我正在尝试使用Google地图实现一个简单的导航应用。最初，我开发了一个代码，用于在地图上标记两个地理点并显示它们之间的路线。 现在我正在尝试根据用户位置将第一个标记移向第二个标记（目标）。
为此，我使用了LocationListener并在onLocationChanged中实现了代码。
问题是onLocationChanged没有被触发，并且标记没有根据用户位置移动。
这是我的代码。
MapActivity.java
public class MapActivity extends FragmentActivity implements OnMapClickListener, LocationListener{
private GoogleMap gMap;
private ArrayList<LatLng> markersArray; //Marker points ArrayList
private ArrayList<Marker> markers;
private MarkerOptions options; //Marker options
String distance="";
String duration="";
private TextView travelDetails;
private ProgressDialog pDialog;
private double lattitude=0.0;
private double longitude=0.0;
Marker mMarker;
String bestAvailableProvider;
private LocationManager mLocationManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
//Loading Google Maps
try{
loadMapView();
markersArray=new ArrayList<LatLng>();
markers=new ArrayList<Marker>();
gMap.setOnMapClickListener(this);
gMap.setMyLocationEnabled(true);
gMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
travelDetails=(TextView) findViewById(R.id.lbl_traveldetails);
pDialog=new ProgressDialog(MapActivity.this);
}catch(Exception e){
e.printStackTrace();
}
}
/*
* This method loads map
*
*/
private void loadMapView(){
if (gMap==null) {
gMap=((SupportMapFragment)getSupportFragmentManager()
.findFragmentById(R.id.map_fragment)).getMap();
}
mLocationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
// Specify Location Provider criteria
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setSpeedRequired(false);
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0,this);
}
/*
* catches onclick event of map
* @see com.google.android.gms.maps.GoogleMap.OnMapClickListener#onMapClick(com.google.android.gms.maps.model.LatLng)
*/
@Override
public void onMapClick(LatLng point) {
//Clearing markers in map
if (markersArray.size()>1) {
markersArray.clear();
gMap.clear();
}
//Adding marker to array
markersArray.add(point);
//marking point on Map
addMarkerOnMap(point);
//Drawing route when two markers are placed
if(markersArray.size() >= 2){
LatLng origin = markersArray.get(0);
LatLng dest = markersArray.get(1);
String url = getDirectionsUrl(origin, dest);
DownloadTask downloadTask = new DownloadTask();
downloadTask.execute(url);
}
}
/*
* This method places markers on map
*/
private void addMarkerOnMap(LatLng point){
//Marking points on map
options=new MarkerOptions();
options.position(point);
//Setting marker icons
if (markersArray.size()==1) {
//Source marker point
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
}else if(markersArray.size()==2){
//Destination marker point
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}
//adding marker point to map
try{
Marker mMarker=gMap.addMarker(options);
markers.add(mMarker);
}catch(Exception e){
e.printStackTrace();
}
}
/*
* Getting direction url between two points
*
*/
private String getDirectionsUrl(LatLng origin,LatLng dest){
// Origin of route
String str_origin = "origin="+origin.latitude+","+origin.longitude;
// Destination of route
String str_dest = "destination="+dest.latitude+","+dest.longitude;
// Sensor enabled
String sensor = "sensor=false";
// Building the parameters to the web service
String parameters = str_origin+"&"+str_dest+"&"+sensor;
// Output format
String output = "json";
String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;
return url;
}
/*
* passing the direction url
*
*/
private class DownloadTask extends AsyncTask<String, Void, String>{
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog.show();
pDialog.setMessage("Loading route...");
pDialog.setCancelable(false);
}
// Downloading data in non-ui thread
@Override
protected String doInBackground(String... url) {
// For storing data from web service
String data = "";
try{
// Fetching the data from web service
data = downloadUrl(url[0]);
}catch(Exception e){
Log.d("Background Task",e.toString());
}
return data;
}
// Executes in UI thread, after the execution of
// doInBackground()
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
/*
* downloading from url
*
*/
private String downloadUrl(String strUrl) throws IOException{
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try{
URL url = new URL(strUrl);
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while( ( line = br.readLine()) != null){
sb.append(line);
}
data = sb.toString();
br.close();
}catch(Exception e){
