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我在获取当前用户位置时遇到问题。代码起初可以工作，但一段时间后它会停止显示当前位置。我尝试了几种方法来解决这个问题，但结果相同。

这是我的代码：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mapscreen);
    
    mapView = (MapView) findViewById(R.id.mapView);
    mapController = mapView.getController();
    

    
    
    String provider = getProvider();
    
    LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
    
    //getLastKnownPoint();
    locationManager.requestLocationUpdates(provider, 0, 0, locationListener);
    drawCurrPositionOverlay();
    
    
}


private LocationListener locationListener = new LocationListener() {
    
    
    @Override
    public void onLocationChanged(Location location) {
        GeoPoint currentPoint = getCurrentPoint(location);
        animateToCurrentPoint(currentPoint);
        currentLocation = location;
        currentGeoPoint = currentPoint;
        
    }
    
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub
        
    }
    
    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub
        
    }
    
    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub
        
    }
    
    
};

public GeoPoint getCurrentPoint (Location location){
    GeoPoint currentPoint = new GeoPoint((int)(location.getLatitude()*1E6),(int)(location.getLongitude()*1E6));
    return currentPoint;
    
}

public GeoPoint getLastKnownPoint (){
    
    GeoPoint lastKnownPoint = null;
    Location lastKnownLocation = locationManager.getLastKnownLocation(getProvider());
    if(lastKnownLocation != null){
         lastKnownPoint = getCurrentPoint(lastKnownLocation);
    }
    
    return lastKnownPoint;
}

public void animateToCurrentPoint(GeoPoint currentPoint){
    
    mapController.animateTo(currentPoint);
    mapController.setCenter(currentPoint);
    mapController.setZoom(15);
}


public void drawCurrPositionOverlay(){
    List<Overlay> overlays = mapView.getOverlays();
    CustomItemizedOverlay<CustomOverlayItem> itemizedOverlay;
    overlays.remove(currPos);
    Drawable marker = getResources().getDrawable(R.drawable.me);
    currPos = new MapOverlay(marker,mapView);
    GeoPoint drawMyPoint = null;
    
    if(currentGeoPoint==null){
        drawMyPoint = getLastKnownPoint();
    }
    
   else {
        
       drawMyPoint = currentGeoPoint;
   }
    
    OverlayItem overlayitem = new OverlayItem(drawMyPoint, "I'm here ", "wee");
    currPos.addOverlay(overlayitem);
    overlays.add(currPos);
    currPos.setCurrentLocation(currentLocation);
    
    
    
    
}

public String getProvider() {
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    criteria.setPowerRequirement(Criteria.NO_REQUIREMENT);
    criteria.setAccuracy(Criteria.NO_REQUIREMENT);
    String Provider = locationManager.getBestProvider(criteria, true);
    return Provider;
}




@Override
protected boolean isRouteDisplayed() {
    // TODO Auto-generated method stub
    return false;
}

@Override
protected void onResume() {
    super.onResume();
    locationManager.requestLocationUpdates(getProvider(), 100, 1, locationListener);
  
}
 
@Override
protected void onPause() {
    super.onPause();
  locationManager.removeUpdates(locationListener);
   
}

}

而且我还遇到了drawCurrPosition（当代码“工作”时）功能（使用自定义气球）的问题，方法将标记放在最后一个已知位置，而不是我当前的位置（所以标记总是后退一步）。功能仅在打开的应用程序上将标记放在当前位置。

请你能帮助我，因为我看不出我的代码有什么问题

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2 回答 2

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drawCurrPositionOverlay()被调用，onCreate()实际上应该只是在onLocationChanged(). 这样，您的叠加层将始终使用当前位置进行更新，而不是仅包含第一个位置。

于 2012-03-22T01:28:11.873 回答
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1）制作类gps跟踪器 

    public class GPSTracker extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude

// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;

public GPSTracker(Context context) {
    this.mContext = context;
    getLocation();
}

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */
public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(GPSTracker.this);
    }       
}

/**
 * Function to get latitude
 * */
public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */
public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
        dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location location) {
}

@Override
public void onProviderDisabled(String provider) {
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

@Override
public IBinder onBind(Intent arg0) {
    return null;
}

}

2）在活动中使用代码获取位置

   GPSTracker gps = new GPSTracker(TwitterComposeActivity.this);

        // check if GPS enabled
        if (gps.canGetLocation()) {

            latitude = gps.getLatitude();
            longitude = gps.getLongitude();


        } else {

            gps.showSettingsAlert();
        }
于 2012-10-25T13:41:50.603 回答