问题
I just switched my code from asynctask to rxjava2 and I'm randomly getting this exception on my nexus:
Camera is being used after Camera.release() was called in Galaxy s6 Edge
Following is my code-
Class Camera:
public class Cameras {
private static final String TAG = Cameras.class.getSimpleName();
private static final String SP_CAMERA_ID = "camera_id";
private static final int NO_NEXT_TASK = 0;
private static final int NEXT_TASK_RELEASE_COMPLETE = 1;
private static final int NEXT_TASK_SWITCH_COMPLETE = 2;
private static final int NEXT_TASK_START_PREVIEW = 3;
private Camera camera;
private int currentCameraId = -1;
private Camera.PreviewCallback previewCallback;
private byte[] buffer1, buffer2, buffer3;
private SurfaceTexture surfaceTexture;
private Listener listener;
public interface Listener {
void onCameraOpened(Camera.Size size, int angle);
}
private boolean cameraReleased = false;
public Cameras(Camera.PreviewCallback previewCallback, Listener listener) {
this.listener = listener;
this.previewCallback = previewCallback;
this.currentCameraId = Spin.INSTANCE.getSp().getInt(SP_CAMERA_ID, -1);
getCameraList();
}
private void getCameraList() {
int numberOfCameras = Camera.getNumberOfCameras();
Camera.CameraInfo camInfo = new Camera.CameraInfo();
for (int i = 0; i < numberOfCameras; i++) {
Camera.getCameraInfo(i, camInfo);
cams.add(camInfo.facing);
}
if (Camera.CameraInfo.CAMERA_FACING_BACK != currentCameraId
&& Camera.CameraInfo.CAMERA_FACING_FRONT != currentCameraId) {
currentCameraId = cams.get(cams.size() == 2 ? 1 : 0);
}
}
public boolean isSwitchCamAvailable() {
return Camera.getNumberOfCameras() > 1;
}
public void open(SurfaceTexture surfaceTexture) {
this.surfaceTexture = surfaceTexture;
init(NEXT_TASK_START_PREVIEW);
}
private void init(final int nextTask) {
if (cams.isEmpty()) {
Toast.makeText(Spin.getContext(), "Device have no camera", Toast.LENGTH_SHORT).show();
return;
}
cameraReleased = false;
if (Looper.getMainLooper().getThread() == Thread.currentThread()) {
Observable.defer(new Callable<ObservableSource<?>>() {
@Override
public ObservableSource<?> call() throws Exception {
synchronized (this) {
try {
camera = Camera.open(currentCameraId);
} catch (RuntimeException e) {
e.printStackTrace();
}
}
return Completable.complete().toObservable();
}
}).doOnComplete(() -> {
initComplete(nextTask);
Log.d("Complete", "Complete");
})
.subscribeOn(Schedulers.computation())
.observeOn(AndroidSchedulers.mainThread()).subscribe();
} else {
try {
synchronized (this) {
this.camera = Camera.open(currentCameraId);
}
initComplete(nextTask);
} catch (RuntimeException ignored) {
}
}
}
private void initComplete(int nextTask) {
if (camera == null) {
return;
}
//noinspection SynchronizeOnNonFinalField
synchronized (camera) {
try {
Camera.Parameters params = camera.getParameters();
Camera.Size size = getClosestFrameSize(params, 640);
params.setPreviewSize(size.width, size.height);
camera.setParameters(params);
camera.setPreviewCallbackWithBuffer(previewCallback);
int bufferSize = size.width * size.height
* ImageFormat.getBitsPerPixel(ImageFormat.NV21) / 8;
buffer1 = new byte[bufferSize];
buffer2 = new byte[bufferSize];
buffer3 = new byte[bufferSize];
camera.addCallbackBuffer(buffer1);
camera.addCallbackBuffer(buffer2);
camera.addCallbackBuffer(buffer3);
camera.setPreviewTexture(surfaceTexture);
int angle = rotateStream();
camera.setDisplayOrientation(angle);
if (currentCameraId == Camera.CameraInfo.CAMERA_FACING_FRONT && angle > 0)
angle = 360 - angle;
listener.onCameraOpened(size, angle);
routNextTask(nextTask);
} catch (IOException | RuntimeException e) {
e.printStackTrace();
}
}
}
private Camera.Size getClosestFrameSize(Camera.Parameters params, int width) {
Camera.Size result = null;
List<Camera.Size> sizes = params.getSupportedPreviewSizes();
Camera.Size currentSize = null;
int closestDistance = 0;
int currentDistance = 0;
for (int i = 0; i < sizes.size(); ++i) {
if (null == result) {
result = sizes.get(i);
closestDistance = Math.abs(result.width - width);
continue;
}
currentSize = sizes.get(i);
currentDistance = Math.abs(currentSize.width - width);
if (currentDistance < closestDistance) {
closestDistance = currentDistance;
