我使用Camera2API构建相机活动，将拍摄的图像发送到另一个活动。在某些设备上它可以工作，但在其他设备（较慢的设备）上，我得到一个java.lang.IllegalStateException，它表示＆＃34;会话已经关闭;进一步的变化是非法的＆＃34; 。
我在这一行得到了这个例外（在updatePreview（）中）：
cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
这是我的完整代码：
public class NewCamera extends CustomActivity implements TimingActivity {
private static final String TAG = "NewCamera";
private ImageView takePictureButton;
private TextureView textureView;
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
static {
ORIENTATIONS.append(Surface.ROTATION_0, 90);
ORIENTATIONS.append(Surface.ROTATION_90, 0);
ORIENTATIONS.append(Surface.ROTATION_180, 270);
ORIENTATIONS.append(Surface.ROTATION_270, 180);
}
private String cameraId;
protected CameraDevice cameraDevice;
protected CameraCaptureSession cameraCaptureSessions;
protected CaptureRequest.Builder captureRequestBuilder;
private Semaphore mCameraOpenCloseLock = new Semaphore(1);
private Size imageDimension;
private ImageReader imageReader;
private static final int REQUEST_CAMERA_PERMISSION = 200;
private Handler mBackgroundHandler;
private HandlerThread mBackgroundThread;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_camera);
textureView = (TextureView) findViewById(R.id.textureView);
textureView.setSurfaceTextureListener(textureListener);
takePictureButton = (ImageView) findViewById(R.id.capture);
takePictureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
takePicture();
captureRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
finish();
}
});
changeFlashImage();
}
TextureView.SurfaceTextureListener textureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
//open your camera here
//transfromImage(width, height);
openCamera();
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
// Transform you image captured size according to the surface width and height
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
};
private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraOpenCloseLock.release();
cameraDevice = camera;
createCameraPreview();
}
@Override
public void onDisconnected(CameraDevice camera) {
mCameraOpenCloseLock.release();
camera.close();
cameraDevice = null;
}
@Override
public void onError(CameraDevice camera, int error) {
mCameraOpenCloseLock.release();
camera.close();
cameraDevice = null;
safeDestroy();
}
};
final CameraCaptureSession.CaptureCallback captureCallbackListener = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
createCameraPreview();
}
};
private void safeDestroy() {
Intent intent = getIntent();
finish();
startActivity(intent);
}
protected void startBackgroundThread() {
mBackgroundThread = new HandlerThread("Camera Background");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
protected void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
protected void takePicture() {
if(null == cameraDevice) {
Log.e(TAG, "cameraDevice is null");
return;
}
try {
ImageReader reader = ImageReader.newInstance(imageDimension.getWidth(), imageDimension.getHeight(), ImageFormat.JPEG, 1);
List<Surface> outputSurfaces = new ArrayList<Surface>(2);
outputSurfaces.add(reader.getSurface());
outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureRequestBuilder.addTarget(reader.getSurface());
captureRequestBuilder.set(CaptureRequest.JPEG_QUALITY, (byte) 100);
switch(Preferences.getInstance().flashMode % 2) {
case 0:
//off
captureRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
break;
case 1:
//on
captureRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_TORCH);
break;
}
// Orientation
int rotation = getWindowManager().getDefaultDisplay().getRotation();
captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
ByteBuffer buffer = reader.acquireLatestImage().getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.capacity()];
buffer.get(bytes);
//handle bytes - pass to another activity
}
};
reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
final CameraCaptureSession.CaptureCallback captureListener = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
}
};
cameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
session.capture(captureRequestBuilder.build(), captureListener, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
safeDestroy();
}
}, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
protected void createCameraPreview() {
try {
SurfaceTexture texture = textureView.getSurfaceTexture();
if(texture == null) {
return;
}
texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
Surface surface = new Surface(texture);
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
captureRequestBuilder.addTarget(surface);
captureRequestBuilder.set(CaptureRequest.JPEG_QUALITY, (byte) 100);
cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback(){
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
//The camera is already closed
if (null == cameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
cameraCaptureSessions = cameraCaptureSession;
updatePreview();
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void openCamera() {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED
|| ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(NewCamera.this, new String[]{Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CAMERA_PERMISSION);
return;
}
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
Log.e(TAG, "is camera open");
try {
cameraId = manager.getCameraIdList()[0];
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
assert map != null;
imageDimension = map.getOutputSizes(SurfaceTexture.class)[0];
transfromImage(textureView.getWidth(), textureView.getHeight());
manager.openCamera(cameraId, stateCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
Log.e(TAG, "openCamera X");
}
protected void updatePreview() {
if(null == cameraDevice) {
Log.e(TAG, "updatePreview error, return");
}
captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
try {
cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
protected void onRestart() {
super.onRestart();
changeFlashImage();
}
@Override
protected void onResume() {
super.onResume();
changeFlashImage();
startBackgroundThread();
if (textureView.isAvailable()) {
openCamera();
} else {
textureView.setSurfaceTextureListener(textureListener);
}
}
@Override
protected void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
private void closeCamera() {
try {
mCameraOpenCloseLock.acquire();
if (cameraCaptureSessions != null) {
cameraCaptureSessions.close();
cameraCaptureSessions = null;
}
if (cameraDevice != null) {
cameraDevice.close();
cameraDevice = null;
}
if (null != imageReader) {
imageReader.close();
imageReader = null;
}
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
mCameraOpenCloseLock.release();
}
}
@Override
protected void onDestroy() {
super.onDestroy();
if(cameraCaptureSessions!=null){
cameraCaptureSessions.close();
cameraCaptureSessions=null;
}
if (cameraDevice!=null){
cameraDevice.close();
cameraDevice=null;
if(imageReader!=null){
imageReader.close();
imageReader=null;
}
}
}
private void transfromImage (int width, int height) {
Matrix matrix = new Matrix();
int rotation = getWindowManager().getDefaultDisplay().getRotation();
RectF textureRectF = new RectF(0, 0, width, height);
RectF previewRectF = new RectF(0, 0, imageDimension.getHeight(), imageDimension.getWidth());
float centerX = textureRectF.centerX();
float centerY = textureRectF.centerY();
if ((rotation == Surface.ROTATION_90) || (rotation == Surface.ROTATION_270)) {
previewRectF.offset(centerX - previewRectF.centerX(), centerY - previewRectF.centerY());
matrix.setRectToRect(textureRectF, previewRectF, Matrix.ScaleToFit.FILL);
float scale = Math.max ((float) width / imageDimension.getWidth(), (float)height / imageDimension.getHeight());
matrix.postScale(scale, scale, centerX, centerY);
matrix.postRotate(90 * (rotation - 2), centerX, centerY);
}
textureView.setTransform(matrix);
}
public void changeFlashImage() {
ImageView ivFlash = (ImageView) findViewById(R.id.flash);
switch(Preferences.getInstance().flashMode % 2) {
case 0:
ivFlash.setImageResource(R.drawable.flash_off);
break;
case 1:
ivFlash.setImageResource(R.drawable.flash_on);
break;
}
}
public void changeFlash(View view) {
Preferences.getInstance().flashMode++;
changeFlashImage();
}
}
启动相机活动时出现此异常。当它发生时，textureView没有得到更新。我对Camera2API没有多少经验。非常感谢准备帮助的人们！
答案 0 :(得分：0)
检查所有摄像机配置是否都设置了标志，因为在后台并行设置配置时，您必须给mCaptureSession的repeatingRequest带来一些延迟。在我的情况下，我通过提供500 ms的延迟来设置repeatingRequest来解决此异常：
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
try {
mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(),
mCaptureCallback, null);
} catch (CameraAccessException e) {
Log.e(TAG, "Failed to start camera preview because it couldn't access camera", e);
} catch (IllegalStateException e) {
Log.e(TAG, "Failed to start camera preview.", e);
}
}
}, 500);
最好的快乐编码：-）