我需要有关此代码的帮助。它给了我这个错误
java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“void android.hardware.camera2.CaptureRequest$Builder.set(android.hardware.camera2.CaptureRequest$Key, java.lang.Object)”
我的代码是
private int mState = STATE_PREVIEW;
private static final int REQUEST_CAMERA_PERMISSION_RESULT = 0;
private static final int REQUEST_WRITE_EXTERNAL_STORAGE_PERMISSION_RESULT = 1;
private static final int STATE_PREVIEW = 0;
private static final int STATE_WAIT_LOCK = 1;
private int mCaptureState = STATE_PREVIEW;
private TextureView mTextureView;
private TextureView.SurfaceTextureListener mSurfaceTextureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
setupCamera(width, height);
connectCamera();
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
};
private CameraDevice mCameraDevice;
private CameraDevice.StateCallback mCameraDeviceStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
mCameraDevice = camera;
startPreview();
}
@Override
public void onDisconnected(CameraDevice camera) {
camera.close();
mCameraDevice = null;
}
@Override
public void onError(CameraDevice camera, int error) {
camera.close();
mCameraDevice = null;
}
};
private HandlerThread mBackgroundHandlerThread;
private Handler mBackgroundHandler;
private String mCameraId;
private Size mPreviewSize;
private Size mImageSize;
private ImageReader mImageReader;
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = new
ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
mBackgroundHandler.post(new ImageSaver(reader.acquireLatestImage()));
}
};
private class ImageSaver implements Runnable {
private final Image mImage;
public ImageSaver(Image image) {
mImage = image;
}
@Override
public void run() {
ByteBuffer byteBuffer = mImage.getPlanes()[0].getBuffer();
byte[] bytes = new byte[byteBuffer.remaining()];
byteBuffer.get(bytes);
FileOutputStream fileOutputStream = null;
try {
fileOutputStream = new FileOutputStream(mImageFileName);
fileOutputStream.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if(fileOutputStream != null) {
try {
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
private MediaRecorder mMediaRecorder;
private int mTotalRotation;
private CameraCaptureSession mPreviewCaptureSession;
private CameraCaptureSession.CaptureCallback mPreviewCaptureCallback = new
CameraCaptureSession.CaptureCallback() {
private void process(CaptureResult captureResult) {
switch (mCaptureState) {
case STATE_PREVIEW:
// Do nothing
break;
case STATE_WAIT_LOCK:
mCaptureState = STATE_PREVIEW;
Integer afState = captureResult.get(CaptureResult.CONTROL_AF_STATE);
if(afState == CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED ||
afState == CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED) {
Toast.makeText(getApplicationContext(), "AF Locked!", Toast.LENGTH_SHORT).show();
startStillCaptureRequest();
}
break;
}
}
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
process(result);
}
};
private CaptureRequest mPreviewCaptureRequest;
private CaptureRequest.Builder mPreviewCaptureRequestBuilder;
private CameraCaptureSession mCameraCaptureSession;
private CameraCaptureSession.CaptureCallback mSessionCaptureCallback
= new CameraCaptureSession.CaptureCallback() {
private void process(CaptureResult result) {
switch(mState) {
case STATE_PREVIEW:
// Do nothing
break;
case STATE_WAIT_LOCK:
Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
if(afState == CaptureRequest.CONTROL_AF_STATE_FOCUSED_LOCKED) {
/*
unLockFocus();
Toast.makeText(getApplicationContext(), "Focus Lock Successful", Toast.LENGTH_SHORT).show();
*/
captureStillImage();
}
break;
}
}
@Override
public void onCaptureStarted(CameraCaptureSession session, CaptureRequest request, long timestamp, long frameNumber) {
super.onCaptureStarted(session, request, timestamp, frameNumber);
}
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
process(result);
}
@Override
public void onCaptureFailed(CameraCaptureSession session, CaptureRequest request, CaptureFailure failure) {
super.onCaptureFailed(session, request, failure);
Toast.makeText(getApplicationContext(), "Focus Lock Unsuccessful", Toast.LENGTH_SHORT).show();
}
};
private CaptureRequest.Builder mCaptureRequestBuilder;
private File mImageFolder;
private String mImageFileName;
private static SparseIntArray ORIENTATIONS = new SparseIntArray();
static {
ORIENTATIONS.append(Surface.ROTATION_0, 0);
ORIENTATIONS.append(Surface.ROTATION_90, 90);
ORIENTATIONS.append(Surface.ROTATION_180, 180);
ORIENTATIONS.append(Surface.ROTATION_270, 270);
}
private static class CompareSizeByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
return Long.signum((long) lhs.getWidth() * lhs.getHeight() /
(long) rhs.getWidth() * rhs.getHeight());
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
createImageFolder();
mTextureView = (TextureView) findViewById(R.id.textureView);
final Button button = (Button) findViewById(R.id.camera_button);
if (button != null) {