result = currentSize;
if (closestDistance == 0) break;
}
}
return result;
}
public void stopPreview() {
stopPreview(NO_NEXT_TASK);
}
private String nextTaskStr(final int nextTask) {
String nextTaskStr = null;
switch (nextTask) {
case NO_NEXT_TASK:
nextTaskStr = "NO_NEXT_TASK";
break;
case NEXT_TASK_RELEASE_COMPLETE:
nextTaskStr = "NEXT_TASK_RELEASE_COMPLETE";
break;
case NEXT_TASK_SWITCH_COMPLETE:
nextTaskStr = "NEXT_TASK_SWITCH_COMPLETE";
break;
case NEXT_TASK_START_PREVIEW:
nextTaskStr = "NEXT_TASK_START_PREVIEW";
break;
}
return nextTaskStr;
}
private void stopPreview(final int nextTask) {
if (null == camera) return;
if (Looper.getMainLooper().getThread() == Thread.currentThread()) {
Observable.defer(new Callable<ObservableSource<?>>() {
@Override
public ObservableSource<?> call() throws Exception {
synchronized (this) {
if ( (null != camera) && (!cameraReleased) ) {
if (LogDog.isEnabled) ;
camera.stopPreview();
}
}
return Completable.complete().toObservable();
}
}).doOnComplete(() -> {
routNextTask(nextTask);
Log.d("Complete", "Complete");
})
.subscribeOn(Schedulers.computation())
.observeOn(AndroidSchedulers.mainThread()).subscribe();
} else {
synchronized (this) {
if ( (null != camera) && (!cameraReleased) ) {
camera.stopPreview();
}
}
routNextTask(nextTask);
}
}
private void routNextTask(int nextTask) {
if (NO_NEXT_TASK == nextTask) return;
if (NEXT_TASK_SWITCH_COMPLETE == nextTask) {
switchCamComplete();
} else if (NEXT_TASK_RELEASE_COMPLETE == nextTask) {
releaseComplete();
} else if (NEXT_TASK_START_PREVIEW == nextTask) {
startPreview(null);
}
}
public void startPreview(Camera.PreviewCallback cpc) {
if (null == camera) return;
synchronized (this) {
camera.startPreview();
switchCamOnAir = false;
}
}
private void releaseCamera() {
synchronized (this) {
if (null == camera) return;
camera.setPreviewCallback(null);
camera.release();
camera = null;
cameraReleased = true;
}
}
public void release() {
synchronized (this) {
if (null == camera) return;
stopPreview(NEXT_TASK_RELEASE_COMPLETE);
}
}
private void releaseComplete() {
synchronized (this) {
if (camera != null) {
camera.release();
cameraReleased = true;
camera = null;
}
}
buffer1 = null;
buffer2 = null;
buffer3 = null;
}
private boolean switchCamOnAir = false;
public void switchCam() {
if (!isSwitchCamAvailable()) return;
if (null == camera) return;
if (switchCamOnAir) return;
this.switchCamOnAir = true;
stopPreview(NEXT_TASK_SWITCH_COMPLETE);
}
private void switchCamComplete() {
releaseCamera();
if (currentCameraId == Camera.CameraInfo.CAMERA_FACING_FRONT) {
currentCameraId = Camera.CameraInfo.CAMERA_FACING_BACK;
} else {
currentCameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;
}
Spin.INSTANCE.getSp().edit().putInt(SP_CAMERA_ID, currentCameraId).apply();
init(NEXT_TASK_START_PREVIEW);
}
public int rotateStream() {
Camera.CameraInfo info = new Camera.CameraInfo();
Camera.getCameraInfo(currentCameraId, info);
WindowManager wm = (WindowManager) Spin.getContext()
.getSystemService(Context.WINDOW_SERVICE);
int rotation = wm.getDefaultDisplay().getRotation();
int degrees = 0;
switch (rotation) {
case Surface.ROTATION_0:
degrees = 0;
break;
case Surface.ROTATION_90:
degrees = 90;
break;
case Surface.ROTATION_180:
degrees = 180;
break;
case Surface.ROTATION_270:
degrees = 270;
break;
}
int result;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
result = (info.orientation + degrees) % 360;
result = (360 - result) % 360; // compensate the mirror
} else { // back-facing
result = (info.orientation - degrees + 360) % 360;
}
return result;
}
@SuppressWarnings("unused")
public int getDeviceDefaultOrientation() {
WindowManager windowManager = (WindowManager) Spin.getContext()
.getSystemService(Context.WINDOW_SERVICE);
Configuration config = Spin.getContext().getResources().getConfiguration();
int rotation = windowManager.getDefaultDisplay().getRotation();
if (((rotation == Surface.ROTATION_0 || rotation == Surface.ROTATION_180) &&
config.orientation == Configuration.ORIENTATION_LANDSCAPE)
|| ((rotation == Surface.ROTATION_90 || rotation == Surface.ROTATION_270) &&
config.orientation == Configuration.ORIENTATION_PORTRAIT)) {
return Configuration.ORIENTATION_LANDSCAPE;
} else {
return Configuration.ORIENTATION_PORTRAIT;
}
}
}
cameras.java:
if (Looper.getMainLooper().getThread() == Thread.currentThread()) {
Observable.defer(new Callable<ObservableSource<?>>() {
@Override
public ObservableSource<?> call() throws Exception {
if (LogDog.isEnabled) LogDog.e("Debug::"+TAG + "::stopPreview()::AsyncTask::doInBackground()", " (camera != null) =" + (camera != null) );
synchronized (this) {
if ( (null != camera) && (!cameraReleased) ) {
if (LogDog.isEnabled) LogDog.e("Debug::" + TAG + "::stopPreview()::AsyncTask::doInBackground()", " XXX CALL camera.stopPreview()");
camera.stopPreview();
}
}
return Completable.complete().toObservable();
}
}).doOnComplete(() -> {
routNextTask(nextTask);
Log.d("Complete", "Complete");
})
.subscribeOn(Schedulers.computation())
.observeOn(AndroidSchedulers.mainThread()).subscribe();
Not sure what I am doing wrong. Any ideas where I can release the camera or allocate it, so it works without any issues? Exception is as follows:
FATAL EXCEPTION: main io.reactivex.exceptions.OnErrorNotImplementedException: Camera is being used after Camera.release() was called at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:704) at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:701) at io.reactivex.internal.observers.LambdaObserver.onError(LambdaObserver.java:74) at io.reactivex.internal.operators.observable.ObservableObserveOn$ObserveOnObserver.checkTerminated(ObservableObserveOn.java:276) at io.reactivex.internal.operators.observable.ObservableObserveOn$ObserveOnObserver.drainNormal(ObservableObserveOn.java:172) at io.reactivex.internal.operators.observable.ObservableObserveOn$ObserveOnObserver.run(ObservableObserveOn.java:252) at io.reactivex.android.schedulers.HandlerScheduler$ScheduledRunnable.run(HandlerScheduler.java:109) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6119) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) Caused by: java.lang.RuntimeException: Camera is being used after Camera.release() was called at android.hardware.Camera._stopPreview(Native Method) at android.hardware.Camera.stopPreview(Camera.java:730) at com.media.video.Cameras$2.call(Cameras.java:413) at com.media.video.Cameras$2.call(Cameras.java:406) at io.reactivex.internal.operators.observable.ObservableDefer.subscribeActual(ObservableDefer.java:32) at io.reactivex.Observable.subscribe(Observable.java:10842) at io.reactivex.internal.operators.observable.ObservableDoOnEach.subscribeActual(ObservableDoOnEach.java:42) at io.reactivex.Observable.subscribe(Observable.java:10842) at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96) at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:38) at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:26) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:272) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) at java.lang.Thread.run(Thread.java:761)
回答1:
The code you wrote for releasing the camera is prone to have race-conditions. A small change which could already make a difference is setting the flag before the action happens.
cameraReleased = true;
camera.release();
camera = null;
It might be necessary to recheck the flag just before the release of the Camera, but for this you synchronized the code before. In this context the issue is, that you're calling synchronized(this) within the deferred Observable. Instead you should synchronize on the same instance like everywhere else, because this doesn't refer to the outer class. Instead use this@Cameras
@Override
public ObservableSource<?> call() throws Exception {
if (LogDog.isEnabled) LogDog.e("Debug::"+TAG + "::stopPreview()::AsyncTask::doInBackground()", " (camera != null) =" + (camera != null) );
synchronized (this@Cameras) {
if ( (null != camera) && (!cameraReleased) ) {
if (LogDog.isEnabled) LogDog.e("Debug::" + TAG + "::stopPreview()::AsyncTask::doInBackground()", " XXX CALL camera.stopPreview()");
camera.stopPreview();
}
}
return Completable.complete().toObservable();
}
Additional to this, you're use-case for Observable.defer() doesn't look right. The Completable.fromAction() factory might be more suitable.
来源：https://stackoverflow.com/questions/47796584/rxjava-2-exception-with-camera