我想根据我的 Android 应用程序中的可用路线，在源和目的地之间的 Google 地图中添加一些检查点（标记）。
【问题讨论】：
标签： android google-maps android-layout android-maps-v2
查看此 Google 地图教程HERE。
在第 4 步中，您解析一个包含不同路由的 JSON。从每条路线中，您可以获得具有 Lat 和 Lng 值的点。
【讨论】：
public class PathToDestination {
private GoogleMap mMap;
private Context context;
private static final String API_KEY = "your key";
private String pathColor = "#05b1fb";//default blue color
private int pathWidth = 5;//default is 5
private Polyline line;
private PolylineOptions polylineOptions;
public PathToDestination(Context context, GoogleMap mMap) {
this.context = context;
this.mMap = mMap;
}
public void setPathColor(String pathColor) {
this.pathColor = pathColor;
}
public void setPathWidth(int pathWidth) {
this.pathWidth = pathWidth;
}
public void drawPathBetween(@MapManager.PathMode int mode, double sourcelat, double sourcelog, double destlat, double destlog) {
drawPathBetween(mode, sourcelat, sourcelog, destlat, destlog, null);
}
public void drawPathBetween(@MapManager.PathMode int mode, double sourcelat, double sourcelog, double destlat, double destlog, MapModel[] waypoints) {
String urlStr = makeURL(mode, sourcelat, sourcelog, destlat, destlog, waypoints);
new ConnectAsyncTask(urlStr).execute();
}
/*private String makeURL(double sourcelat, double sourcelog, double destlat, double destlog) {
return makeURL(sourcelat, sourcelog, destlat, destlog, );
}*/
private String makeURL(@MapManager.PathMode int mode, double sourcelat, double sourcelog, double destlat, double destlog, MapModel... waypoints) {
StringBuilder urlString = new StringBuilder();
urlString.append("https://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append(Double.toString(sourcelat));
urlString.append(",");
urlString.append(Double.toString(sourcelog));
if (waypoints != null && waypoints.length > 0) {
urlString.append("&waypoints=");// waypoints
for (int i = 0; i < waypoints.length; i++) {
MapModel coordinate = waypoints[i];
urlString.append(coordinate.getLatitude());
urlString.append(",");
urlString.append(coordinate.getLongitude());
if (i < waypoints.length - 1) {
urlString.append("|");
}
}
}
urlString.append("&destination=");// to
urlString.append(Double.toString(destlat));
urlString.append(",");
urlString.append(Double.toString(destlog));
urlString.append("&sensor=false");
urlString.append("&mode=" + mode);
urlString.append("&alternatives=true");
urlString.append("&key=" + API_KEY);
return urlString.toString();
}
private void drawPath(String result) {
try {
//Tranform the string into a json object
final JSONObject json = new JSONObject(result);
JSONArray routeArray = json.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<LatLng> list = null;
if (polylineOptions == null) {
polylineOptions = new PolylineOptions()
.width(pathWidth)
.color(Color.parseColor(pathColor)) //Google maps blue color
.geodesic(true);
}
list = decodePoly(encodedString);
polylineOptions.addAll(list);
if (line == null) {
line = mMap.addPolyline(polylineOptions);
}
line.setPoints(list);
/*
for(int z = 0; z<list.size()-1;z++){
LatLng src= list.get(z);
LatLng dest= list.get(z+1);
Polyline line = mMap.addPolyline(new PolylineOptions()
.add(new LatLng(src.latitude, src.longitude), new LatLng(dest.latitude, dest.longitude))
.width(2)
.color(Color.BLUE).geodesic(true));
}
*/
} catch (JSONException e) {
e.printStackTrace();
}
}
public void drawPathFromEncodedPolyline(String encodedPolyline) {
// try {
//Tranform the string into a json object
// final JSONObject json = new JSONObject(result);
// JSONArray routeArray = json.getJSONArray("routes");
// JSONObject routes = routeArray.getJSONObject(0);
// JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
// String encodedString = overviewPolylines.getString("points");
List<LatLng> list = decodePoly(encodedPolyline);
Polyline line = mMap.addPolyline(new PolylineOptions()
.addAll(list)
.width(5)
.color(Color.parseColor("#05b1fb"))//Google maps blue color
.geodesic(true)
);
/*
for(int z = 0; z<list.size()-1;z++){
LatLng src= list.get(z);
LatLng dest= list.get(z+1);
Polyline line = mMap.addPolyline(new PolylineOptions()
.add(new LatLng(src.latitude, src.longitude), new LatLng(dest.latitude, dest.longitude))
.width(2)
.color(Color.BLUE).geodesic(true));
}
*/
// } catch (JSONException e) {
// e.printStackTrace();
// }
}
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;
}
private class ConnectAsyncTask extends AsyncTask<Void, Void, String> {
private ProgressDialog progressDialog;
String url;
ConnectAsyncTask(String urlPass) {
url = urlPass;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
if ((Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 &&
!((Activity) context).isDestroyed()) ||
!((Activity) context).isFinishing()) {
progressDialog = new ProgressDialog(context);
// progressDialog.setMessage("Fetching route, Please wait...");
// progressDialog.setIndeterminate(true);
// progressDialog.show();
}
}
@Override
protected String doInBackground(Void... params) {
HttpURLConnection conn = null;
StringBuilder jsonResults = new StringBuilder();
try {
URL url = new URL(this.url);
conn = (HttpURLConnection) url.openConnection();
InputStreamReader in = new InputStreamReader(conn.getInputStream());
// Load the results into a StringBuilder
int read;
char[] buff = new char[1024];
while ((read = in.read(buff)) != -1) {
jsonResults.append(buff, 0, read);
}
} catch (MalformedURLException e) {
return jsonResults.toString();
} catch (IOException e) {
return jsonResults.toString();
} finally {
if (conn != null) {
conn.disconnect();
}
}
return jsonResults.toString();
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (progressDialog != null) {
progressDialog.hide();
}
if (result != null) {
drawPath(result);
}
}
}
public void clearRoute() {
if (line != null) {
line.remove();
}
line = null;
polylineOptions = null;
}
}
这里 MapModel 是一个接口
public interface MapModel {
double getLatitude();
double getLongitude();
}
如果你想要 LatLng 列表，你可以很容易地从
drawPathFromEncodedPolyline(String encodedPolyline) 方法。
您可以查看here 以了解其他地图功能。
【讨论】：