这是在源和目的地之间绘制路线的源代码：
public class MapActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private SupportMapFragment mapFragment;
private GoogleMap map;
private GoogleApiClient mGoogleApiClient;
ArrayList markerPoints;
private LocationRequest mLocationRequest;
private long UPDATE_INTERVAL = 15000; /* 15 secs */
private long FASTEST_INTERVAL = 5000; /* 5 secs */
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
// Marker marker;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (!isGooglePlayServicesAvailable()) {
finish();
}
setContentView(R.layout.activity_map);
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setDisplayShowCustomEnabled(true);
getSupportActionBar().setCustomView(R.layout.custom_actionbar_maps);
markerPoints = new ArrayList();
mapFragment = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map));
if (mapFragment != null) {
mapFragment.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap map) {
loadMap(map);
}
});
} else {
Toast.makeText(this, "Error - Map Fragment was null!!", Toast.LENGTH_SHORT).show();
}
}
protected void loadMap(GoogleMap googleMap) {
map = googleMap;
if (map != null) {
// Map is ready
Toast.makeText(this, "Map Fragment was loaded properly!", Toast.LENGTH_SHORT).show();
map.setMyLocationEnabled(true);
map.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
@Override
public void onMapClick(LatLng point) {
// Already two locations
if(markerPoints.size()>1){
markerPoints.clear();
map.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 Android API V2
map.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 = getDirectionsUrl(origin, dest);
DownloadTask downloadTask = new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
}
}
});
// Now that map has loaded, let's get our location!
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(LocationServices.API)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this).build();
connectClient();
} else {
Toast.makeText(this, "Error - Map was null!!", Toast.LENGTH_SHORT).show();
}
}
protected void connectClient() {
// Connect the client.
if (isGooglePlayServicesAvailable() && mGoogleApiClient != null) {
mGoogleApiClient.connect();
}
}
/*
* Called when the Activity becomes visible.
*/
@Override
protected void onStart() {
super.onStart();
connectClient();
}
/*
* Called when the Activity is no longer visible.
*/
@Override
protected void onStop() {
// Disconnecting the client invalidates it.
if (mGoogleApiClient != null) {
mGoogleApiClient.disconnect();
}
super.onStop();
}
/*
* Handle results returned to the FragmentActivity by Google Play services
*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// Decide what to do based on the original request code
switch (requestCode) {
case CONNECTION_FAILURE_RESOLUTION_REQUEST:
/*
* If the result code is Activity.RESULT_OK, try to connect again
*/
switch (resultCode) {
case Activity.RESULT_OK:
mGoogleApiClient.connect();
break;
}
}
}
// Fetches data from url passed
private boolean isGooglePlayServicesAvailable() {
// Check that Google Play services is available
int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
// If Google Play services is available
if (ConnectionResult.SUCCESS == resultCode) {
// In debug mode, log the status
Log.d("Location Updates", "Google Play services is available.");
return true;
} else {
// Get the error dialog from Google Play services
Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(resultCode, this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
// If Google Play services can provide an error dialog
if (errorDialog != null) {
// Create a new DialogFragment for the error dialog
ErrorDialogFragment errorFragment = new ErrorDialogFragment();
errorFragment.setDialog(errorDialog);
errorFragment.show(getSupportFragmentManager(), "Location Updates");
}
return false;
}
}
/*
* Called by Location Services when the request to connect the client
* finishes successfully. At this point, you can request the current
* location or start periodic updates
*/
@Override
public void onConnected(Bundle dataBundle) {
// Display the connection status
Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (location != null) {
Toast.makeText(this, "GPS location was found!", Toast.LENGTH_SHORT).show();
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 16);
map.animateCamera(cameraUpdate);
//marker = map.addMarker(new MarkerOptions().position(latLng).icon(BitmapDescriptorFactory.fromResource(R.drawable.vehicle_marker)).flat(true).anchor(0.5f,0.5f));
startLocationUpdates();
} else {
Toast.makeText(this, "Current location was null, enable GPS on emulator!", Toast.LENGTH_SHORT).show();
}
}
protected void startLocationUpdates() {
mLocationRequest = new LocationRequest();
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
mLocationRequest.setInterval(UPDATE_INTERVAL);
mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
mLocationRequest, this);
}
public void onLocationChanged(Location location) {
// Report to the UI that the location was updated
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
/* if(marker == null){
*//* marker.remove();*//*
marker = map.addMarker(new MarkerOptions().position(latLng).icon(BitmapDescriptorFactory.fromResource(R.drawable.vehicle_marker)));
}
marker.setPosition(latLng);
*/
CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 16);
map.animateCamera(cameraUpdate);
String msg = "Updated Location: " +
Double.toString(location.getLatitude()) + "," +
Double.toString(location.getLongitude());
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
}
/*
* Called by Location Services if the connection to the location client
* drops because of an error.
*/
@Override
public void onConnectionSuspended(int i) {
if (i == CAUSE_SERVICE_DISCONNECTED) {
Toast.makeText(this, "Disconnected. Please re-connect.", Toast.LENGTH_SHORT).show();
} else if (i == CAUSE_NETWORK_LOST) {
Toast.makeText(this, "Network lost. Please re-connect.", Toast.LENGTH_SHORT).show();
}
}
/*
* Called by Location Services if the attempt to Location Services fails.
*/
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
/*
* Google Play services can resolve some errors it detects. If the error
* has a resolution, try sending an Intent to start a Google Play
* services activity that can resolve error.
*/
if (connectionResult.hasResolution()) {
try {
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
/*
* Thrown if Google Play services canceled the original
* PendingIntent
*/
} catch (IntentSender.SendIntentException e) {
// Log the error
e.printStackTrace();
}
} else {
Toast.makeText(getApplicationContext(),
"Sorry. Location services not available to you", Toast.LENGTH_LONG).show();
}
}
// Define a DialogFragment that displays the error dialog
public static class ErrorDialogFragment extends DialogFragment {
// Global field to contain the error dialog
private Dialog mDialog;
// Default constructor. Sets the dialog field to null
public ErrorDialogFragment() {
super();
mDialog = null;
}
// Set the dialog to display
public void setDialog(Dialog dialog) {
mDialog = dialog;
}
// Return a Dialog to the DialogFragment.
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return mDialog;
}
}
// 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 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();
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(12);
lineOptions.color(Color.RED);
lineOptions.geodesic(true);
}
// Drawing polyline in the Google Map for the i-th route
map.addPolyline(lineOptions);
}
}
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){
Log.d("Exception while downloading url", e.toString());
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
}
DirectionsJSONParser.java 如下：
import com.google.android.gms.maps.model.LatLng;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class DirectionsJSONParser {
/** Receives a JSONObject and returns a list of lists containing latitude and longitude */
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;
try {
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<HashMap<String, String>>();
/** Traversing all legs */
for(int j=0;j<jLegs.length();j++){
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for(int k=0;k<jSteps.length();k++){
String polyline = "";
polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points");
List list = decodePoly(polyline);
/** Traversing all points */
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);
}
}
routes.add(path);
}
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception e){
}
return routes;
}
/**
* Method to decode polyline points
* Courtesy : http://jeffreysambells.com/2010/05/27/decoding-polylines-from-google-maps-direction-api-with-java
* */
private List decodePoly(String encoded) {
List 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;
}
}