关于android-beacon-library's scan-period的问题

Question

我在使用 android-beacon-library 时遇到有关扫描周期的问题。这是我的问题：

我有三个主要 class：MainActivity、BaseService 和 BeaconService。

MainActivity：只做startForeground和stopForeground运算。
BaseService：做一些参数初始化，BeaconManager等等。
BeaconService: 信标操作。

我先描述我的问题。我正在使用前台服务进行扫描操作，backgroundScanPeriod 是 20l。我还有一个带有两个按钮的 MainActivity，startService 和 stopService。当我第一次打开应用程序并单击 startService 时，扫描周期为 10s。

然后我单击“主页”并关闭此应用程序，服务运行正常，扫描周期也为 10 秒。但是当我通过点击图片上的通知重新打开 MainActivity 时。

扫描周期将变为1s。这对我来说很快。但是，如果我再次单击“主页”，扫描周期就会变得正常。这意味着，除了第一次打开 MainActivity 之外，每次扫描周期都会变得非常快。

我想知道为什么。下面是我的重要代码：

MainActivity.class

@OnClick(R.id.start_service)
void start_Service() {
    if (Utils.isServiceRunning(MainActivity.this, Constants.CLASSNAME)) {
        Toast.makeText(this, "service is running, don't start again", Toast.LENGTH_SHORT).show();
    } else {
        Intent intent = new Intent(MainActivity.this, BeaconService.class);
        intent.setAction(Constants.ACTION.STARTFOREGROUND_ACTION);
        startService(intent);
        setInfo();
    }
}

@OnClick(R.id.stop_service)
void stop_Service() {
    if (Utils.isServiceRunning(MainActivity.this, Constants.CLASSNAME)) {
        Intent intent = new Intent(MainActivity.this, BeaconService.class);
        intent.setAction(Constants.ACTION.STOPFOREGROUND_ACTION);
        startService(intent);
        setInfo();
    } else {
        Toast.makeText(this, "service is dead, don't kill again", Toast.LENGTH_SHORT).show();
    }
}

BaseService.class

private void setBeaconManager() {
    beaconManager.setBackgroundBetweenScanPeriod(20l);
    beaconManager.setBackgroundMode(true);
    beaconManager.getBeaconParsers().clear();
    beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout(Constants.BEACON_LAYOUT.COMMON_LAYOUT));
}

BeaconService.class

public class BeaconService extends BaseService implements BootstrapNotifier, BeaconConsumer {
private static final int NOTIFICATION = R.string.notify_service_started;
private static final String TAG = "BeaconService";

private int size = -1;

private RegionBootstrap regionBootstrap;

private BackgroundPowerSaver backgroundPowerSaver;

private Beacon beacon;

@Nullable
@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate() {
    super.onCreate();
    Log.d(TAG, "onCreate");

    regionBootstrap = new RegionBootstrap(this, region);

    beaconManager.bind(this);

    backgroundPowerSaver = new BackgroundPowerSaver(getApplicationContext());
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    if (intent != null && intent.getAction() != null) {
        switch (intent.getAction()) {
            case Constants.ACTION.STARTFOREGROUND_ACTION:
                startForeground(NOTIFICATION, getNotification());
                break;
            case Constants.ACTION.STOPFOREGROUND_ACTION:
                Log.d(TAG, "Received stop foreground request");
                stopForeground(true);
                stopSelf();
                break;
        }
    }

    return START_STICKY;
}

@Override
public void onDestroy() {
    beaconManager.unbind(this);
    regionBootstrap.disable();
    Log.d(TAG, "service onDestroy");
}

/**
 * Called when at least one beacon in a Region is visible.
 *
 * @param region region
 */
@Override
public void didEnterRegion(Region region) {
    // TODO: 3/8/16 reload all the resource
    Log.d(TAG, "didEnterRegion called");
    L.object(region);
    try {
        beaconManager.startRangingBeaconsInRegion(region);
    } catch (RemoteException e) {
        e.printStackTrace();
    }
}

