检测到脸部时采取措施（Android Camera2 API）

如果未检测到脸部，我需要隐藏相机拍摄按钮。我已经尝试了三天了。当检测到脸部时，我找不到采取行动的方法。

注意：此代码工作正常，我只需要在什么地方添加面部检测器？然后使用此面部检测器对相机拍摄按钮进行操作

btn_shot.setVisibility(view.GONE)

这是在创建相机预览：

private void creatCameraPreview() throws CameraAccessException {
        SurfaceTexture texture = textureView.getSurfaceTexture();
        texture.setDefaultBufferSize(imageDimensions.getWidth(),
imageDimensions.getHeight());

        Surface surface = new Surface(texture);

        captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        captureRequestBuilder.addTarget(surface);

        cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
            @Override
            public void onConfigured(@NonNull CameraCaptureSession session) {
                if (cameraDevice == null)
                    return;

                cameraCaptureSession = session;
                try {
                    updatePreview();
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                }

            }

            @Override
            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                Toast.makeText(CameraTaken.this, "Configuration Changed", Toast.LENGTH_SHORT).show();

            }
        }, null);
    }

这里打开相机：

private void openCamera() throws CameraAccessException {
        CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);

        assert manager != null;
        cameraId = manager.getCameraIdList()[0]; //[0] for the back facing camera [1] for the front facing camera

        CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);

        StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);


        assert map != null;
        imageDimensions = map.getOutputSizes(SurfaceTexture.class)[0];

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(this, Manifest.permission.INTERNET) != PackageManager.PERMISSION_GRANTED) {

            ActivityCompat.requestPermissions(CameraTaken.this, new String[]{
                    Manifest.permission.CAMERA,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE,
                    Manifest.permission.INTERNET}, 101);
            return;
        }
        manager.openCamera(cameraId, stateCallBack, null);




    }