我正在使用altbeacon库进行BLE扫描，在Android O +上，BLE处于前台模式，所有其他Android O之前的设备都在后台运行。扫描开始没问题，在某些情况下，另一个后台作业会改变扫描周期，执行代码后，我看到设置已应用，但是我看不到扫描速度降低。
这是我用来刷新扫描速率的代码（在BLE激活并扫描之后）：
public static int SHORT_SCAN_PERIOD = 2 * 1000;
public static int SHORT_BETTWEEN_SCAN_PERIOD = 4 * 1000;
public static int LONG_BETWEEN_SCAN_PERIOD = 3600 * 1000;
private void refreshBLEScanPeriod() {
BeaconManager beaconManager = BeaconManager.getInstanceForApplication(getApplicationContext());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
Log.d(logTag, "Refreshing BLE scan period");
//beaconManager.setForegroundScanPeriod(Config.SHORT_SCAN_PERIOD);
beaconManager.setForegroundBetweenScanPeriod(Config.SHORT_BETTWEEN_SCAN_PERIOD);
} else {
//beaconManager.setBackgroundScanPeriod(Config.SHORT_SCAN_PERIOD);
beaconManager.setBackgroundBetweenScanPeriod(Config.SHORT_BETTWEEN_SCAN_PERIOD);
}
try {
beaconManager.applySettings();
beaconManager.updateScanPeriods();
Log.d(logTag, "BLE scan period updated to SHORT");
AppDefaultNotification appDefaultNotification = new AppDefaultNotification(getApplicationContext());
appDefaultNotification.buildNotification();
} catch (RemoteException e) {
Log.e(logTag, "Unable to reset scan period " + e.getMessage());
}
}
这是我启动BLE的代码：
beaconScanner = BeaconScanner.getInstance(getApplicationContext());
beaconManager = BeaconManager.getInstanceForApplication(this);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
appDefaultNotification = new AppDefaultNotification(this);
Log.d(logTag, "starting BLE foreground service");
beaconManager.setForegroundScanPeriod(Config.SHORT_SCAN_PERIOD);
beaconManager.setForegroundBetweenScanPeriod(Config.SHORT_BETTWEEN_SCAN_PERIOD);
/**
* For the above foreground scanning service to be useful, you need to disable
* JobScheduler-based scans (used on Android 8+) and set a fast background scan
* cycle that would otherwise be disallowed by the operating system.
*/
beaconManager.setEnableScheduledScanJobs(false);
beaconManager.setBackgroundBetweenScanPeriod(0);
beaconManager.setBackgroundScanPeriod(1100);
beaconManager.enableForegroundServiceScanning(appDefaultNotification.buildNotification(), Constants.NOTIFICATION_ID.FOREGROUND_SERVICE);
} else {
beaconManager.setEnableScheduledScanJobs(false);
/**
* Every 60s scan for 20s
*/
// set the duration of the scan to be 1.1 seconds
beaconManager.setBackgroundScanPeriod(Config.SHORT_SCAN_PERIOD);
// set the time between each scan to be 30 seconds
beaconManager.setBackgroundBetweenScanPeriod(Config.SHORT_BETTWEEN_SCAN_PERIOD);
setBackgroundBetweenScanPeriod(sharedPreferences.getInt(Config.KEY_BLE_BETWEEN_SCAN_PERIOD, Config.SHORT_BACKGROUND_BETWEEN_SCAN_PERIOD));
}
/**
* simply constructing this class and holding a reference to it in your custom Application
* class will automatically cause the BeaconLibrary to save battery whenever the application
* is not visible. This reduces bluetooth power usage by about 60%
*/
backgroundPowerSaver = new BackgroundPowerSaver(this);
beaconManager.getBeaconParsers().clear();
beaconManager.getBeaconParsers().add(new BeaconParser().
setBeaconLayout("m:2-3=0215,i:4-19,i:20-21,i:22-23,p:24-24")); // iBeacon Layout
这是日志：
09-21 22：00：36.594 5776-5949：BeaconManager在修改扫描之前 周期，扫描周期4000之间的beaconMgr
09-21 22：00：36.594 5776-5949：BeaconManager刷新BLE扫描周期 到长
09-21 22：00：36.595 5776-5949：BeaconManager BLE扫描周期已更新
09-21 22：00：36.689 5776-5949：BeaconManager当前beaconMgr 扫描周期3600000
这是长时间显示的BLE仍在积极扫描：
09-21 22：03：59.821 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '45 .70308117629712}
09-21 22：03：59.827 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '45 .70308117629712}
09-21 22：04：00.960 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '47 .328112013435565}
09-21 22：04：00.965 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '47 .328112013435565}
09-21 22：04：02.082 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '47 .88079569698942}
09-21 22：04：02.086 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '47 .88079569698942}
09-21 22：04：03.225 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：04：03.232 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：04：05.462 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '49 .57251774840043}
09-21 22：04：05.467 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '49 .57251774840043}
09-21 22：04：59.948 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：04：59.956 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：05：01.073 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '56 .22605173071153}
09-21 22：05：01.083 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '56 .22605173071153}
09-21 22：05：15.786 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：05：15.794 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '49 .0029516131644}
09-21 22：05：18.031 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '50 .7288634831964}
09-21 22：05：18.036 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '50 .7288634831964}
09-21 22：05：20.267 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '56 .22605173071153}
09-21 22：05：20.272 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '56 .22605173071153}
09-21 22：05：21.400 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '50 .7288634831964}
09-21 22：05：21.404 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '50 .7288634831964}
09-21 22：05：22.528 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '45 .70308117629712}
09-21 22：05：22.533 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '45 .70308117629712}
09-21 22：05：23.657 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '44 .126620660525674}
09-21 22：05：23.661 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '44 .126620660525674}
09-21 22：05：24.772 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '43 .465561542707945}
09-21 22：05：24.773 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，distance = '43 .465561542707945}
09-21 22：05：28.180 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '44 .51624911719877}
09-21 22：05：28.189 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '44 .51624911719877}
09-21 22：05：34.975 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '43 .985672374000856}
09-21 22：05：34.977 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '43 .985672374000856}
09-21 22：05：36.107 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '43 .20355217003139}
09-21 22：05：36.112 5776-5776：检测到信标 BeaconSignal {uuid ='50765cb7-d9ea-4e21-99a4-fa879613a492'， major ='52259'，minor ='29402'，距离= '43 .20355217003139}