问题描述

我对 Android 中的 onLocationChanged 事件有疑问.这是触发:

I have a problem with onLocationChanged event in Android. Here's the triggering:

case R.id.start: {
    Points.add(overlay.getMyLocation()); // Points' type is ArrayList<GeoPoint>
    mgr.requestLocationUpdates(best, 0, 3, locationListener);
    }
    break;

这是 onLocationChanged 方法:

And here's the onLocationChanged method:

public void onLocationChanged(Location location) {
    i++;
    Points.add(overlay.getMyLocation());
    MapOverlay mapOverlay = new MapOverlay(Points.get(i-1), Points.get(i));
    map.getOverlays().add(mapOverlay); //does the drawing
    mMapController.animateTo(Points.get(i));
}

因此，onLocationChanged 仅在我按下开始"后才被调用一次.它应该在每次位置更改时自动调用，对吗?在我的情况下，它不是.
请帮帮我.

So, onLocationChanged is called only once and only after I press "start". It's supposed to be called automatically every time the location has changed, right? In my case, it's not.
Please help me.

推荐答案

问题似乎解决了.在 onCreate 中，我添加了:

Problem seems to be solved. In onCreate, I added:

Criteria crit = new Criteria();
crit.setAccuracy(Criteria.ACCURACY_FINE);
best = mgr.getBestProvider(crit, false);
mgr.requestLocationUpdates(best, 0, 1, locationListener);

onLocationChanged 现在看起来像这样:

onLocationChanged now looks like that:

@Override
public void onLocationChanged(Location location) {
    i++;
    nextPoint = overlay.getMyLocation();
    latitude = nextPoint.getLatitudeE6();
    longtitude = nextPoint.getLongitudeE6();
    lastPoint = new GeoPoint((int) latitude, (int) longtitude);
    Points.add(lastPoint);
    MapOverlay mapOverlay = new MapOverlay(Points.get(i - 1), Points.get(i));
    map.getOverlays().add(mapOverlay);
    mMapController.animateTo(Points.get(i));
    nextPoint = null;
    lastPoint = null;
}

另外，非常重要的方法:

Also, very important methods:

@Override
protected void onResume() {
    super.onResume();
    mgr.requestLocationUpdates(best, 10000, 1, locationListener);
}

@Override
protected void onPause() {
    super.onPause();
    mgr.removeUpdates(locationListener);
}

还有一些新的权限:

<uses-permission android:name="android.permission.ACCESS_GPS" />
        <uses-permission android:name="android.permission.ACCESS_LOCATION" />
        <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
        <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
        <uses-permission android:name="android.permission.INTERNET" />

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