禁用蓝牙识别Android / Kotlin上的BLE设备

Question

I am developing a solution to check BLE devices and I used the native API that comes with Android to check BluetoothLeScanner.

Wanted to understand a little better operation, I take the location permission and bluetooth.

After the scan starts, I turn Bluetooth on my phone to off, on Moto G2 Android 6.0 Scan still keeps giving me the expected result when I test on a Samsung S8 Android 9 and Sony Xperia T2 Ultra Android 5.1 in the log I get which was bluetooth disabled and the scan was stopped.

I can only perform the test when I purchase it as follows

 bluetoothManager = getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
 bluetoothAdapter = bluetoothManager.adapter

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            bluetoothScanner = bluetoothAdapter.bluetoothLeScanner
        }

@TargetApi(Build.VERSION_CODES.M)
    class BleScanCallback(resultMap: MutableMap) : ScanCallback() {


    var resultOfScan = resultMap

    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    @TargetApi(Build.VERSION_CODES.M)
    override fun onScanResult(callbackType: Int, result: ScanResult?) {
        addScanResult(result)
        Log.v("Main Activity", "I found a ble device ${result}")
        Log.v("Main Activity", "I found a ble device ${result?.device?.address}")

    }

    override fun onBatchScanResults(results: MutableList<ScanResult>?) {
        results?.forEach { result -> addScanResult(result) }
    }

    override fun onScanFailed(errorCode: Int) {
        Log.v("Main Activity","Bluetooth LE scan failed. Error code: $errorCode")
    }

    fun addScanResult(scanResult: ScanResult?) {
        val bleDevice = scanResult?.device
        val deviceAddress = bleDevice?.address
        resultOfScan.put(deviceAddress, bleDevice)
    }

scanResult is bringing the necessary information when bluetooth is online, I already set it up as the image below

https://i.stack.imgur.com/o9jGRm.png

I see that this makes scanning even off

Answer 1

There is no way to detect BLE devices with bluetooth off

Bluetooth must be enabled

Set up BLE

Before your application can communicate over BLE, you need to verify that BLE is supported on the device, and if so, ensure that it is enabled.

Answer 2

On some Android devices including Pixel phones, Android One devices, and unmodified AOSP builds, turning off bluetooth in the quick settings panel doesn't really turn off bluetooth. Instead, it merely blocks bluetooth connections and pairing in software, yet allows Bluetooth LE scans to continue unaffected. As @Jorgesys correctly notes, it is impossible to detect BLE devices if the Bluetooth radio is really turned off, so let me say again: despite what the quick settings panel says, bluetooth is not necessarily powered off.

On supported devices, this happens only if two things are true:

1. Bluetooth is turned on in the full settings menu (On Android 9: Settings -> Connected Devices -> Connection preferences -> Bluetooth ON)
2. The user has selected to "Allow apps and services to scan for nearby devices at any time, even when Bluetooth is off. This can be used, for example, to improve location-based features and services." (Settings -> Security & Location -> Location -> Advanced -> Scanning -> Bluetooth scanning ON)