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android - Kotlin 我对 BLE ScanCallback 有问题

问题描述

@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    private fun discover(){
        val mBluetoothLeScanner: BluetoothLeScanner =BluetoothAdapter.getDefaultAdapter().bluetoothLeScanner
        val mHandler: Handler = Handler()
        val scanCallback = object:ScanCallback() {
            override fun onScanResult(callbackType: Int, result: ScanResult?) {
                Log.d(TAG, "onscanresult...")
                super.onScanResult(callbackType, result)

                if (result == null || result.getDevice() == null || TextUtils.isEmpty(result.getDevice().getName())
                ) return

                val builder = StringBuilder(result.getDevice().getName())
                builder.append("\n").append(
                    result.getScanRecord()
                        ?.getServiceData(result.getScanRecord()!!.getServiceUuids().get(0)),
                    Charset.forName("UTF-8")
                )
                //Observed result
                Log.d(TAG, builder.toString())
            }

            override fun onBatchScanResults(results:List<ScanResult>?){
                Log.d(TAG, "Scanning...")
                super.onBatchScanResults(results)
            }

            override fun onScanFailed(errorCode: Int) {
                Log.d(TAG, "Discovery onScanFailed: $errorCode")
                super.onScanFailed(errorCode)
            }
        }

        val filters: ArrayList<ScanFilter> = ArrayList<ScanFilter>()
        val uuid = UUID.randomUUID()
        val filter: ScanFilter = ScanFilter.Builder().setServiceUuid(ParcelUuid(UUID.fromString("uuid"))).build()
        filters.add(filter)
        val settings: ScanSettings = ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY).build()
        mBluetoothLeScanner?.startScan(filters, settings, scanCallback)
        Log.d(TAG, "StartScan...")
        mHandler.postDelayed(object : Runnable {
            override fun run() {
                mBluetoothLeScanner?.stopScan(scanCallback)
            }
        }, 10000)
        finish()
    }

在上面的代码中，我实现了 BLE 扫描来接收字符串。但是，似乎 scanCallback 有问题，但我不确定它是什么。在 Logcat 上，它显示“Startscan ...”，但没有显示“onscanresult ...”，所以我认为问题出在 scanCallback 上。可能是什么原因？？此代码是基于https://code.tutsplus.com/tutorials/how-to-advertise-android-as-a-bluetooth-le-peripheral--cms-25426编写的，但由于示例是在 Java 中，我我自己在 Kotlin 上实现了。

标签： androidkotlinbluetooth-lowenergy

解决方案

您可以尝试像这样将 null 发送到 startScan

mBluetoothLeScanner?.startScan(null, settings, scanCallback)

请参阅它说的ScanFilter 文档

从蓝牙 LE 扫描过滤结果的标准。ScanFilter 允许客户端将扫描结果限制在他们感兴趣的范围内。

因此，我认为当您设置过滤器时，它会根据您的标准过滤来自 onScanResult 的结果。尝试删除它，如果它有效，则问题在于您的过滤条件，您应该尝试调试它。也许您正在寻找的设备发送的服务 ID 是错误的。

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