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
takePicture();
}
});
}
}
@Override
protected void onResume() {
super.onResume();
startBackgroundThread();
if (mTextureView.isAvailable()) {
setupCamera(mTextureView.getWidth(), mTextureView.getHeight());
connectCamera();
} else {
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(requestCode == REQUEST_CAMERA_PERMISSION_RESULT) {
if(grantResults[0] != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(getApplicationContext(),
"Application will not run without camera services", Toast.LENGTH_SHORT).show();
}
if(grantResults[1] != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(getApplicationContext(),
"Application will not have audio on record", Toast.LENGTH_SHORT).show();
}
}
if(requestCode == REQUEST_WRITE_EXTERNAL_STORAGE_PERMISSION_RESULT) {
if(grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this,
"Permission successfully granted!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this,
"App needs to save image to run", Toast.LENGTH_SHORT).show();
}
}
}
@Override
protected void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
@Override
public void onWindowFocusChanged(boolean hasFocas) {
super.onWindowFocusChanged(hasFocas);
View decorView = getWindow().getDecorView();
if(hasFocas) {
decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE
| View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
| View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
| View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
| View.SYSTEM_UI_FLAG_FULLSCREEN
| View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
}
}
private void setupCamera(int width, int height) {
CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
for(String cameraId : cameraManager.getCameraIdList()){
CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraId);
if(cameraCharacteristics.get(CameraCharacteristics.LENS_FACING) ==
CameraCharacteristics.LENS_FACING_FRONT){
continue;
}
StreamConfigurationMap map = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
int deviceOrientation = getWindowManager().getDefaultDisplay().getRotation();
mTotalRotation = sensorToDeviceRotation(cameraCharacteristics, deviceOrientation);
boolean swapRotation = mTotalRotation == 90 || mTotalRotation == 270;
int rotatedWidth = width;
int rotatedHeight = height;
if(swapRotation) {
rotatedWidth = height;
rotatedHeight = width;
}
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class), rotatedWidth, rotatedHeight);
mImageSize = chooseOptimalSize(map.getOutputSizes(ImageFormat.JPEG), rotatedWidth, rotatedHeight);
mImageReader = ImageReader.newInstance(mImageSize.getWidth(), mImageSize.getHeight(), ImageFormat.JPEG, 1);
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mBackgroundHandler);
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void connectCamera() {
CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if(ContextCompat.checkSelfPermission(this, android.Manifest.permission.CAMERA) ==
PackageManager.PERMISSION_GRANTED) {
cameraManager.openCamera(mCameraId, mCameraDeviceStateCallback, mBackgroundHandler);
} else {
if(shouldShowRequestPermissionRationale(android.Manifest.permission.CAMERA)) {
Toast.makeText(this,
"Video app required access to camera", Toast.LENGTH_SHORT).show();
}
requestPermissions(new String[] {android.Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO
}, REQUEST_CAMERA_PERMISSION_RESULT);
}
} else {
cameraManager.openCamera(mCameraId, mCameraDeviceStateCallback, mBackgroundHandler);
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void startPreview() {
SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface previewSurface = new Surface(surfaceTexture);
try {
mCaptureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mCaptureRequestBuilder.addTarget(previewSurface);
mCameraDevice.createCaptureSession(Arrays.asList(previewSurface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
mPreviewCaptureSession = session;
try {
mPreviewCaptureSession.setRepeatingRequest(mCaptureRequestBuilder.build(),
null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
Toast.makeText(getApplicationContext(),
"Unable to setup camera preview", Toast.LENGTH_SHORT).show();
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void startStillCaptureRequest() {
mCaptureRequestBuilder.addTarget(mImageReader.getSurface());
mCaptureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, mTotalRotation);
CameraCaptureSession.CaptureCallback stillCaptureCallback = new
CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureStarted(CameraCaptureSession session, CaptureRequest request, long timestamp, long frameNumber) {
super.onCaptureStarted(session, request, timestamp, frameNumber);
try {
createImageFileName();
} catch (IOException e) {
e.printStackTrace();
}
}
};
}
private void closeCamera() {
if(mCameraDevice != null) {
mCameraDevice.close();
mCameraDevice = null;
}
if(mMediaRecorder != null) {
mMediaRecorder.release();
