我在添加折线时遇到了性能问题，并认为可能会将它们添加到扩展AsyncTask的单独类中。但是，当我了解到UI元素无法以这种方式添加（并且折线是UI元素）。
为什么我在绘制折线时遇到性能问题？好吧，我的折线不是从pos A到pos B，而是从我当前的位置到目的地（为了应用atm而硬编码）。因此，当执行onLocationChange侦听器时会绘制折线，因此我的应用程序需要大量的处理能力。
在这种情况下如何使用AsyncTask的任何想法？
这是主要课程：
mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {
@Override
public void onMyLocationChange(Location arg0) {
// Get positions!
currentPOS = new LatLng(arg0.getLatitude(), arg0.getLongitude());
LatLng dst = new LatLng(58.378249, 26.714673);
CameraUpdate yourLocation = CameraUpdateFactory.newLatLngZoom(currentPOS, 13);
mMap.animateCamera(yourLocation);
mMap.addMarker(new MarkerOptions().position(dst).title("SCHOOL!"));
/*
// Remove comments to add marker to Liivi 2!
mMap.addMaker(new MarkerOptions().position(currentPOS).title("My POS"));
*/
if (currentPOS != null) {
//This is supposed to show directions
DirectionAPI directionAPI = new DirectionAPI(currentPOS, dst);
GoogleResponse googleResponse = null;
try {
googleResponse = (GoogleResponse) directionAPI.execute().get();
} catch (InterruptedException e) {
Log.e("CATCH","INTERRUPDED");
e.printStackTrace();
} catch (ExecutionException e) {
Log.e("CATCH","EXECUTIONEXCEPTION");
e.printStackTrace();
}
if (googleResponse.isOk()){
DrivingDirection drivingDirection = new DrivingDirection(googleResponse.getJsonObject());
polyline = drivingDirection.getTotalPolyline();
new drawPath(mMap,polyline).execute();
}
}
}
});
这是路径绘图的异步（由于UI冲突会导致错误）：
import android.graphics.Color;
import android.os.AsyncTask;
import com.google.android.gms.maps.GoogleMap;
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 java.util.ArrayList;
/**
* Created by Kevin on 7.10.2015.
*/
public class drawPath extends AsyncTask{
private static ArrayList<LatLng> polyline;
private static GoogleMap mMap;
public drawPath(GoogleMap map, ArrayList<LatLng> polyline){
this.mMap = map;
this.polyline = polyline;
}
@Override
protected Object doInBackground(Object[] params) {
for (int i = 0; i < polyline.size() - 1; i++) {
LatLng src = polyline.get(i);
LatLng dest = polyline.get(i + 1);
// mMap is the Map Object
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)
);
}
return null;
}
}
答案 0 :(得分：1)
我解决了这个问题，我没有单独添加每个折线图，而是整个折线。例如，在我离目的地大约4公里的位置之前，它之间有280条折线。在每个onLocationChange上，这些折线一个接一个地绘制成地图。现在他们一次全部添加 - AsyncTask将在后台创建折线，在后执行中他们将被添加。
@Override
protected Object doInBackground(Object[] params) {
PolylineOptions options = new PolylineOptions().width(5).color(Color.BLUE).geodesic(true);
for (int z = 0; z < polyline.size(); z++) {
LatLng point = polyline.get(z);
options.add(point);
}
return options;
}
protected void onPostExecute(Object result) {
Polyline line = mMap.addPolyline((PolylineOptions) result);
}
答案 1 :(得分：0)
您可以使用此代码
ublic class DrawrootTask extends AsyncTask<String, String, String> {
private Context context;
public static boolean flagCompleted = false;
private GoogleMap googleMap;
private double source_lat = 0.0;
private double source_long = 0.0;
private double dest_lat = 0.0;
private double dest_long = 0.0;
Userdata userdata;
String tag = "DrawRootTask";
private ProgressDialog progressDialog;
public static double dist, time;
private Polyline line;
String distanceText = "";
String durationText = "";
public DrawrootTask(Context context, LatLng source, LatLng destination,
GoogleMap googleMap) {
source_lat = source.latitude;
source_long = source.longitude;
dest_lat = destination.latitude;
dest_long = destination.longitude;
this.googleMap = googleMap;
this.context = context;
userdata = Userdata.getinstance(context);
}
protected void onPreExecute() {
// // TODO Auto-generated method stub
super.onPreExecute();
progressDialog = new ProgressDialog(context);
progressDialog.setMessage(context.getResources().getString(
R.string.please_wait));
progressDialog.setIndeterminate(true);
progressDialog.show();
}
@Override
protected String doInBackground(String... params) {
String json = "";
// constructor
StringBuilder urlString = new StringBuilder();
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
HashMap<String, String> keyValue = new HashMap<String, String>();
urlString.append("?origin=");// from
urlString.append(Double.toString(source_lat));
urlString.append(",");
urlString.append(Double.toString(source_long));
urlString.append("&destination=");// to
urlString.append(Double.toString(dest_lat));
urlString.append(",");
urlString.append(Double.toString(dest_long));
urlString.append("&sensor=false&mode=driving&alternatives=true");
// defaultHttpClient
String url = urlString.toString();
FetchUrl fetchurl = new FetchUrl();
json = fetchurl.fetchUrl(url, keyValue);
Log.e("Buffer Error", json);
return json;
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
try {
progressDialog.dismiss();
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);
line = googleMap.addPolyline(new PolylineOptions()
.add(new LatLng(src.latitude, src.longitude),
new LatLng(dest.latitude, dest.longitude))
// .width(8).color(Color.BLUE).geodesic(true));
.width(8)
.color(context.getResources().getColor(
R.color.actionbar_color)).geodesic(true));
Log.i("draw root", "" + "" + line.toString());
}
JSONArray legs = routes.getJSONArray("legs");
JSONObject steps = legs.getJSONObject(0);
JSONObject duration = steps.getJSONObject("duration");
JSONObject distance = steps.getJSONObject("distance");
distanceText = distance.getString("text");
durationText = duration.getString("text");
Log.i("draw root", "" + distance.toString());
dist = Double.parseDouble(distance.getString("text").replaceAll(
"[^\\.0123456789]", ""));
time = Double.parseDouble(duration.getString("text").replaceAll(
"[^\\.0123456789]", ""));
userdata.setDistance(distanceText);
userdata.setTime(durationText);
Log.d(tag, "distace is " + dist + " time is " + time);
flagCompleted = true;
} catch (JSONException e) {
Log.d("draw root", "" + e);
}
}
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;
}
}