Android的整个BLE栈源代码位于Android Open Source Project（AOSP）的代码库中。具体来说，BLE栈源代码可以在以下路径下找到：

/platform/packages/apps/Bluetooth/src/com/android/bluetooth/ble/

在此路径下，可以找到包含BLE客户端和服务端源代码的Java文件。BLE协议栈的C/C++实现位于以下路径：

/platform/external/bluetooth/bluedroid/

在这个目录中，可以找到对BLE协议栈各个组件的实现，包括广播、扫描、连接和数据传输等。下面是一个简单的例子，演示如何使用Android BLE栈来扫描并连接到BLE外设：

private BluetoothLeScanner leScanner;

private BluetoothGatt bluetoothGatt;

private ScanCallback scanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        BluetoothDevice device = result.getDevice();
        if (device.getName() != null && device.getName().equals("My Device")) {
            connectToDevice(device);
        }
    }
};

public void startScanning() {
    BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(BLUETOOTH_SERVICE);
    BluetoothAdapter adapter = bluetoothManager.getAdapter();
    leScanner = adapter.getBluetoothLeScanner();
    ScanFilter scanFilter = new ScanFilter.Builder().setDeviceName("My Device").build();
    ArrayList filters = new ArrayList<>();
    filters.add(scanFilter);
    ScanSettings scanSettings = new ScanSettings.Builder().build();
    leScanner.startScan(filters, scanSettings, scanCallback);
}

public void connectToDevice(BluetoothDevice device) {
    bluetoothGatt = device.connectGatt(this, false, gattCallback);
}

private BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        if (newState == BluetoothProfile.STATE_CONNECTED) {
            gatt.discoverServices();
        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            bluetoothGatt.close();
            bluetoothGatt = null;
        }
    }

    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {
        List services = gatt.getServices();
        // process discovered services and characteristics
    }
};