如何（何时？）如果可能的话，取消LocationManager.RequestSingleUpdate？

Question

public void getGPS(View view) {
    // load all available Location providers
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    List<String> providers = locationManager.getProviders(false);
    // determine the last known location within 2 hours available from cache
    Location myLocation = null;
    Date now = new Date();
    long time = now.getTime();
    long timeDiff = LOCATION_MAX_AGE;
    for (int i=providers.size()-1; i>=0; i--) {
        Location l = locationManager.getLastKnownLocation(providers.get(i));
        if (l != null) {
            long t = l.getTime();
            if (time - t < timeDiff) {
                myLocation = l;
                time = t;
                timeDiff = time - t;
            }
        }
    }
    // if failed to get cached location or if it is older than 2 hours, request GPS position
    if (myLocation == null) {
        if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
            pIntent = PendingIntent.getBroadcast(context,
                    0,
                    new Intent(SINGLE_UPDATE_ACTION),
                    PendingIntent.FLAG_UPDATE_CURRENT);

            IntentFilter iFilter = new IntentFilter(SINGLE_UPDATE_ACTION);
            receiver = new BroadcastReceiver() {
                @Override
                public void onReceive(Context context, Intent intent) {
                    // when received an answer from the LocationManager
                    Location gpsLocation = (Location) intent.getExtras().get(LocationManager.KEY_LOCATION_CHANGED);
                    fillLocation(gpsLocation);
                    Log.d(TAG, "Received GPS location: " + gpsLocation.getLatitude() + ", " + gpsLocation.getLongitude() + " Time: " + gpsLocation.getTime());
                    locationManager.removeUpdates(pIntent);
                    unregisterReceiver(receiver);
                }
            };
            context.registerReceiver(receiver, iFilter);
            // I'm absolutely fine with getting the first available GPS position and that's enough to me.
            locationManager.requestSingleUpdate(LocationManager.GPS_PROVIDER, pIntent);
         // if GPS is disabled in settings allow user to enable it
        } else {
            showGPSDisabledAlertToUser();
        }
    } else {
        // if fresh enough lastKnownLocation is found
        fillLocation(myLocation);
    }
}

Answer 1

我建议您使用ProgressDialog来通知正在等待修复的用户。您还可以设置消息并向其添加cancel按钮。查看此链接：如何设置取消按钮在进行对话框？

如果用户取消ProgressDialod，那么您将以手动输入请求启动屏幕。

问候。