Question

我已经设置了LocationManager以每2分钟获取当前位置：

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 120000, 0, this);

这很好用，onLocationChanged按预期每2分钟调用一次。但是，似乎在每隔 2分钟的10-40（随机量）第二跨度中多次调用它。我记录了onLocationChanged中收到的每个位置，所以这里有一些示例来了解发生了什么：

17:30

GPS 32.0 50.66318929195404 10.735434293746948 0.0 2010.08.07 17:30:10 GPS 32.0 50.66315710544586 10.735423564910889 0.0 2010.08.07 17:30:14 GPS 32.0 50.66314101219177 10.735418200492859 0.0 2010.08.07 17:30:17 GPS 32.0 50.66314101219177 10.735418200492859 0.0 2010.08.07 17:30:20 GPS 24.0 50.66313564777374 10.735418200492859 0.5 2010.08.07 17:30:24 GPS 32.0 50.663098096847534 10.735573768615723 0.0 2010.08.07 17:30:28 GPS 32.0 50.663065910339355 10.735611319541931 0.0 2010.08.07 17:30:31

然后我在2分钟内没有更新。

17:32

GPS 32.0 50.661821365356445 10.737022161483765 1.0 2010.08.07 17:32:39 GPS 16.0 50.66170871257782 10.737043619155884 1.8200275 2010.08.07 17:32:45 GPS 24.0 50.661579966545105 10.737027525901794 1.25 2010.08.07 17:32:50 GPS 16.0 50.66150486469269 10.73712408542633 1.0 2010.08.07 17:32:55 GPS 12.0 50.661579966545105 10.73715090751648 0.9013878 2010.08.07 17:33:01 GPS 24.0 50.66139221191406 10.737038254737854 1.5811388 2010.08.07 17:33:06 GPS 16.0 50.66141366958618 10.737301111221313 0.70710677 2010.08.07 17:33:12 GPS 16.0 50.66141366958618 10.737301111221313 0.70710677 2010.08.07 17:33:12 GPS 24.0 50.661311745643616 10.737070441246033 1.118034 2010.08.07 17:33:16 GPS 16.0 50.66122591495514 10.737177729606628 1.118034 2010.08.07 17:33:22 GPS 12.0 50.66124200820923 10.737220644950867 1.3462912 2010.08.07 17:33:26 GPS 12.0 50.661311745643616 10.737268924713135 3.6055512 2010.08.07 17:33:25

等等......然后在2分钟后的17:35进行另一组更新。

这是标准行为吗？我期望每2分钟只获得一个位置，并且它给我位置更新的时间跨度似乎相当随机。理想情况下，我宁愿只获得一个位置......有没有办法做到这一点？

Answer 1

来自requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)陈述minTime参数的文档：

“通知的最短时间间隔，以毫秒为单位。此字段仅用作节省电量的提示，位置更新之间的实际时间可能大于或小于此值。”

所以问题的答案是肯定的，这是标准行为，不，你不能改变它。

如果这对您来说是个问题，如果还没有经过一定的时间，您可以忽略对回调方法的调用。

Answer 2

我发现了这个问题，因为我遇到了同样的问题。

我相信我有答案。由于您将meter参数设置为0，因此正在触发快速更新。

将米参数更改为10，如果您的位置更改10或更多，它将每2分钟触发一次LocationChanged事件。

在我做这个更改之前，LocationChanged每秒都会多次触发。现在，它发射一次。然后每隔2分钟，您会在状态栏上看到GPS图标，但除非您的位置发生变化，否则事件不会触发。

我希望这会有所帮助。这就是为我解决的问题。没有必要添加任何额外的逻辑来防止虚假火灾。

Answer 3

这是我的LocationListener实现，用于过滤掉不必要的onLocationChanged（）事件：

注意我在我的服务中使用消息。

public class GPSlocationListener implements LocationListener 
{
    //member variables
    private Handler mParentHandler;//points to Handler of parent
    private long mTimeBetweenLocationEvents;
    private long mTimeOfLastLocationEvent;
    private boolean mAccuracyOverride;
    private float mLastAccuracy;
    private boolean mOverrideLocation;

    //constants
    private static final float INVALID_ACCURACY = 999999.0f;
    private static final String TAG = "GPSlocationListener";


    //constructor
    public GPSlocationListener(Handler parentMsgHandler, long timeBetweenLocationEvents, boolean accuracyOverride)
    {
        mParentHandler = parentMsgHandler;
        mTimeOfLastLocationEvent = 0;
        mAccuracyOverride = accuracyOverride;
        mLastAccuracy = INVALID_ACCURACY;
        mOverrideLocation = false;
        mTimeBetweenLocationEvents = timeBetweenLocationEvents;
    }

    //EVENT: onLocationChanged()
    // send GPS coordinates to CommService
    public void onLocationChanged(Location loc)
    {
        Log.d(TAG, "onLocationChanged() triggered. Accuracy = "+Float.toString(loc.getAccuracy()));
        mOverrideLocation = false;

        if (loc != null)
        {
            //if a more accurate coordinate is available within a set of events, then use it (if enabled by programmer)
            if (mAccuracyOverride == true)
            {
                //whenever the expected time period is reached invalidate the last known accuracy
                // so that we don't just receive better and better accuracy and eventually risk receiving
                // only minimal locations
                if (loc.getTime() - mTimeOfLastLocationEvent >= mTimeBetweenLocationEvents)
                {
                    mLastAccuracy = INVALID_ACCURACY;
                }


                if (loc.hasAccuracy())
                {
                    final float fCurrentAccuracy = loc.getAccuracy();

                    //the '<' is important here to filter out equal accuracies !
                    if ((fCurrentAccuracy != 0.0f) && (fCurrentAccuracy < mLastAccuracy))
                    {
                        mOverrideLocation = true;
                        mLastAccuracy = fCurrentAccuracy;
                    }
                }
            }

            //ensure that we don't get a lot of events
            // or if enabled, only get more accurate events within mTimeBetweenLocationEvents
            if (  (loc.getTime() - mTimeOfLastLocationEvent >= mTimeBetweenLocationEvents)
                ||(mOverrideLocation == true) )
            {
                //be sure to store the time of receiving this event !
                mTimeOfLastLocationEvent = loc.getTime();

                //send message to parent containing the location object
                Message msgToMain = mParentHandler.obtainMessage();
                msgToMain.what = Constants.MSG_LOCATION_CHANGED;
                msgToMain.obj = loc;
                mParentHandler.sendMessage(msgToMain);
            }
        }
    }

    public void onProviderDisabled(String provider)
    {
        // TODO Auto-generated method stub
    }

    public void onProviderEnabled(String provider)
    {
        // TODO Auto-generated method stub
    }

    public void onStatusChanged(String provider, int status, Bundle extras)
    {
        // TODO Auto-generated method stub
    }

}

这在主代码中实现如下：

//create the APIthread (which exposes mAPIhandler back to this service)
mAPIthread = new APIthread(mApiHandler);
mAPIthread.start();


//use the LocationManager class to obtain GPS locations
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);    

locationListener = new GPSlocationListener(mApiHandler, Constants.LOCATION_UPDATE_PERIOD_MSEC, true);

//this will call GPSlocationListener.onLocationChanged()
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 
                                       //3 mins NOTE: approximate value
                                       Constants.LOCATION_UPDATE_PERIOD_MSEC,
                                       //no distance updates desired
                                           0,
                                           locationListener);

LocationManager经常调用onLocationChanged？

3 个答案: