在Android中，可以使用BluetoothAdapter和BluetoothGatt类来创建BLE接收器/发射器堆栈。下面是一个示例代码，展示了如何在跨多个活动中使用BLE接收器/发射器堆栈。

首先，在你的项目中创建一个名为"BLEManager"的类，用于管理BLE连接和通信。这个类应该是一个单例类，以确保在整个应用程序中只有一个实例。

public class BLEManager {
    private static BLEManager instance;
    private BluetoothAdapter bluetoothAdapter;
    private BluetoothGatt bluetoothGatt;

    private BLEManager() {
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    }

    public static BLEManager getInstance() {
        if (instance == null) {
            instance = new BLEManager();
        }
        return instance;
    }

    public boolean isBluetoothSupported() {
        return bluetoothAdapter != null;
    }

    public boolean isBluetoothEnabled() {
        return bluetoothAdapter.isEnabled();
    }

    public void enableBluetooth(Activity activity, int requestCode) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        activity.startActivityForResult(enableBtIntent, requestCode);
    }

    public void startScan(BluetoothAdapter.LeScanCallback callback) {
        bluetoothAdapter.startLeScan(callback);
    }

    public void stopScan(BluetoothAdapter.LeScanCallback callback) {
        bluetoothAdapter.stopLeScan(callback);
    }

    public void connectToDevice(BluetoothDevice device, BluetoothGattCallback callback) {
        bluetoothGatt = device.connectGatt(context, false, callback);
    }

    public void disconnectDevice() {
        if (bluetoothGatt != null) {
            bluetoothGatt.disconnect();
            bluetoothGatt.close();
            bluetoothGatt = null;
        }
    }

    // Other BLE operations like read, write, subscribe, etc.
}

然后，在需要使用BLE功能的活动中，你可以通过调用BLEManager.getInstance()来获取BLEManager的实例，并使用它来执行BLE操作。

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_ENABLE_BT = 1;
    private BLEManager bleManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bleManager = BLEManager.getInstance();

        if (!bleManager.isBluetoothSupported()) {
            // Bluetooth is not supported on this device
            return;
        }

        if (!bleManager.isBluetoothEnabled()) {
            // Bluetooth is not enabled, ask the user to enable it
            bleManager.enableBluetooth(this, REQUEST_ENABLE_BT);
        } else {
            // Bluetooth is enabled, start scanning for devices
            startScan();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_ENABLE_BT && resultCode == RESULT_OK) {
            // Bluetooth is enabled, start scanning for devices
            startScan();
        }
    }

    private void startScan() {
        bleManager.startScan(leScanCallback);
        // TODO: Update UI to show scanning progress
    }

    private void stopScan() {
        bleManager.stopScan(leScanCallback);
        // TODO: Update UI to show scanning complete
    }

    private BluetoothAdapter.LeScanCallback leScanCallback = new BluetoothAdapter.LeScanCallback() {
        @Override
        public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
            // TODO: Process scanned device, e.g., add it to a list
        }
    };

    @Override
    protected void onDestroy() {
        super.onDestroy();
        stopScan();
        bleManager.disconnectDevice();
    }
}

这是一个简单的示例，演示了如何使用一个单例的BLEManager类来管理BLE连接和通信，并在多个活动中使用它。你可以根据你的需求扩展这个示例，添加其他BLE操作，如读取、写入、订阅等。