我遇到的问题是，有时未显示连接Google地图上2个点的路径。但不是永远，有时也会出现。我该怎么办？ 这是我在android中的代码
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";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;
return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
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){
Toast.makeText(MainActivity.this,
"Exception while downloading url",
Toast.LENGTH_LONG).show();
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, String> {
// 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);
}
}
/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{
// Parsing the data in non-ui thread
@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;
}
// Executes in UI thread, after the parsing process
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points = new ArrayList<LatLng>();;
PolylineOptions lineOptions = new PolylineOptions();;
lineOptions.width(8);
lineOptions.color(Color.GREEN);
MarkerOptions markerOptions = new MarkerOptions();
// Traversing through all the routes
for(int i=0;i<result.size();i++){
// 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);
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);
}
// Drawing polyline in the Google Map for the i-th route
if(points.size()!=0)googleMap.addPolyline(lineOptions);//to avoid crash
}
}
如何解决以上问题？请帮我。 还是访问延迟的服务器出现问题？
答案 0 :(得分：0)
如果使用经度获取当前位置，则请实施此方法。它将在每次onLocationChanged时为您提供。
@SuppressLint({"ClickableViewAccessibility"})
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Start implementation for getting current location
callTrackLocation();
}
@SuppressLint("MissingPermission")
private void callTrackLocation() {
if (latitude != 0.0 && longitude != 0.0 && !country.equalsIgnoreCase("")) {
loc_func();
}
LocationListener locationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
longitude = location.getLongitude();
latitude = location.getLatitude();
Log.d("Location : ", location.toString());
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
};
if (Build.VERSION.SDK_INT < 23) {
if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
Log.i(TAG, "onViewCreated: location manager in if condition");
}
} else {
if (ActivityCompat.checkSelfPermission(Objects.requireNonNull(getActivity()), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
return;
} else {
if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
Log.i(TAG, "onViewCreated: location manager in else if condition");
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}
Location location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
longitude = location.getLongitude();
latitude = location.getLatitude();
}
if (latitude != 0.0 && longitude != 0.0) {
loc_func();
}
}
public void loc_func() {
Log.i(TAG, "latitude: " + latitude + " longitude : " + longitude);
Geocoder geocoder = new Geocoder(getActivity());
List<Address> addresses = null;
try {
addresses = geocoder.getFromLocation(latitude, longitude, 1);
if (addresses != null) {
Log.i(TAG, "latitude: " + latitude + " longitude : " + longitude + " loc_func : " + addresses.get(0).getCountryName());
country = addresses.get(0).getCountryName();
String state = addresses.get(0).getAdminArea();
String city = addresses.get(0).getLocality();
}
// GetAllQuestionByUser();
Log.e(TAG, "loc_func: Country : " + country);
} catch (IOException e) {
e.printStackTrace();
}
}