android - 如何在 Android 中为 BLE 设备设置蜂鸣器

Question

我开发了 Android 应用程序来使用 BLE 设备进行操作，如图所示 image .

该应用程序可以扫描并连接设备，但我无法编写正确的特征来使标签蜂鸣。我写这段代码来做到这一点:

private static final int ALERT_HIGH = 2;
private static final UUID IMMEDIATE_ALERT_UUID = UUID.fromString("00001802-0000-1000-8000-00805f9b34fb");
private static final UUID ALERT_LEVEL_UUID = UUID.fromString("00002a06-0000-1000-8000-00805f9b34fb");
public void ClickButton(View view)
{
    BluetoothGattService alertService = mGatt.getService(IMMEDIATE_ALERT_UUID);
    if (alertService == null)
    {
        Toast.makeText(this, "Immediate Alert service not found!", 1)
                .show();
        return;
    }
    BluetoothGattCharacteristic alertLevel = alertService.getCharacteristic(ALERT_LEVEL_UUID);
    if (alertLevel == null)
    {
        Toast.makeText(this, "Alert Level charateristic not found!", 1)
                .show();
        return;
    }
    alertLevel.setValue(ALERT_HIGH, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
    mGatt.writeCharacteristic(alertLevel);
}

但没有任何 Action 发生!

我找到了这个应用 iTracing在 Play 商店上，它运行良好，可以让 ble 设备发出蜂鸣声。

我不知道我的代码哪里遗漏了；并且不知道我以前使用的功能或与此设备的连接初始化中的问题!

最后，这是我使用的完整代码

public class MainActivity extends Activity {
    private BluetoothAdapter mBluetoothAdapter;
    private int REQUEST_ENABLE_BT = 1;
    private Handler mHandler;
    private static final long SCAN_PERIOD = 1000*60;
    private BluetoothLeScanner mLEScanner;
    private ScanSettings settings;
    private List<ScanFilter> filters;
    private BluetoothGatt mGatt;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mHandler = new Handler();
    if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
        Toast.makeText(this, "BLE Not Supported",
                Toast.LENGTH_SHORT).show();
        finish();
    }
    final BluetoothManager bluetoothManager =
            (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
    mBluetoothAdapter = bluetoothManager.getAdapter();

}

@Override
protected void onResume() {
    super.onResume();
    if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    } else {
        if (Build.VERSION.SDK_INT >= 21) {
            mLEScanner = mBluetoothAdapter.getBluetoothLeScanner();
            settings = new ScanSettings.Builder()
                    .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
                    .build();
            filters = new ArrayList<ScanFilter>();
        }
        scanLeDevice(true);
    }
}

@Override
protected void onPause() {
    super.onPause();
    if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
        scanLeDevice(false);
    }
}

@Override
protected void onDestroy() {
    if (mGatt == null) {
        return;
    }
    mGatt.close();
    mGatt = null;
    super.onDestroy();
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_ENABLE_BT) {
        if (resultCode == Activity.RESULT_CANCELED) {
            //Bluetooth not enabled.
            finish();
            return;
        }
    }
    super.onActivityResult(requestCode, resultCode, data);
}

private void scanLeDevice(final boolean enable) {
    if (enable) {
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                if (Build.VERSION.SDK_INT < 21) {
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                } else {
                    mLEScanner.stopScan(mScanCallback);

                }
            }
        }, SCAN_PERIOD);
        if (Build.VERSION.SDK_INT < 21) {
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mLEScanner.startScan(filters, settings, mScanCallback);
        }
    } else {
        if (Build.VERSION.SDK_INT < 21) {
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        } else {
            mLEScanner.stopScan(mScanCallback);
        }
    }
}


private ScanCallback mScanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        Log.i("callbackType", String.valueOf(callbackType));
        Log.i("result", result.toString());
        BluetoothDevice btDevice = result.getDevice();
        String DeviceAddress = btDevice.getAddress().trim();            
        if(DeviceAddress.equals("FF:FF:00:01:05:07"))
            connectToDevice(btDevice);
    }

    @Override
    public void onBatchScanResults(List<ScanResult> results) {
        for (ScanResult sr : results) {
            Log.i("ScanResult - Results", sr.toString());
        }
    }

    @Override
    public void onScanFailed(int errorCode) {
        Log.e("Scan Failed", "Error Code: " + errorCode);
    }
};

private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {
            @Override
            public void onLeScan(final BluetoothDevice device, int rssi,
                                 byte[] scanRecord) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Log.i("onLeScan", device.toString());
                        connectToDevice(device);
                    }
                });
            }
        };

String address;
public void connectToDevice(BluetoothDevice device) {
    if (mGatt == null) {
        address = device.getAddress();
        mGatt = device.connectGatt(this, false, gattCallback);
    }
}

private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        Log.i("onConnectionStateChange", "Status: " + status);
        switch (newState) {
            case BluetoothProfile.STATE_CONNECTED:
                Log.i("gattCallback", "STATE_CONNECTED");
                mGatt.discoverServices();
                break;
            case BluetoothProfile.STATE_DISCONNECTED:
                Log.e("gattCallback", "STATE_DISCONNECTED");
                break;
            default:
                Log.e("gattCallback", "STATE_OTHER");
        }

    }

    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {
        List<BluetoothGattService> services = gatt.getServices();
        Log.i("onServicesDiscovered", services.toString());
        gatt.readCharacteristic(services.get(1).getCharacteristics().get
                (0));
    }

    @Override
    public void onCharacteristicRead(BluetoothGatt gatt,
                                     BluetoothGattCharacteristic
                                             characteristic, int status) {
        Log.i("onCharacteristicRead", characteristic.toString());
        gatt.disconnect();
    }
};

private static final int ALERT_HIGH = 2;
private static final UUID IMMEDIATE_ALERT_UUID = UUID.fromString("00001802-0000-1000-8000-00805f9b34fb");
private static final UUID ALERT_LEVEL_UUID = UUID.fromString("00002a06-0000-1000-8000-00805f9b34fb");
public void ClickButton(View view)
{
    BluetoothGattService alertService = mGatt.getService(IMMEDIATE_ALERT_UUID);
    if (alertService == null)
    {
        Toast.makeText(this, "Immediate Alert service not found!", 1)
                .show();
        return;
    }
    BluetoothGattCharacteristic alertLevel = alertService.getCharacteristic(ALERT_LEVEL_UUID);
    if (alertLevel == null)
    {
        Toast.makeText(this, "Alert Level charateristic not found!", 1)
                .show();
        return;
    }
    alertLevel.setValue(ALERT_HIGH, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
    mGatt.writeCharacteristic(alertLevel);
}
}

我将不胜感激。

Answer 1

这就是我在代码中的做法。

    byte[] valToWrite = parseHexStringToBytes("0x0" + alertLevel);
    immediateAlertChar.setValue(valToWrite);
    boolean val = gatt.writeCharacteristic(immediateAlertChar);

同时检查 onCharacteristicWrite() 方法中的响应