Android 7.0 ble扫描没有结果

Question

当我开始ble(蓝牙Le)扫描几秒钟,然后停止扫描.然后启动,然后停止......大约5-8次循环后,启动动作将无效,这意味着无法接收扫描记录.1.此条件仅出现在Android 7.0或更高版本(7.1.1); 2.我尝试了两种扫描方法:BluetoothAdapter.startLeScan()和Scanner.startScan(),没有区别.

private void scanToggle(final boolean enable) {
    mScanHandler.removeCallbacks(scanTask);
    if (enable) {
        TelinkLog.i("ADV#scanner#startScan");
        scanner = mBluetoothAdapter.getBluetoothLeScanner();
        scanner.startScan(null, settings, scanCallback);
        mScanning = true;
        mDeviceList.clear();
        mListAdapter.notifyDataSetChanged();
       //mBluetoothAdapter.startLeScan(leScanCallback);
        mScanHandler.postDelayed(scanTask, SCAN_PERIOD);
    } else {
        TelinkLog.i("ADV#scanToggle#stopScan");
        mScanning = false;
        //mBluetoothAdapter.stopLeScan(leScanCallback);
        scanner.stopScan(scanCallback);
    }
    invalidateOptionsMenu();
}


private BluetoothAdapter.LeScanCallback leScanCallback = new BluetoothAdapter.LeScanCallback() {
    @Override
    public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
        TelinkLog.d("scan:" + device.getName());
        for (AdvDevice advDevice : mDeviceList) {
            if (device.getAddress().equals(advDevice.device.getAddress())) return;
        }
        mDeviceList.add(new AdvDevice(device, rssi, scanRecord));
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mListAdapter.notifyDataSetChanged();
            }
        });
    }
};

private ScanCallback scanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        super.onScanResult(callbackType, result);
        for (AdvDevice advDevice : mDeviceList) {
            if (result.getDevice().getAddress().equals(advDevice.device.getAddress())) return;
        }
        mDeviceList.add(new AdvDevice(result.getDevice(), result.getRssi(), result.getScanRecord().getBytes()));
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mListAdapter.notifyDataSetChanged();
            }
        });
    }

    @Override
    public void onBatchScanResults(List<ScanResult> results) {
        super.onBatchScanResults(results);
    }

    @Override
    public void onScanFailed(int errorCode) {
        super.onScanFailed(errorCode);
    }
};

Answer 1

您可能会遇到Android 7中新的和未记录的行为更改,这些更改会阻止应用程序过于频繁地扫描.

我写了一篇关于它的博客文章:https: //blog.classycode.com/undocumented-android-7-ble-behavior-changes-d1a9bd87d983

Answer 2

我也遇到过这样的问题。通过启用位置即可解决。在android中，我们需要启用位置扫描附近的设备。所以请检查位置是否启用。下面的代码很有用。我希望它能起作用，就我而言，效果很好。

LocationManager manager = (LocationManager) mainActivity.getSystemService(Context.LOCATION_SERVICE);
if (!manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
    buildAlertMessageNoGps(mainActivity);
}else{ //scanning part}


public void  buildAlertMessageNoGps(MainActivity mainActivity){
    final AlertDialog.Builder builder = new AlertDialog.Builder(mainActivity);
    builder.setMessage("Your GPS seems to be disabled, do you want to enable it? It is required for this application.")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(final DialogInterface dialog, final int id) {
                    mainActivity.startActivityForResult(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS), MainActivity.LOCATION_ENABLE);
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(final DialogInterface dialog, final int id) {
                    dialog.cancel();
                    mainActivity.finishAffinity();
                }
            });
    final AlertDialog alert = builder.create();
    alert.show();
}

到达位置后开始扫描并获取扫描结果。