Kotlin 我有 BLE ScanCallback 的问题

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，我已经实现了 BLE 扫描来接收一个字符串。但是，似乎 scanCallback 有问题，但我不确定是什么问题。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，但由于示例是用 Java 编写的，因此我自己在 Kotlin 上实现了。

解决方法

你可以尝试像这样发送 null 到 startScan

mBluetoothLeScanner?.startScan(null,settings,scanCallback)

参考ScanFilter doc它说

用于过滤低功耗蓝牙扫描结果的标准。 ScanFilter 允许客户端将扫描结果限制为仅对他们感兴趣的结果。

所以我认为当您设置过滤器时，它会根据您的条件过滤结果到 onScanResult 。尝试删除它，如果它有效，那么问题在于您的过滤标准，您应该尝试对其进行调试。可能您要查找的设备发送的服务 ID 有误。

android android bluetooth-lowenergy ko