如何在 Google 地图中全天跟踪用户的位置？

Question

您将如何跟踪用户一整天的位置，例如 Google 地图中的时间轴？

我有两个想法

1. 例如，如果我每天有 200 个 LatLng 值，我如何将所有这些 LatLng 值作为点传递到 Google 地图？我有一个 google doc reference，因为我最多只能跟踪 10 个位置点。

2. 有没有GoogleAPI可以全天跟踪用户并做一个时间线的？

Answer 1

如果你有 200 个 LatLng 点，你总是可以将它们绘制为 polyline:

...
final List<LatLng> polylinePoints = new ArrayList<>();
polylinePoints.add(new LatLng(<Point1_Lat>, <Point1_Lng>));
polylinePoints.add(new LatLng(<Point2_Lat>, <Point2_Lng>));
...

final Polyline polyline = mGoogleMap.addPolyline(new PolylineOptions()
        .addAll(polylinePoints)
        .color(Color.BLUE)
        .width(20));

并且，如果需要，使用 Snap to Road part of Google Maps Roads API:

将它们贴到道路上

...
List<LatLng> snappedPoints = new ArrayList<>();
new GetSnappedPointsAsyncTask().execute(polylinePoints, null, snappedPoints);
...

private class GetSnappedPointsAsyncTask extends AsyncTask<List<LatLng>, Void, List<LatLng>> {

    protected void onPreExecute() {
        super.onPreExecute();
    }

    protected List<LatLng> doInBackground(List<LatLng>... params) {

        List<LatLng> snappedPoints = new ArrayList<>();

        HttpURLConnection connection = null;
        BufferedReader reader = null;

        try {
            URL url = new URL(buildRequestUrl(params[0]));
            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();

            InputStream stream = connection.getInputStream();

            reader = new BufferedReader(new InputStreamReader(stream));
            StringBuilder jsonStringBuilder = new StringBuilder();

            StringBuffer buffer = new StringBuffer();
            String line = "";

            while ((line = reader.readLine()) != null) {
                buffer.append(line+"\n");
                jsonStringBuilder.append(line);
                jsonStringBuilder.append("\n");
            }

            JSONObject jsonObject = new JSONObject(jsonStringBuilder.toString());
            JSONArray snappedPointsArr = jsonObject.getJSONArray("snappedPoints");

            for (int i = 0; i < snappedPointsArr.length(); i++) {
                JSONObject snappedPointLocation = ((JSONObject) (snappedPointsArr.get(i))).getJSONObject("location");
                double lattitude = snappedPointLocation.getDouble("latitude");
                double longitude = snappedPointLocation.getDouble("longitude");
                snappedPoints.add(new LatLng(lattitude, longitude));
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.disconnect();
            }
            try {
                if (reader != null) {
                    reader.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return snappedPoints;
    }

    @Override
    protected void onPostExecute(List<LatLng> result) {
        super.onPostExecute(result);

        PolylineOptions polyLineOptions = new PolylineOptions();
        polyLineOptions.addAll(result);
        polyLineOptions.width(5);
        polyLineOptions.color(Color.RED);
        mGoogleMap.addPolyline(polyLineOptions);

        LatLngBounds.Builder builder = new LatLngBounds.Builder();
        builder.include(result.get(0));
        builder.include(result.get(result.size()-1));
        LatLngBounds bounds = builder.build();
        mGoogleMap.animateCamera(CameraUpdateFactory.newLatLngBounds(bounds, 10));

    }
}


private String buildRequestUrl(List<LatLng> trackPoints) {
    StringBuilder url = new StringBuilder();
    url.append("https://roads.googleapis.com/v1/snapToRoads?path=");

    for (LatLng trackPoint : trackPoints) {
        url.append(String.format("%8.5f", trackPoint.latitude));
        url.append(",");
        url.append(String.format("%8.5f", trackPoint.longitude));
        url.append("|");
    }
    url.delete(url.length() - 1, url.length());
    url.append("&interpolate=true");
    url.append(String.format("&key=%s", <your_Google_Maps_API_key>);

    return url.toString();
}

如果相邻点之间的距离太大，您可以使用 Waypoints part of Directions API 获取这些点之间的方向，并根据 waypoints 请求的结果绘制折线。

Answer 2

我终于找到了解决方案，您可以每 15 分钟获取一次 latlng，随心所欲。

我从 google 示例 github 中获得参考，我们可以 运行 使用 PendingIntent 的后台服务，或者我们可以使用广播接收器。

  public class LocationUpdatesIntentService extends IntentService {

    private static final String ACTION_PROCESS_UPDATES =
            "com.google.android.gms.location.sample.locationupdatespendingintent.action" +
                    ".PROCESS_UPDATES";
    private static final String TAG = LocationUpdatesIntentService.class.getSimpleName();


    public LocationUpdatesIntentService() {
        // Name the worker thread.
        super(TAG);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        if (intent != null) {
            final String action = intent.getAction();
            if (ACTION_PROCESS_UPDATES.equals(action)) {
                LocationResult result = LocationResult.extractResult(intent);
                if (result != null) {
                    List<Location> locations = result.getLocations();
                    Utils.setLocationUpdatesResult(this, locations);
                    Utils.sendNotification(this, Utils.getLocationResultTitle(this, locations));
                    Log.i(TAG, Utils.getLocationUpdatesResult(this));
                }
            }
        }
    }
}

这里完整参考： https://github.com/googlesamples/android-play-location

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