android - 如何重启BluetoothLeScanner？

Question

我正在使用 Android 端的 BluetoothLeScanner 将 Android 设备连接到 iOS。这一切都是第一次完美运行。

问题是，在我连接到其中一个已发现的 iOS 设备后，我停止了扫描 (stopScan(scanCallback)) 以保存能量。

如果之前连接的设备由于某种原因断开连接，我会再次开始扫描...但似乎在“重新启动”扫描后不再工作 - 它不会发现更多设备...不知道为什么但我'被迫重启应用程序。

有什么办法解决这个问题吗？

我还使用 ScanFilter 按 UUID 过滤设备，并使用 ScanSettings.SCAN_MODE_BALANCED 作为扫描模式。

代码如下:

private void startScanner() {
    BluetoothManager bluetoothManager = (BluetoothManager) activity.getSystemService(activity.BLUETOOTH_SERVICE);
    BluetoothAdapter adapter = bluetoothManager.getAdapter();
    scanner = adapter.getBluetoothLeScanner();
    ScanSettings settings = new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_BALANCED).build();
    scanner.startScan(scanFilters(), settings, scanCallback);
    System.out.println("Scanner started");
}

private List<ScanFilter> scanFilters() {
    ScanFilter filter = new ScanFilter.Builder().setServiceUuid(THE_BT_UUID).build();
    List<ScanFilter> list = new ArrayList<ScanFilter>(1);
    list.add(filter);
    return list;
}



private final ScanCallback scanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        BluetoothDevice device = result.getDevice();
        if (device != null) {
            callback.foundRemoteDevice(BluetoothCentral.this, device);
        }
    }
}


public void connectToDevice(BluetoothDevice device) {
    if (gatt == null) {
        gatt = device.connectGatt(activity, false, gattCallback);
        scanner.stopScan(scanCallback);
    }
}


private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        System.out.println("onConnectionStateChange; status: " + status + ", state: " + newState);

        switch (newState) {
            case BluetoothProfile.STATE_CONNECTED:
                System.out.println("STATE_CONNECTED");
                if (!startedServiceDiscovery) {
                    gatt.discoverServices();
                    startedServiceDiscovery = true;
                }
                break;
            case BluetoothProfile.STATE_DISCONNECTED:
                callback.didDisconnectFromDevice(BluetoothCentral.this, gatt.getDevice());
                gatt = null;
                startScanner();
                break;
            default:
                System.out.println("STATE_OTHER");
        }

    }
}

请注意，我在调用 connectGatt 后立即停止扫描器，并在收到 BluetoothProfile.STATE_DISCONNECTED 回调时再次启动它。

Answer 1

作为我的评论，帮助您解决了问题，我在这里添加我的评论作为答案。

Code seems ok to me, did you try adding logs in onScanResult method. to check if device is getting detected but something else is failing. One more thing, I see if I restart scanning it takes time to get the device detected in comparison of first scanning.