注意：抱歉我的英语不好，因为英语不是我的母语，我为此使用了谷歌翻译。
我正在开发一个 Android 地图应用程序，用户可以在其中找到朋友的当前位置。为了存储当前位置，我使用 Firebase 实时数据库。在 Lalit Singh 之前的帮助下，它现在可以显示时间和距离，但仍然没有更新两个不同地点之间的折线。我的更新代码如下。
mapsActivity.java（我从火力基地获取朋友位置并调用更新的时间、距离和折线方法）
public void proceed(final View view) {
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Email");
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
UserInformation details = dataSnapshot1.getValue(UserInformation.class);
if (mMap != null) {
mMap.clear();
}
MarkerOptions markerOptions = new MarkerOptions();
LatLng latLng1 = new LatLng(details.getLatitude(), details.getLongitude());
markerOptions.position(latLng1);
markerOptions.title(String.valueOf(latLng1));
mMap.addMarker(markerOptions).setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng1));
mMap.animateCamera(CameraUpdateFactory.zoomTo(14));
distance_task.getDirectionsUrl(latLng1, markerOptions.getPosition());
distance_task.setLoadListener(new CalculateDistanceTime.taskCompleteListener() {
@Override
public void taskCompleted(String[] time_distance) {
text1.setText(time_distance[0]); //Distance
text2.setText(time_distance[1]); //Time
}
});
String url = getDirectionsUrl(latLng1, markerOptions.getPosition());
DownloadTask downloadTask = new DownloadTask();
downloadTask.execute(url);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
CalculateDistanceTime.java（添加了新类）
class CalculateDistanceTime { private taskCompleteListener
mTaskListener; private Context mContext;
CalculateDistanceTime(Context context) {
mContext = context; } void setLoadListener(taskCompleteListener taskListener) {
mTaskListener = taskListener; } void 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;
DownloadTask downloadTask = new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url); }
private String downloadUrl(String strUrl) throws IOException {
String data = "";
HttpURLConnection urlConnection;
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
try (InputStream 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) {
Log.d("Excp. while downloading", e.toString());
} finally {
urlConnection.disconnect();
}
return data; }
interface taskCompleteListener {
void taskCompleted(String[] time_distance); }
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);
} }
private class ParserTask extends AsyncTask<String, Integer,
List<HashMap<String, String>>> {
// Parsing the data in non-ui thread
@Override
protected List<HashMap<String, String>> doInBackground(String... jsonData) {
JSONObject jObject;
List<HashMap<String, String>> routes = null;
try {
jObject = new JSONObject(jsonData[0]);
DistanceTimeParser parser = new DistanceTimeParser();
// 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<HashMap<String, String>> result) {
String duration_distance = "";
if (result.size() < 1) {
Log.e("Error : ", "No Points found");
return;
}
String[] date_dist = new String[2];
// Traversing through all the routes
for (int i = 0; i < result.size(); i++) {
// Fetching i-th route
HashMap<String, String> tmpData = result.get(i);
Set<String> key = tmpData.keySet();
Iterator it = key.iterator();
while (it.hasNext()) {
String hmKey = (String) it.next();
duration_distance = tmpData.get(hmKey);
System.out.println("Key: " + hmKey + " & Data: " + duration_distance);
it.remove(); // avoids a ConcurrentModificationException
}
date_dist[i] = duration_distance;
}
mTaskListener.taskCompleted(date_dist);
} } }
DistanceTimeParser.java（添加了新类）
public class DistanceTimeParser {
public List<HashMap<String, String>> parse(JSONObject jObject) {
List<HashMap<String, String>> routes = new ArrayList<HashMap<String, String>>();
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONObject jDistance = null;
JSONObject jDuration = null;
try {
jRoutes = jObject.getJSONArray("routes");
jLegs = ((JSONObject) jRoutes.get(0)).getJSONArray("legs");
List<HashMap<String, String>> path = new ArrayList<HashMap<String, String>>();
/** Getting distance from the json data */
jDistance = ((JSONObject) jLegs.get(0)).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(0)).getJSONObject("duration");
HashMap<String, String> hmDuration = new HashMap<String, String>();
hmDuration.put("duration", jDuration.getString("text"));
routes.add(hmDistance);
routes.add(hmDuration);
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
}
return routes;
} }
DirectionsJSONParser.java（添加了新类）
public class DirectionsJSONParser {
List<List<HashMap<String,String>>> parse(JSONObject jObject){
List<List<HashMap<String, String>>> routes = new ArrayList<>() ;
JSONArray jRoutes ;
JSONArray jLegs ;
JSONArray jSteps ;
try {
jRoutes = jObject.getJSONArray("routes");
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<>();
for(int j=0;j<jLegs.length();j++){
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
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<>();
hm.put("lat", Double.toString((list.get(l)).latitude) );
hm.put("lng", Double.toString((list.get(l)).longitude) );
path.add(hm);
}
}
routes.add(path);
}
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception ignored){
}
return routes;
}
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<>();
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;
} }
在mapsActivity.java中添加了这4个方法
private String getDirectionsUrl(LatLng origin, LatLng dest) {
String str_origin = "origin=" + origin.latitude + "," + origin.longitude;
String str_dest = "destination=" + dest.latitude + "," + dest.longitude;
String sensor = "sensor=false";
String parameters = str_origin + "&" + str_dest + "&" + sensor;
String output = "json";
return "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;
}
@SuppressLint("NewApi")
public static String downloadUrl(String strUrl) throws IOException {
String data = "";
HttpURLConnection urlConnection;
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
try (InputStream 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) {
Log.d("Exception while down", e.toString());
} finally {
urlConnection.disconnect();
}
return data;
}
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);
}
}
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]);
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 = new ArrayList<>();
PolylineOptions lineOptions = new PolylineOptions();
for (int i = 0; i < result.size(); i++) {
List<HashMap<String, String>> path = result.get(i);
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);
}
lineOptions.addAll(points);
lineOptions.width(10);
lineOptions.color(Color.WHITE);
mMap.addPolyline(lineOptions);
}
}
}
mapsActivity.java（我在地图中的当前位置）
@Override
public void onLocationChanged(Location location) {
Log.d("onLocationChanged", "entered");
mLastLocation = location;
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = new Date();
mLastUpdateTime = ((dateFormat.format(date).toString()));
saveToFirebase();
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
latitude = location.getLatitude();
longitude = location.getLongitude();
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.draggable(false);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mMap.addMarker(markerOptions);
//move map camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mMap.animateCamera(CameraUpdateFactory.zoomTo(11));
Toast.makeText(MapsActivity.this, "Your Current Location", Toast.LENGTH_LONG).show();
//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient,
this);
Log.d("onLocationChanged", "Removing Location Updates");
}
}
Fire Base 方法中保存的数据
public void saveToFirebase() {
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Email").push();
String email = FirebaseAuth.getInstance().getCurrentUser().getEmail();
UserInformation userInformation = new UserInformation(email, mLastLocation.getLatitude(), mLastLocation.getLongitude());
ref.setValue(userInformation);
}
