我正在Google地图上的两个点之间画一条线。第一个点是我的当前位置，目的地点是经度和纬度从给定地址反向地理编码的位置。
反向地址解析器的代码：
if (Geocoder.isPresent()) {
try {
String location = userLocation;
Geocoder gc = new Geocoder(this);
// get the found Address Objects
List<Address> addresses = gc.getFromLocationName(location, 5);
for (Address a : addresses) {
if (a.hasLatitude() && a.hasLongitude()) {
mLat = a.getLatitude();
mLon = a.getLongitude();
}
}
} catch (IOException e) {
Log.d("eeee", e.toString());
}
}
对于我当前的位置，我已经实现了位置侦听器并重写onLocationChanged方法来获取我的当前位置。
其余逻辑：
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
LatLng myLocation = new LatLng(lat, lon);
mMap.addMarker(new MarkerOptions().position(myLocation).title("Current Location"));
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(myLocation, 16));
LatLng point = new LatLng(mLat, mLon);
// check if there are already two locations
if (markerPoints.size() > 1) {
markerPoints.clear();
mMap.clear();
}
// Adding new item to the ArrayList
markerPoints.add(point);
// Creating MarkerOptions
MarkerOptions options = new MarkerOptions();
// Setting the position of the marker
options.position(point);
/*
For the start location, the color of marker is GREEN and
for the end location, the color of marker is RED.
*/
if (markerPoints.size() == 1) {
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
} else if (markerPoints.size() == 2) {
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}
// Add new marker to the Google Map
mMap.addMarker(options);
// Checks, whether start and end locations are captured
if (markerPoints.size() >= 2) {
LatLng origin = (LatLng) markerPoints.get(0);
LatLng dest = (LatLng) markerPoints.get(1);
// Getting URL to the Google Directions API
String url = this.getUrl(origin, dest);
FetchUrl FetchUrl = new FetchUrl();
// Start downloading json data from Google Directions API
FetchUrl.execute(url);
//move map camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(origin));
mMap.animateCamera(CameraUpdateFactory.zoomTo(11));
}
}
private String getUrl(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";
String mode = "mode=driving";
// Building the parameters to the web service
String parameters = str_origin + "&" + str_dest + "&" + sensor + "&" + mode + "&" +
getResources().getString(R.string.google_maps_key);
// Output format
String output = "json";
// Building the url to the web service
return "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;
}
private class FetchUrl extends AsyncTask<String, Void, String> {
@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) {
Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
return data;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
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));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (Exception e) {
Toast.makeText(this, e.toString(), Toast.LENGTH_SHORT).show();
} finally {
if (iStream != null) {
iStream.close();
}
if (urlConnection != null) {
urlConnection.disconnect();
}
}
return data;
}
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
@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]);
DataParser parser = new DataParser();
// Starts to parse the data
routes = parser.parse(jObject);
} catch (Exception e) {
Toast.makeText(this, e.toString(), Toast.LENGTH_SHORT).show();
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;
PolylineOptions lineOptions = null;
// Traversing through all the routes
for (int i = 0; i < result.size(); i++) {
points = new ArrayList<>();
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);
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(10);
lineOptions.color(Color.RED);
}
// Drawing polyline in the Google Map for the i-th route
if (lineOptions != null) {
mMap.addPolyline(lineOptions);
} else {
Toast.makeText(this, "null", Toast.LENGTH_SHORT).show();
}
}
}
但是它没有给我想要的输出，是否缺少我