在自定义列表器服务中使用 ActivityContext

Question

PrimaryDashBoard，我在其中使用LocatinListener并从服务中检索位置

public class PrimaryDashboard extends AppCompatActivity implements LocationListener {
public LatLng myLatLng=new LatLng(0.0,0.0);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_primary_dashboard);
try {
Intent i = new Intent(this, LocationManager.class);
startService(i);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onLocationChanged(Location location) {
myLatLng=new LatLng(location.getLatitude(),location.getLongitude());
}
@Override
public void GPSDisabled(String errorMessage) {
}
@Override
public void GPSEnabled() {
}
}

这是位置列表

public interface LocationListener {
public void onLocationChanged(Location location);
public  void GPSDisabled(String errorMessage);
public void GPSEnabled();
}

这是我的服务，我想在其中启动位置列表器，并希望从列表器更新位置值

public class LocationManager extends IntentService {
private static final String TAG = LocationManager.class.getSimpleName();
// Registered callbacks
public LocationListener locationUpdate;
public static final int REQUEST_CHECK_SETTINGS = 0x1;
private static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;
private static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS =
UPDATE_INTERVAL_IN_MILLISECONDS / 2;
private FusedLocationProviderClient mFusedLocationClient;
private SettingsClient mSettingsClient;
private LocationRequest mLocationRequest;
private LocationSettingsRequest mLocationSettingsRequest;
private LocationCallback mLocationCallback;
private Location mCurrentLocation;
private Boolean mRequestingLocationUpdates = false;
@SuppressLint("ServiceCast")
@Override
public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
this.locationUpdate = (LocationListener)  getApplicationContext();
mRequestingLocationUpdates = false;
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(getApplicationContext());
mSettingsClient = LocationServices.getSettingsClient(getApplicationContext());
createLocationCallback();
createLocationRequest();
buildLocationSettingsRequest();
if (!mRequestingLocationUpdates) {
mRequestingLocationUpdates = true;
startLocationUpdates();
}
return START_STICKY;
}
@Override
protected void onHandleIntent(@Nullable Intent intent) {
}
@SuppressLint("ServiceCast")
@Override
public void onCreate() {
super.onCreate();
}
public LocationManager() {
super("locationManager");
}
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);
}
/**
* Creates a callback for receiving location events.
*/
private void createLocationCallback() {
mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
super.onLocationResult(locationResult);
mCurrentLocation = locationResult.getLastLocation();
PrefManager.getInstance(getApplicationContext()).setLastLatLng(Double.valueOf(locationResult.getLastLocation().getLatitude()), Double.valueOf(locationResult.getLastLocation().getLongitude()));
if (locationUpdate != null)
locationUpdate.onLocationChanged(locationResult.getLastLocation());
}
};
}

private void buildLocationSettingsRequest() {
LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
builder.addLocationRequest(mLocationRequest);
mLocationSettingsRequest = builder.build();
}

private void startLocationUpdates() {
// Begin by checking if the device has the necessary location settings.
mSettingsClient.checkLocationSettings(mLocationSettingsRequest)
.addOnSuccessListener(new OnSuccessListener<LocationSettingsResponse>() {
@SuppressLint("MissingPermission")
@Override
public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
LogCat.show("All location settings are satisfied.");
if (locationUpdate != null)
locationUpdate.GPSEnabled();
mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
int statusCode = ((ApiException) e).getStatusCode();
switch (statusCode) {
case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
if (locationUpdate != null)
locationUpdate.GPSDisabled("Location settings are not satisfied. Attempting to upgrade location settings ");
LogCat.show("Location settings are not satisfied. Attempting to upgrade location settings ");
try {
// Show the dialog by calling startResolutionForResult(), and check the
// result in onActivityResult().
ResolvableApiException rae = (ResolvableApiException) e;
rae.startResolutionForResult((Activity) getApplicationContext(), REQUEST_CHECK_SETTINGS);
} catch (IntentSender.SendIntentException sie) {
Log.i(TAG, "PendingIntent unable to execute request.");
}
break;
case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
String errorMessage = "Location settings are inadequate, and cannot be " +
"fixed here. Fix in Settings.";
LogCat.show(errorMessage);
if (locationUpdate != null)
locationUpdate.GPSDisabled(errorMessage);
Toast.makeText(getApplicationContext(), errorMessage, Toast.LENGTH_LONG).show();
mRequestingLocationUpdates = false;
}

}
});
}

}

这行代码给我带来了一个问题，因为它需要活动上下文，当它不是服务并且我传递活动上下文时，它工作得很好。

this.locationUpdate = (LocationListener( getApplicationContext((;

Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to driver.com.driver.LocationComponents.LocationListener
java.lang.RuntimeException: Unable to create service driver.com.driver.LocationComponents.LocationManager: java.lang.ClassCastException: android.app.Application cannot be cast to driver.com.driver.LocationComponents.LocationListener

Answer 1

首先，您的应用程序类没有实现LocationListener接口，因此您会收到此错误。 您无法在意向服务中获取活动实例，因为 1( 它可能不再处于活动状态 2( 意图服务可以从其他服务或广播接收器启动。为了将LocationListener方法与您的活动进行通信，您需要使用本地广播管理器。