我是android的新手，这是我的代码，问题是这段代码无法在地图上绘制路径。
这是我的主要活动
import android.graphics.Color;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;
import org.w3c.dom.Document;
import java.util.ArrayList;
public class servicing extends AppCompatActivity implements OnMapReadyCallback, LocationListener {
protected GoogleMap mMap;
String lang = "english";
String test = "test";
protected LocationManager locationManager;
Route route = new Route();
LatLng latLng1 = new LatLng(26.903291,75.792482);
LatLng latLng2 = new LatLng(26.907708,75.806044);
ArrayList<LatLng> points = new ArrayList<>(2);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_servicing);
//GMapV2Direction md = new GMapV2Direction();
MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
/*Document doc = md.getDocument(latLng1, latLng2,
GMapV2Direction.MODE_DRIVING);
ArrayList<LatLng> directionPoint = md.getDirection(doc);
PolylineOptions rectLine = new PolylineOptions().width(3).color(
Color.RED);
for (int i = 0; i < directionPoint.size(); i++) {
rectLine.add(directionPoint.get(i));
}
Polyline polylin = mMap.addPolyline(rectLine);*/
points.add(latLng1);
points.add(latLng2);
route.drawRoute(mMap, this, points, true, lang, false);
Toast.makeText(getApplicationContext(),driverdata.extrastmt,Toast.LENGTH_LONG).show();
//route.drawRoute(mMap,this,latLng1,latLng2,lang);
}
@Override
public void onMapReady(GoogleMap googleMap){
mMap = googleMap;
mMap.setMyLocationEnabled(true);
mMap.animateCamera(CameraUpdateFactory.zoomTo(15), 2000, null);
CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom((latLng1),15);
mMap.animateCamera(cameraUpdate);
//route.drawRoute(mMap, this, points, true, lang, false);
}
@Override
public void onProviderEnabled(String provider) {
(Toast.makeText(getApplication(), "Reconnecting", Toast.LENGTH_LONG)).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(getApplication(),"Connection Failed! Check Network!",Toast.LENGTH_LONG).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
Log.d("Latitude", "status");
}
@Override
public void onLocationChanged(Location location) {
Log.d("Latitude", "status");
}
}
这是我的路线类
public class Route {
GoogleMap mMap;
Context context;
String lang;
static String LANGUAGE_SPANISH = "es";
static String LANGUAGE_ENGLISH = "en";
static String LANGUAGE_FRENCH = "fr";
static String LANGUAGE_GERMAN = "de";
static String LANGUAGE_CHINESE_SIMPLIFIED = "zh-CN";
static String LANGUAGE_CHINESE_TRADITIONAL = "zh-TW";
static String TRANSPORT_DRIVING = "driving";
static String TRANSPORT_WALKING = "walking";
static String TRANSPORT_BIKE = "bicycling";
static String TRANSPORT_TRANSIT = "transit";
public boolean drawRoute(GoogleMap map, Context c, ArrayList<LatLng> points, boolean withIndications, String language, boolean optimize)
{
mMap = map;
context = c;
lang = language;
if(points.size() == 2)
{
String url = makeURL(points.get(0).latitude,points.get(0).longitude,points.get(1).latitude,points.get(1).longitude,"driving");
new connectAsyncTask(url,withIndications).execute();
return true;
}
else if(points.size() > 2)
{
String url = makeURL(points,"driving",optimize);
new connectAsyncTask(url,withIndications).execute();
return true;
}
return false;
}
private String makeURL (ArrayList<LatLng> points, String mode, boolean optimize){
StringBuilder urlString = new StringBuilder();
if(mode == null)
mode = "driving";
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append( points.get(0).latitude);
urlString.append(',');
urlString.append(points.get(0).longitude);
urlString.append("&destination=");
urlString.append(points.get(points.size()-1).latitude);
urlString.append(',');
urlString.append(points.get(points.size()-1).longitude);
urlString.append("&waypoints=");
if(optimize)
urlString.append("optimize:true|");
urlString.append( points.get(1).latitude);
urlString.append(',');
urlString.append(points.get(1).longitude);
for(int i=2;i<points.size()-1;i++)
{
urlString.append('|');
urlString.append( points.get(i).latitude);
urlString.append(',');
urlString.append(points.get(i).longitude);
}
urlString.append("&sensor=true&mode="+mode);
return urlString.toString();
}
private String makeURL (double sourcelat, double sourcelog, double destlat, double destlog,String mode){
StringBuilder urlString = new StringBuilder();
if(mode == null)
mode = "driving";
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append(Double.toString(sourcelat));
urlString.append(",");
urlString
.append(Double.toString( sourcelog));
urlString.append("&destination=");// to
urlString
.append(Double.toString( destlat));
urlString.append(",");
urlString.append(Double.toString( destlog));
urlString.append("&sensor=false&mode="+mode+"&alternatives=true&language="+lang);
return urlString.toString();
}
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;
boolean steps;
connectAsyncTask(String urlPass, boolean withSteps){
url = urlPass;
steps = withSteps;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
progressDialog = new ProgressDialog(context);
progressDialog.setMessage("Fetching route, Please wait...");
progressDialog.setIndeterminate(true);
progressDialog.show();
}
@Override
protected String doInBackground(Void... params) {
JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);
return json;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
progressDialog.hide();
if(result!=null){
driverdata.extrastmt = result;
drawPath(result, steps);
//makeT(result);
}else{
driverdata.extrastmt="null";
}
}
}
private void drawPath(String result, boolean withSteps) {
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(encodedString);
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(4)
.color(Color.BLUE).geodesic(true));
}
if(withSteps)
{
JSONArray arrayLegs = routes.getJSONArray("legs");
JSONObject legs = arrayLegs.getJSONObject(0);
JSONArray stepsArray = legs.getJSONArray("steps");
//put initial point
for(int i=0;i<stepsArray.length();i++)
{
Step step = new Step(stepsArray.getJSONObject(i));
mMap.addMarker(new MarkerOptions()
.position(step.location)
.title(step.distance)
.snippet(step.instructions)
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
}
}
}
catch (JSONException e) {
}
}
/**
* Class that represent every step of the directions. It store distance, location and instructions
*/
private class Step
{
public String distance;
public LatLng location;
public String instructions;
Step(JSONObject stepJSON)
{
JSONObject startLocation;
try {
distance = stepJSON.getJSONObject("distance").getString("text");
startLocation = stepJSON.getJSONObject("start_location");
location = new LatLng(startLocation.getDouble("lat"),startLocation.getDouble("lng"));
try {
instructions = URLDecoder.decode(Html.fromHtml(stepJSON.getString("html_instructions")).toString(), "UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
};
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
最后是JSONParser类
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public String getJSONFromUrl(String url) {
// Making HTTP request
try {
URL urlnew = new URL(url);
HttpURLConnection urlConnection = (HttpURLConnection) urlnew.openConnection();
is = new BufferedInputStream(urlConnection.getInputStream());
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
json = sb.toString();
is.close();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
Log.d("JSON_RUTA", json);
return json;
}
}
请我需要帮助，而且它取得数据但是在地图活动上，即服务活动，吐司什么都没有，一旦你按下然后再按下按钮开始服务活动，吐司会提供以前的结果，但是没有路线可以在地图上看到。
答案 0 :(得分：0)
我找到了解决方案，基本上，我在将点添加到列表之前调用route.drawroute（），因此它返回null。