient to the Api hosted by Google for
 * Accessing Locations.
 */
private void connectClient() {
    mGoogleApiClient.connect();
}

 /**
 * User passes in a requested interval polling time in seconds as an
 * integer.
 *
 * @param theAccount is a reference to the parent activity used for updating views.
 */
public void beginManagedLocationRequests(MyAccount theAccount) {
    if (mAccount == null)
        mAccount = theAccount;

    startBackgroundUpdates();

}

/**
 * Public method to end the managed Location Requests.
 */
public void endManagedLocationRequests() {
        endBackgroundUpdates();

}

/**
 * This method handles the switch in polling rates by stopping and then starting once more the
 * background udpates, which in turn sets the interval in another method in the call stack.
 * @param theInterval the desired interval polling rate
 */
public void changeRequestIntervals(int theInterval) {
    mIntentInterval = theInterval;
    if (LocalStorage.getRequestingBackgroundStatus(mContext)) {
        endBackgroundUpdates();
        startBackgroundUpdates();
    }



}

/**
 * Private helper method to build an Intent that will be couple with a pending intent uses
 * for issuing background Location requests.
 *
 * @return theIntent
 */
private Intent buildBackgroundRequestIntent() {
    Intent intent = new Intent(mContext, BackgroundLocationReceiver.class);
    intent.setAction(BACKGROUND_ACTION);
    intent.putExtra(User.USER_ID, mUserID);
    return intent;
}

/**
 * Private helper method used to generate a PendingIntent for use when the User requests background service
 * within the FusedLocationApi until the Interval is changed.
 *
 * @return pendingIntent
 */
private PendingIntent buildRequestPendingIntent(Intent theIntent) {
    Log.w(TAG, "building pending intent");
    return PendingIntent.getBroadcast(mContext, 0, theIntent, 0);
}


/**
 * Private method to start the Location Updates using the FusedLocation API in the background.
 */
private void startBackgroundUpdates() {
    Log.w(TAG, "Starting background updates");
    if (googlePlayServicesInstalled()) {
        LocalStorage.putBackgroundRequestStatus(true, mContext);
        LocalStorage.putLocationRequestStatus(true, mContext);
        registerAlarmManager();
        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, buildLocationRequest(), buildRequestPendingIntent(buildBackgroundRequestIntent()));
    }
}


/**
 * Private method to end background updates.
 */
private void endBackgroundUpdates() {
    Log.w(TAG, "Ending background updates");
    LocalStorage.putBackgroundRequestStatus(false, mContext);
    LocalStorage.putLocationRequestStatus(false, mContext);
    unregisterAlarmManager();
    LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, buildRequestPendingIntent(buildBackgroundRequestIntent()));
}

BackgroundLocationReceiver

public class BackgroundLocationReceiver extends BroadcastReceiver {
private static final String TAG = "BLocRec: ";
private static final String UPLOAD_ERROR_MESSAGE = "Background Service to Upload Coordinates Failed.";
private static final String UPLOAD_MESSAGE = "Coordinate Batch Pushed to Database.";

public BackgroundLocationReceiver() {
    //Default, no-arg constructor
}

/**
 * This method handles any location updates received when the app is no longer in focus. Coordinates are
 * stored in the local database and uploaded once every hour.
 * @param context the application context
 * @param intent is the pending intent
 */
@Override
public void onReceive(Context context, Intent intent) {

    if (intent.getAction().matches(GPSPlotter.BACKGROUND_ACTION)) {
        Log.w(TAG, "BLR Received-background");
        Location location = intent.getParcelableExtra(FusedLocationProviderApi.KEY_LOCATION_CHANGED);
        storeLocation(location, context, intent.getStringExtra(User.USER_ID));

    }

EDIT The method below builds a LocationRequest necessary for invoking the requestLocationUpdates() method

/**
 * Private helper method used to generate a LocationRequest which will be used to handle all location updates
 * within the FusedLocationApi until the Interval is changed.
 *
 * @return locationRequest
 */
private LocationRequest buildLocationRequest() {
    int dateConversion = 1000;
    LocationRequest locationRequest = LocationRequest.create();
    locationRequest.setInterval(mIntentInterval * dateConversion);
    locationRequest.setFastestInterval((mIntentInterval / 2) * dateConversion);
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    Log.w(TAG, "Building location request");
    return locationRequest;
}

EDIT After a long discussion in chat with Catherine, we came to the conclusion that google play services library 7.5 has a bug that does not process the Parcelable Extra Location passed from FusedLocationProviderAPI when other extras are put into the Intent. However, 7.0 does provide this capability. She said that she will submit a bug and we'll see how long it takes the Android team to resolve