我正在使用谷歌地图开发跟踪Android应用程序。我有以下问题：我的MapFragment中的onLocationChanged方法只被调用一次，然后再也没有。即使我有一个假的GPS提供商正在运行，并经常改变我的位置。位置本身在地图上更新，但该函数仅被调用一次。而且我需要它被调用，因为我想在每个位置变化上绘制路径。
我的代码：
public class MapActivity extends FragmentActivity implements LocationListener,
SensorEventListener{
/* constants */
private static final long INTERVAL = 1000;
private static final float ACCURACY = 20;
public static final int NEW_TRACK_ID = 0;
private GoogleMap map;
private DataSource dataSource;
private SensorManager sensorManager;
private Sensor senAccelerometer;
private boolean zoomEnabled;
private boolean draw;
private Track currentTrack;
private Button saveTrackButton;
private LocationManager locationManager;
private String provider;
private int trackId;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
initialize();
saveTrackButton = (Button) findViewById(R.id.saveTrackButton);
saveTrackButton.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
getDataFromPopupWindow();
}
});
}
private void initialize()
{
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
setUpMapIfNeeded();
startTracking();
dataSource = new DataSource(this);
sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
senAccelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
sensorManager.registerListener(this, senAccelerometer , SensorManager.SENSOR_DELAY_NORMAL);
zoomEnabled = true;
Intent intent = getIntent();
trackId = intent.getIntExtra("trackId", 0);
Toast.makeText(getApplicationContext(), "Track id:" + trackId, Toast.LENGTH_LONG).show();
if(trackId != NEW_TRACK_ID){
currentTrack = getTrackById(trackId);
drawTrack();
draw = false;
}
else{
currentTrack = new Track();
draw = true;
}
}
private void getDataFromPopupWindow()
{
LayoutInflater layoutInflater
= (LayoutInflater)getBaseContext()
.getSystemService(LAYOUT_INFLATER_SERVICE);
View popupView = layoutInflater.inflate(R.layout.save_track_window, null);
final PopupWindow popupWindow = new PopupWindow(
popupView,
LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT);
final EditText editName = (EditText) popupView.findViewById (R.id.trackName);
editName.requestFocus();
Button btnDismiss = (Button)popupView.findViewById(R.id.cancel);
btnDismiss.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
popupWindow.dismiss();
}
});
Button btnSave = (Button) popupView.findViewById(R.id.save);
btnSave.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String trackName = editName.getText().toString();
saveTrack(trackName);
popupWindow.dismiss();
}
});
popupWindow.setFocusable(true);
popupWindow.update();
popupWindow.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
popupWindow.showAtLocation(saveTrackButton, Gravity.CENTER, 0, -100);
}
/**
* Saves the track to database when finished
*/
private void saveTrack(String trackName){
Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = c.get(Calendar.DAY_OF_MONTH);
String date = String.valueOf(year) + "-" + String.valueOf(month) + "-" + String.valueOf(day) ;
currentTrack.setDate(date);
currentTrack.setName(trackName);
dataSource.open();
dataSource.insertTrack(currentTrack);
dataSource.close();
}
/**
* Centers the view of the map around the current user's location.
* @param loc LatLng object representing user's current coordinates.
*/
private void zoom (LatLng loc)
{
if(zoomEnabled)
{
map.animateCamera(CameraUpdateFactory.newLatLngZoom(loc, 16));
zoomEnabled = false;
}
}
/** Initializes the GoogleMap object if it hasn't been already done.
* If successful, enables location tracking.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (map == null) {
// Try to obtain the map from the SupportMapFragment.
map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
.getMap();
map.setMyLocationEnabled(true);
// Check if we were successful in obtaining the map.
if (map != null) {
startTracking();
}
}
}
private void startTracking()
{
locationManager.requestLocationUpdates(provider, INTERVAL, ACCURACY, this);
}
private Track getTrackById (int trackId)
{
dataSource.open();
Track track = dataSource.getTrack(trackId);
dataSource.close();
return track;
}
private void drawTrack()
{
Toast.makeText(this, currentTrack.getPoints().toString(), Toast.LENGTH_SHORT).show();
map.addPolyline(new PolylineOptions().addAll(currentTrack.getPoints()).width(5).color(Color.BLUE));
}
@Override
protected void onPause() {
super.onPause();
dataSource.close();
locationManager.removeUpdates(this);
}
@Override
protected void onResume() {
super.onResume();
dataSource.open();
setUpMapIfNeeded();
}
@Override
public void onAccuracyChanged(Sensor arg0, int arg1) {
// TODO Auto-generated method stub
}
@Override
public void onSensorChanged(SensorEvent event) {
Sensor mySensor = event.sensor;
if (mySensor.getType() == Sensor.TYPE_ACCELEROMETER) {
if(event.values[0] > 18 || event.values[1] > 18 || event.values[2] > 18 && map.getMyLocation()!=null)
{
Intent intent = new Intent(this, CameraActivity.class);
intent.putExtra("latitude", map.getMyLocation().getLatitude());
intent.putExtra("longitude", map.getMyLocation().getLongitude());
intent.putExtra("trackId", trackId);
startActivity(intent);
}
}
}
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
LatLng loc = new LatLng(location.getLatitude(), location.getLongitude());
currentTrack.addPoint(loc);
if(draw) drawTrack();
Toast.makeText(this, "location changed", Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
Toast.makeText(this, "Enabled new provider " + provider,
Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
Toast.makeText(this, "Disabled provider " + provider,
Toast.LENGTH_SHORT).show();
}
}
有什么想法吗？
答案 0 :(得分：0)
错误可能与onLocationRequest方法中的timeMin参数有关。
答案 1 :(得分：0)
该问题仅涉及requestLocationUpdate方法参数（minTime参数设置为错误的值）。问题解决了。