mMediaRecorder = null;
}
}
private void startBackgroundThread() {
mBackgroundHandlerThread = new HandlerThread("CameraImage");
mBackgroundHandlerThread.start();
mBackgroundHandler = new Handler(mBackgroundHandlerThread.getLooper());
}
private void stopBackgroundThread() {
mBackgroundHandlerThread.quitSafely();
try {
mBackgroundHandlerThread.join();
mBackgroundHandlerThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private static int sensorToDeviceRotation(CameraCharacteristics cameraCharacteristics, int deviceOrientation) {
int sensorOrienatation = cameraCharacteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
deviceOrientation = ORIENTATIONS.get(deviceOrientation);
return (sensorOrienatation + deviceOrientation + 360) % 360;
}
private static Size chooseOptimalSize(Size[] choices, int width, int height) {
List<Size> bigEnough = new ArrayList<Size>();
for(Size option : choices) {
if(option.getHeight() == option.getWidth() * height / width &&
option.getWidth() >= width && option.getHeight() >= height) {
bigEnough.add(option);
}
}
if(bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizeByArea());
} else {
return choices[0];
}
}
private void createImageFolder() {
File imageFile = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
mImageFolder = new File(imageFile, "camera2VideoImage");
if(!mImageFolder.exists()) {
mImageFolder.mkdirs();
}
}
private File createImageFileName() throws IOException {
String timestamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String prepend = "IMAGE_" + timestamp + "_";
File imageFile = File.createTempFile(prepend, ".jpg", mImageFolder);
mImageFileName = imageFile.getAbsolutePath();
return imageFile;
}
private void captureStillImage() {
try {
CaptureRequest.Builder captureStillBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureStillBuilder.addTarget(mImageReader.getSurface());
int rotation = getWindowManager().getDefaultDisplay().getRotation();
captureStillBuilder.set(CaptureRequest.JPEG_ORIENTATION,
ORIENTATIONS.get(rotation));
CameraCaptureSession.CaptureCallback captureCallback =
new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
Toast.makeText(getApplicationContext(),
"Image Captured!", Toast.LENGTH_SHORT).show();
unLockFocus();
}
};
mCameraCaptureSession.capture(
captureStillBuilder.build(), captureCallback, null
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void takePicture() {
lockFocus();
}
private void lockFocus() {
try {
mPreviewCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CaptureRequest.CONTROL_AF_TRIGGER_START);
mState = STATE_WAIT_LOCK;
mCameraCaptureSession.capture(mPreviewCaptureRequestBuilder.build(),
mSessionCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void unLockFocus() {
try {
mState = STATE_PREVIEW;
mPreviewCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CaptureRequest.CONTROL_AF_TRIGGER_CANCEL);
mCameraCaptureSession.capture(mPreviewCaptureRequestBuilder.build(),
mSessionCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
堆栈跟踪：
05-29 13:23:15.601 511-511/com.example.pc.snadfinal E/AndroidRuntime: FATAL >EXCEPTION: main Process: >com.example.pc.snadfinal, PID: 511 Theme: >themes:{}
java.lang.NullPointerException：尝试在 com. example.pc.snadfinal.CameraActivity.lockFocus(CameraActivity.java:548) at com.example.pc.snadfinal.CameraActivity.takePicture(CameraActivity.java:541) at com.example.pc.snadfinal.CameraActivity.access$1100(CameraActivity .java:48) 在 com.example.pc.snadfinal.CameraActivity$6.onClick(CameraActivity.java:259) 在 android.view.View.performClick(View.java:5204) 在 android.view.View$PerformClick.run(View.java:21158) 在 android.os.Handler.handleCallback(Handler.java:739) 在android.os.Handler.dispatchMessage(Handler.java:95) 在 android.os.Looper.loop(Looper.java:148) 在 android.app.ActivityThread.main(ActivityThread.java:5461) 在 java.lang.reflect.Method.invoke(Native Method) 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 在 com.android.internal.os.ZygoteInit.main( ZygoteInit.java:616)
我认为该错误是由方法中的某些原因引起的，lockFocus()或者takePicture()我不知道是由什么引起的。
我将此添加到 lockFocus() 和 unlockFocus() mPreviewCaptureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
现在它给了我这个堆栈跟踪：
java.lang.NullPointerException：尝试在在 com.example.pc.snadfinal.CameraActivity.takePicture(CameraActivity.java:538) 在 com.example.pc.snadfinal 的 com.example.pc.snadfinal.CameraActivity.lockFocus(CameraActivity.java:548) 的空对象引用。 CameraActivity.access$1000(CameraActivity.java:48) 在 com.example.pc。snadfinal.CameraActivity$6.onClick(CameraActivity.java:256) at android.view.View.performClick(View.java:5204) at android.view.View$PerformClick.run(View.java:21158) at android.os。 Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread .java：5461) 在 java.lang.reflect.Method.invoke(Native Method) 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 在 com.android.internal.os.ZygoteInit.main( ZygoteInit.java:616)主要（ZygoteInit.java:616）主要（ZygoteInit.java:616）