我目前正在尝试利用Google的Directions API中请求的JSON数据在两个目的地之间绘制路线 . 我目前的版本适用于150英里范围内的目的地 . 然而，当我尝试在状态中绘制多边形线时，应用程序崩溃了 . 下面是我的Async任务的片段 .
public class FetchRouteStepsFromService extends AsyncTask<Void,Void,StringBuilder> {
private LocalBroadcastManager manager;
private String currentAddress;
private String destinationAddress;
public FetchRouteStepsFromService(String currentAddress, String destinationAddress, Context context){
this.currentAddress = currentAddress;
this.destinationAddress = destinationAddress;
manager = LocalBroadcastManager.getInstance(context);
}
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;
}
@Override
protected void onPostExecute(StringBuilder result) {
super.onPostExecute(result);
try{
JSONObject jsonObj = new JSONObject(result.toString());
JSONArray routesJSONArray = jsonObj.getJSONArray("routes");
JSONObject beforeLegsJSONObject = routesJSONArray.getJSONObject(0);
JSONArray legsJSONArray = beforeLegsJSONObject.getJSONArray("legs");
JSONObject beforeStepsJSONObject = legsJSONArray.getJSONObject(0);
JSONArray stepsJSONArray = beforeStepsJSONObject.getJSONArray("steps");
List<LatLng> test = new ArrayList<>();
ArrayList<PolylineOptions> options = new ArrayList<>();
map.clear();
for(int i = 0; i < stepsJSONArray.length(); i++){
JSONObject object = stepsJSONArray.getJSONObject(i);
JSONObject polyLineObject = object.getJSONObject("polyline");
String encodedPoly = polyLineObject.getString("points");//Holds the code for the polyline (String)
test = decodePoly(encodedPoly);
//Todo: Maybe create a separate asynctask to add latlngs on separate thread?
for(int j = 0; j < test.size();j++){
PolylineOptions options1;
if(j != test.size() -1) {
LatLng startLocation = test.get(j);
LatLng nextLocation = test.get(j + 1);
options1 = new PolylineOptions().add(startLocation, nextLocation).width(5).color(Color.GREEN).geodesic(true);
map.addPolyline(options1);
}else{
LatLng startLocation = test.get(j);
LatLng nextLocation = test.get(j);
options1 = new PolylineOptions().add(startLocation, nextLocation).width(5).color(Color.GREEN).geodesic(true);
map.addPolyline(options1);
}
}
}
dialog.dismiss();
updateUI();
}catch (Exception e){
e.printStackTrace();
}
}
@Override
protected StringBuilder doInBackground(Void... params) {
try{
StringBuilder jsonResults = new StringBuilder();
String googleMapUrl = "https://maps.googleapis.com/maps/api/directions/json?" +
"origin="+currentAddress+"&" +
"destination="+destinationAddress+"&key=MY_KEY";
URL url = new URL(googleMapUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStreamReader in = new InputStreamReader(conn.getInputStream());
int read;
char[] buff = new char[3000];
while((read = in.read(buff,0,3000)) != -1 ){
jsonResults.append(buff,0,read);
}
return jsonResults;
}catch (Exception e){
Log.d("PlanTrip","doInBackgroud exception");
e.printStackTrace();
}
return null;
}
}
这是我的Fragment中的本地类，它包含Google Map . 我以前曾试图让这个AsyncTask成为自己的类 . 该类将广播由PolyLineOptions组成的意图，该意图将由片段的BroadcastReceiver接收 . 虽然这也不起作用 . 任何资源，建议或反馈将不胜感激 .
编辑1：大型请求期间的Logcat