/**
 * Called when no beacons in a Region are visible.
 *
 * @param region region
 */
@Override
public void didExitRegion(Region region) {
    // TODO: 3/8/16 close all the resource
    Log.d(TAG, "didExitRegion called");
    try {
        beaconManager.stopRangingBeaconsInRegion(region);
    } catch (RemoteException e) {
        e.printStackTrace();
    }
    beaconManager.unbind(this);
    regionBootstrap.disable();
    L.object(region);
}

/**
 * Called with a state value of MonitorNotifier.INSIDE when at least one beacon in a Region is visible
 *
 * @param region region
 */
@Override
public void didDetermineStateForRegion(int i, Region region) {
    Log.d(TAG, "switch from seeing/not seeing beacons");
    L.object(region);
}

@Override
public void onBeaconServiceConnect() {
    Log.d(TAG, "onBeaconServiceConnect");
    if (null == beaconManager.getRangingNotifier()) {
        beaconManager.setRangeNotifier(new RangeNotifier() {
            @Override
            public void didRangeBeaconsInRegion(Collection<Beacon> beacons, Region region) {
                Log.d(TAG, "beacons.size():" + beacons.size() + "," + this);
                if (beacons.size() != 0) {
                    Iterator<Beacon> iterator = beacons.iterator();
                    if (beacons.size() != size) {
                        saveBeacon(iterator);
                        size = beacons.size();
                    }
                }
            }
        });
    }
}

/**
 * Save beacon p-o-j-o to SQLite.
 */
private void saveBeacon(Iterator<Beacon> iterator) {
    while (iterator.hasNext()) {
        beacon = iterator.next();
        L.object(beacon);
        entity.setId(null);
        entity.setUuid(beacon.getId1().toString());
        entity.setMajor(beacon.getId2().toString());
        entity.setMinor(beacon.getId3().toString());
        entity.setTxpower(beacon.getTxPower());
        entity.setTime(Utils.getCurrentTime());

        dbHelper.provideNinjaDao().insert(entity);
        Log.d(TAG, "sql save success");
    }
}

private Notification getNotification() {
    CharSequence text = getText(R.string.notify_service_started);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);
    Notification notification = new Notification.Builder(this)
            .setSmallIcon(R.mipmap.ninja_turtle)
            .setTicker(text)
            .setWhen(System.currentTimeMillis())
            .setContentTitle(getText(R.string.info_service))
            .setContentText(text)
            .setContentIntent(contentIntent)
            .build();

    return notification;
}
}

希望大家能帮帮我。提前致谢。

Answer 1

几点：

使用 Android 信标库有两组不同的扫描周期设置，前景和背景。当使用代码中的BackgroundPowerSaver时，Android信标库会自动在前台扫描周期和后台扫描周期之间来回切换。
当使用 BackgroundPowerSaver 时，手动设置 beaconManager.setBackgroundMode(true) 只会在下次应用程序循环到前台之前有效 - BackgroundPowerSaver 将自动更改此设置的值。
扫描周期的单位是毫秒。所以设置 beaconManager.setBackgroundBetweenScanPeriod(20l); 将扫描周期设置为 20 毫秒。这太短了，无法可靠地拾取信标。我建议最小扫描周期为 1100 毫秒。周期越长，检测到信标的概率越高，但使用的电池越多。
如果你想在扫描之间等待10秒，你要设置：beaconManager.setBackgroundBetweenScanPeriod(10000l); // 10000 ms = 10.0 secs

如果您希望在前台和后台应用相同的扫描周期，只需将它们设置为相同即可：

 beaconManager.setBackgroundBetweenScanPeriod(10000l);
 beaconManager.setForegroundBetweenScanPeriod(10000l);
 beaconManager.setBackgroundScanPeriod(1100l);
 beaconManager.setForegroundScanPeriod(1100l);

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