在地图上的某个地方获取高度

Question

我使用以下代码获取坐标和高度，只需单击地图上的某个位置...例如，如果我单击纽约街道，应用程序会返回给我纽约坐标

public void onLocationChanged(Location location) {
    double lat = (double) (location.getLatitude());
    double lng = (double) (location.getLongitude());
    double alt = (double) (location.getAltitude());
}

我使用这个方法来检索一个地方的触摸位置数据

@Override
public boolean onTap(GeoPoint p, MapView map) {     

    List<Overlay> overlays = map.getOverlays();

    Message message = new Message();

    Bundle data = new Bundle();

    data.putInt("latitude", p.getLatitudeE6());

    data.putInt("longitude", p.getLongitudeE6());

    message.setData(data);

    handler.sendMessage(message);       

    return super.onTap(p, map);
}   

不幸的是，GeoPoint 对象似乎没有像 p.getAltitudeE6() 这样的方法来模拟经度和纬度。

因此，点击地图获取纬度和经度可以正常工作，但高度在每个点击的地方都会返回 0。

有没有办法解决这个问题？

Answer 1

地图数据不包括海拔信息。您可以使用Google Elevation API 获取您拥有的纬度和经度并获得海拔高度。这是一个在线查找，因此不一定非常敏感。

添加代码示例。

public double getAltitudeFromNet(double def, Location loc) {
Log.v(TAG, "Looking up net altitude");
double result = -100000.0;
HttpParams httpParameters = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParameters, 5000);
HttpConnectionParams.setSoTimeout(httpParameters, 5000);

HttpClient httpClient = new DefaultHttpClient(httpParameters);
HttpContext localContext = new BasicHttpContext();
String url = "http://maps.googleapis.com/maps/api/elevation/" + "xml?locations="
    + String.valueOf(loc.getLatitude()) + "," + String.valueOf(loc.getLongitude()) + "&sensor=true";
HttpGet httpGet = new HttpGet(url);
try {
  HttpResponse response = httpClient.execute(httpGet, localContext);
  HttpEntity entity = response.getEntity();
  if (entity != null) {
    InputStream instream = entity.getContent();
    int r = -1;
    StringBuffer respStr = new StringBuffer();
    while ((r = instream.read()) != -1)
      respStr.append((char) r);
    String tagOpen = "<elevation>";
    String tagClose = "</elevation>";
    if (respStr.indexOf(tagOpen) != -1) {
      int start = respStr.indexOf(tagOpen) + tagOpen.length();
      int end = respStr.indexOf(tagClose);
      String value = respStr.substring(start, end);
      result = (double) (Double.parseDouble(value));

    }
    instream.close();
  }
} catch (ClientProtocolException e) {
  Log.w(TAG, "Looking up net altitude ClientProtocolException", e);
} catch (IOException e) {
  Log.w(TAG, "Looking up net altitude IOException", e);
}

Log.i(TAG, "got net altitude " + (int) result);
if (result > -1000) {
  return result;
} else {
  return def;
}
}