问题
I want to make a simple flashlite application using camera2 api. I am using the following code:
public class FlashLightUtilForL {
private CameraCaptureSession mSession;
private CaptureRequest.Builder mBuilder;
private CameraDevice mCameraDevice;
private CameraManager mCameraManager;
public FlashLightUtilForL(Context context) {
try {
mCameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
//here to judge if flash is available
CameraCharacteristics cameraCharacteristics = mCameraManager.getCameraCharacteristics("0");
boolean flashAvailable = cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
if (flashAvailable) {
mCameraManager.openCamera("0", new MyCameraDeviceStateCallback(), null);
} else {
//todo: throw Exception
}
//mCameraManager.openCamera("0", new MyCameraDeviceStateCallback(), null);
} catch (Exception e) {
e.printStackTrace();
}
}
class MyCameraDeviceStateCallback extends CameraDevice.StateCallback {
@Override
public void onOpened(CameraDevice camera) {
mCameraDevice = camera;
//get builder
try {
mBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_MANUAL);
//flash on, default is on
mBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AF_MODE_AUTO);
mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH);
List<Surface> list = new ArrayList<Surface>();
SurfaceTexture mSurfaceTexture = new SurfaceTexture(1);
Size size = getSmallestSize(mCameraDevice.getId());
mSurfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight());
Surface mSurface = new Surface(mSurfaceTexture);
list.add(mSurface);
mBuilder.addTarget(mSurface);
camera.createCaptureSession(list, new MyCameraCaptureSessionStateCallback(), null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onDisconnected(CameraDevice camera) {
}
@Override
public void onError(CameraDevice camera, int error) {
}
}
private Size getSmallestSize(String cameraId) throws CameraAccessException {
Size[] outputSizes = mCameraManager.getCameraCharacteristics(cameraId)
.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)
.getOutputSizes(SurfaceTexture.class);
if (outputSizes == null || outputSizes.length == 0) {
throw new IllegalStateException(
"Camera " + cameraId + "doesn't support any outputSize.");
}
Size chosen = outputSizes[0];
for (Size s : outputSizes) {
if (chosen.getWidth() >= s.getWidth() && chosen.getHeight() >= s.getHeight()) {
chosen = s;
}
}
return chosen;
}
/**
* session callback
*/
class MyCameraCaptureSessionStateCallback extends CameraCaptureSession.StateCallback {
@Override
public void onConfigured(CameraCaptureSession session) {
mSession = session;
try {
mSession.setRepeatingRequest(mBuilder.build(), null, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
}
}
public void turnOnFlashLight() {
try {
mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH);
mSession.setRepeatingRequest(mBuilder.build(), null, null);
} catch (Exception e) {
e.printStackTrace();
}
}
public void turnOffFlashLight() {
try {
mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_OFF);
mSession.setRepeatingRequest(mBuilder.build(), null, null);
} catch (Exception e) {
e.printStackTrace();
}
}
private void close() {
if (mCameraDevice == null || mSession == null) {
return;
}
mSession.close();
mCameraDevice.close();
mCameraDevice = null;
mSession = null;
}
}
And here is how I use this class from my main activity:
FlashLightUtilForL util = new FlashLightUtilForL(getApplicationContext());
util.turnOnFlashLight();
But it does nothing. I found that there is an error while opening camera, but there is no hint on what this erros is caused by. here is the log:
This is printed three times in a row:
11-10 15:27:32.881 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value manual
11-10 15:27:32.881 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value fullscan
11-10 15:27:32.881 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value nashville
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value hefe
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value valencia
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value xproll
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value lofi
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value sierra
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value walden
11-10 15:27:32.882 11801-11801/com.flashlight W/ArrayUtils: Ignoring invalid value normal
and then once:
11-10 15:27:32.909 11801-11801/com.flashlight I/CameraManager: Using legacy camera HAL.
11-10 15:27:32.911 11801-12695/com.flashlight W/Camera: An error occurred while connecting to camera: 0
I could not even find anything related to this particular error in camera2. What could cause the problem? The device is Redmi note 2 with 5.0.2, camera has flashlight, and I have added the camera permission in manifest.
回答1:
I suspect your issue is from CameraDevice.TEMPLATE_MANUAL. Not all devices support this. Also I do not think this works well when the device is using legacy support. Try switching to CameraDevice.TEMPLATE_PREVIEW.
Also, do not forget to release the SufaceTexture when you are don with it.
来源：https://stackoverflow.com/questions/40529057/android-camera2-api-opencamera-error