blackberry location-based services

问题

Can anyone please inform me how to work with blackberry location-based services? i am working on a project for a blackberry mobile application. i never had a blackberry before and i dont have a contract with any provider (just have a sim card from 3 and mobile device 9000 OS 4.6).

In the project i am currently trying to use the following code in order to retrieve the coordinates of current location (startpoint) and destination location (endpoint). It works just fine on the simulator but on the device nothing. Should i have a contract with a provider or something? and does this need just GPS or internet, or both to work?

Code:

String destination = "London";

final Landmark[] landmarks = Locator.geocode(destination.replace('\n', ' '), null);
Coordinates endPoint = landmarks[0].getQualifiedCoordinates();
// Get a location provider.
LocationProvider provider = LocationProvider.getInstance(null);
if (provider == null)
{
    throw new IllegalStateException("No LocationProvider Available!!");
}
// Try to fetch the current location and get the coordinates of the current location.
Coordinates startPoint = provider.getLocation(-1).getQualifiedCoordinates();

double destiinationlatitude = endPoint.getLatitude();
double currentlatitude = startPoint.getLatitude();

thank you in advance

回答1:

To get the GPS location on any version prior to 5.0 you have to instantiate this things

Criteria
Location Provider
Location Object (done with the location provider)

Here's the things you instantiate:

Criteria criteria = null;
LocationProvider provider = null;
javax.microedition.location.Location location = null;

After that you must assign values to the Criteria, get the instance of the LocationProvider using the criteria and get the Location using the LocationProvider.

criteria = new Criteria();
criteria.setPreferredPowerConsumption(Criteria.POWER_USAGE_HIGH);
criteria.setHorizontalAccuracy(50);
criteria.setVerticalAccuracy(50);
criteria.setCostAllowed(true);
provider = LocationProvider.getInstance(criteria);
location = provider.getLocation(5);

Note that the Criteria will determine if you use GPS, Wifi assisted location or Cellsite location, more info on the criteria setting here: http://www.blackberry.com/developers/docs/4.5.0api/javax/microedition/location/Criteria.html

After that, to get the coordinates you call the method: location.getQualifiedCoordinates()

And that's that... you should call this from a separate thread. And also the actual location management code should be on a try-catch block but the IDE will help you with that.

回答2:

in this code we are seeing which modes are available to get co-ordinates(I.E if phone does not have a GPS then it should use satalite info.)

The Lat and Long is being retreived by the available mode.

A mapview is created (MapView which is the map, You set the required specifications such as the zooming, lat, lon, etc )then you invoke the map and the set zoom, lat, lon , etc will be applied to the map that reflects onto the screen.

CustomMapField mMapField;
Coordinates mCoordinates;
BlackBerryCriteria blackBerryCriteria = null;
BlackBerryLocation blackBerryLocation = null;
BlackBerryLocationProvider blackBerryLocationProvider = null;
double Doublelat = 0.0;
double Doublelng = 0.0;
blackBerryCriteria = new BlackBerryCriteria();
if(GPSInfo.isGPSModeAvailable(GPSInfo.GPS_MODE_CELLSITE)){
  blackBerryCriteria.setMode(GPSInfo.GPS_MODE_CELLSITE);
}else if(GPSInfo.isGPSModeAvailable(GPSInfo.GPS_MODE_ASSIST)){
  blackBerryCriteria.setMode(GPSInfo.GPS_MODE_ASSIST);
}else if(GPSInfo.isGPSModeAvailable(GPSInfo.GPS_MODE_AUTONOMOUS)){
  blackBerryCriteria.setMode(GPSInfo.GPS_MODE_AUTONOMOUS);
}else{
   blackBerryCriteria.setCostAllowed(true);
   blackBerryCriteria.setPreferredPowerConsumption(Criteria.POWER_USAGE_LOW);
} try {
   blackBerryLocationProvider = (BlackBerryLocationProvider)          BlackBerryLocationProvider.getInstance(blackBerryCriteria);
   blackBerryLocation = (BlackBerryLocation) blackBerryLocationProvider.getLocation(60);
   QualifiedCoordinates qualifiedCoordinates = blackBerryLocation.getQualifiedCoordinates();
   Doublelat = qualifiedCoordinates.getLatitude();
   Doublelng = qualifiedCoordinates.getLongitude();
   mCoordinates = new  Coordinates(Doublelat, Doublelng, 0);
   MapView mapView = new MapView();
   mapView.setLatitude(finalintlat);
   mapView.setLongitude(finalintlng);
   mapView.setZoom(10);
   MapsArguments mapsArgs = new MapsArguments(mapView);
   Invoke.invokeApplication(Invoke.APP_TYPE_MAPS, mapsArgs);
}catch(Exception e){
   System.out.println("Error in location :"+e.toString());
   System.out.println("Error in location :"+e.getMessage());
}

来源：https://stackoverflow.com/questions/6906409/blackberry-location-based-services

标签

blackberry