Log.d("Exception while downloading url", e.toString());
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>>>{
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try{
jObject = new JSONObject(jsonData[0]);
DirectionsJsonParser parser = new DirectionsJsonParser();
// Starts parsing data
routes = parser.parse(jObject);
}catch(Exception e){
e.printStackTrace();
}
return routes;
}
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points = null;
PolylineOptions lineOptions = null;
// MarkerOptions markerOptions = new MarkerOptions();
// Traversing through all the routes
for(int i=0;i<result.size();i++){
points = new ArrayList<LatLng>();
lineOptions = new PolylineOptions();
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
// Fetching all the points in i-th route
for(int j=0;j<path.size();j++){
HashMap<String,String> point = path.get(j);
if(j==0){ // Get distance from the list
distance = (String)point.get("distance");
continue;
}else if(j==1){ // Get duration from the list
duration = (String)point.get("duration");
continue;
}
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
// Adding all the points in the route to LineOptions
lineOptions.addAll(points);
lineOptions.width(5);
lineOptions.color(Color.BLUE);
}
// Drawing polyline in the Google Map for the i-th route
try{
gMap.addPolyline(lineOptions);
travelDetails.setText("Distance:"+distance+"Duration:"+duration);
pDialog.dismiss();
}catch (Exception e) {
if (pDialog.isShowing()) {
pDialog.dismiss();
}
Toast.makeText(getApplicationContext(), "No Road route found.", Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
}
@Override
protected void onResume() {
super.onResume();
loadMapView();
}
@Override
protected void onPause() {
super.onPause();
mLocationManager.removeUpdates(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.map, menu);
return true;
}
/*
* (non-Javadoc)
* @see com.google.android.gms.maps.LocationSource.OnLocationChangedListener#onLocationChanged(android.location.Location)
*/
@Override
public void onLocationChanged(Location location) {
Log.e("loca", ""+location.getLatitude());
try {
if(markersArray.size()>0){
lattitude=location.getLatitude();
longitude=location.getLongitude();
LatLng mLatLng=new LatLng(lattitude, longitude);
Marker newMarker=markers.get(0);
newMarker.setPosition(mLatLng);
gMap.animateCamera(CameraUpdateFactory.newLatLng(mLatLng));
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
DirectionsJsonParser.java
public class DirectionsJsonParser {
public List<List<HashMap<String,String>>> parse(JSONObject jObject){
List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ;
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONArray jSteps = null;
JSONObject jDistance = null;
JSONObject jDuration = null;
try {
jRoutes = jObject.getJSONArray("routes");
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<HashMap<String, String>>();
for(int j=0;j<jLegs.length();j++){
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Getting distance from the json data */
jDistance = ((JSONObject) jLegs.get(j)).getJSONObject("distance");
HashMap<String, String> hmDistance = new HashMap<String, String>();
hmDistance.put("distance", jDistance.getString("text"));
/** Getting duration from the json data */
jDuration = ((JSONObject) jLegs.get(j)).getJSONObject("duration");
HashMap<String, String> hmDuration = new HashMap<String, String>();
hmDuration.put("duration", jDuration.getString("text"));
/** Adding distance object to the path */
path.add(hmDistance);
/** Adding duration object to the path */
path.add(hmDuration);
/** Getting poly points */
for(int k=0;k<jSteps.length();k++){
String polyline = "";
polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points");
List<LatLng> list = decodePoly(polyline);
for(int l=0;l<list.size();l++){
HashMap<String, String> hm = new HashMap<String, String>();
hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude) );
hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude) );
path.add(hm);
}
}
/** Adding poly points */
routes.add(path);
}
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception e){
}
return routes;
}
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
}
答案 0 :(得分：0)
我认为您还没有使用过地址提供商，请使用googleapiclient
并阅读有关此主题的信息，它可让您在地点更改时显示地图上的当前位置，从而为您提供当前位置。
实现GoogleApiClient.ConnectionCallbacks，GoogleApiClient.OnConnectionFailedListener 在你的活动中，你可以很容易地做到这一点。