在后台模式android 11下，蓝牙不会扫描附近的设备

Question

我尝试在后台模式下扫描附近的蓝牙设备，它在android 11等某些设备上不起作用。

这是我的示例代码，在前台工作得很好

//已授予所有权限

 <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
 <!--BLUETOOTH PERMISSION-->
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <!-- Needed only if your app looks for Bluetooth devices.
             If your app doesn't use Bluetooth scan results to derive physical
             location information, you can strongly assert that your app
             doesn't derive physical location. -->
    <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
    <!-- Needed only if your app makes the device discoverable to Bluetooth
      devices. -->
    <uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />
    <!-- Needed only if your app communicates with already-paired Bluetooth
           devices. -->
    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <!--bibo01 : hardware option-->
    <uses-feature android:name="android.hardware.bluetooth" android:required="false"/>
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="false"/>

//用于扫描api版本在21以上的Ble设备

private var settings: ScanSettings?         = null
private val scanFilters = java.util.ArrayList<ScanFilter>()
private var mLEScanner: BluetoothLeScanner? = null
private var adapter: BluetoothAdapter?        = null




    val adapterBlu = applicationContextNew.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
    adapter = adapterBlu.adapter

    mLEScanner = adapter!!.bluetoothLeScanner
    settings   = ScanSettings.Builder()
        //.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
        .build()
    //scan specified devices only with ScanFilter
    val scanFilter = ScanFilter.Builder()
        //.setDeviceName("BIBO 1")
        .build()
    scanFilters.add(scanFilter)



  mLEScanner = adapter!!.bluetoothLeScanner
    settings   = ScanSettings.Builder()
        .build()
    //scan specified devices only with ScanFilter
    val scanFilter = ScanFilter.Builder()
        .build()
    scanFilters.add(scanFilter)

//扫描：

 mLEScanner!!.startScan(scanFilters, settings, highScanCallback)


//high Scan callback
private val highScanCallbackClackmass =
    object : ScanCallback() {
        override fun onScanResult(callbackType: Int, result: ScanResult) {

            
            if (result.device.name != null && result.device.address != null){
                if ("BIBO 1" == result.device.name.toString()) {
                    //globalDeviceAddress = result.device.address.toString()
                }
            }

        }
    }

还尝试了屏幕唤醒解决方案：（在android 10以下工作）

val pm: PowerManager = getSystemService(POWER_SERVICE) as PowerManager
                val isScreenOn: Boolean = pm.isInteractive // check if screen is on
                if (!isScreenOn) {
                    val wl: PowerManager.WakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK or PowerManager.ACQUIRE_CAUSES_WAKEUP, "myApp:notificationLock")
                    wl.acquire(9000) //set your time in milliseconds
                }

Answer 1

电池限制也会影响BLE在后台的工作（在我的设备上注意到了，但当时是Android 10）。

背景=

在我的例子中，这是在dislay关闭时进行应用程序扫描所必需的。

Answer 2

您还需要添加ACCESS\u rough\u LOCATION和ACCESS\u FINE\u LOCATION权限。有关更多信息，请查看以下链接：-

• 需要为Android 6.0上的BLE扫描启用位置
• 需要为Android 10.0上的BLE扫描启用位置
• 在未经用户许可的情况下打开Android LE扫描
• 蓝牙扫描仪未发现设备
• Android BLE开发终极指南