我正在尝试制作自定义相机应用程序,但是每当我运行我的程序时,
得到-
不幸的是应用程序已停止
日志猫:
05-30 14:47:09.844: D/CameraCaptureActivity(797): getCameraInstance()Camera:: null
05-30 14:47:09.855: D/CameraCaptureActivity(797): getCameraInstance()open:: null
05-30 14:47:09.855: D/CameraCaptureActivity(797): mCamera:: null
05-30 14:47:09.895: D/CameraCaptureActivity(797): mCamera :: null
05-30 14:47:09.895: D/CameraCaptureActivity(797): mSurfaceHolder :: android.view.SurfaceView$4@40d06ef8
05-30 14:47:09.924: D/CameraCaptureActivity(797): mCameraPreview :: com.example.demo.CameraPreview{40d06860 V.E..... ......I. 0,0-0,0}
05-30 14:47:09.924: D/CameraCaptureActivity(797): FrameLayout :: android.widget.FrameLayout{40cfa7d8 V.E..... ......I. 0,0-0,0 #7f080000 app:id/camera_preview}
05-30 14:47:09.954: D/CameraCaptureActivity(797): captureButton :: android.widget.Button{40cfad50 VFED..C. ......I. 0,0-0,0 #7f080001 app:id/button_capture}
05-30 14:47:04.327: D/AndroidRuntime(797): Shutting down VM
05-30 14:47:04.327: W/dalvikvm(797): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
05-30 14:47:04.458: E/AndroidRuntime(797): FATAL EXCEPTION: main
05-30 14:47:04.458: E/AndroidRuntime(797): java.lang.NullPointerException
05-30 14:47:04.458: E/AndroidRuntime(797): at com.example.demo.CameraPreview.surfaceCreated(CameraPreview.java:33)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.updateWindow(SurfaceView.java:569)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.access$000(SurfaceView.java:86)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:174)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:680)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1842)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doFrame(Choreographer.java:532)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.handleCallback(Handler.java:725)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.dispatchMessage(Handler.java:92)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Looper.loop(Looper.java:137)
05-30 14:47:04.458: E/AndroidRuntime(797): at android.app.ActivityThread.main(ActivityThread.java:5041)
05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invokeNative(Native Method)
05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invoke(Method.java:511)
05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-30 14:47:04.458: E/AndroidRuntime(797): at dalvik.system.NativeStart.main(Native Method)
错误:
java.lang.NullPointerException
线:
mCamera.setPreviewDisplay(surfaceHolder);
CameraPreview.java:
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
public static final String LOG_TAG = "CameraPreview";
private SurfaceHolder mSurfaceHolder;
private Camera mCamera;
// Constructor that obtains context and camera
@SuppressWarnings("deprecation")
public CameraPreview(Context context, Camera camera) {
super(context);
this.mCamera = camera;
Log.d(CameraCaptureActivity.LOG_TAG, "mCamera :: " +mCamera);
this.mSurfaceHolder = this.getHolder();
this.mSurfaceHolder.addCallback(this);
this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
Log.d(CameraCaptureActivity.LOG_TAG, "mSurfaceHolder :: " +mSurfaceHolder);
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
try {
mCamera.setPreviewDisplay(surfaceHolder);
Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (setPreview) :: " +mCamera);
mCamera.startPreview();
Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (startPreview) :: " +mCamera);
} catch (IOException e) {
// left blank for now
}
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
mCamera.stopPreview();
Log.d(CameraCaptureActivity.LOG_TAG, "surfaceDestroyed (stopPreview) :: " +mCamera);
mCamera.release();
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int format,
int width, int height) {
// start preview with new settings
try {
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
} catch (Exception e) {
// intentionally left blank for a test
}
}
}
CameraCaptureActivity.java:
public static final String LOG_TAG = "CameraCaptureActivity";
private Camera mCamera;
private CameraPreview mCameraPreview;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mCamera = getCameraInstance();
Log.d(CameraCaptureActivity.LOG_TAG, "mCamera:: " + mCamera);
mCameraPreview = new CameraPreview(this, mCamera);
Log.d(CameraCaptureActivity.LOG_TAG, "mCameraPreview :: " + mCameraPreview);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mCameraPreview);
Log.d(CameraCaptureActivity.LOG_TAG, "FrameLayout :: " + preview);
Button captureButton = (Button) findViewById(R.id.button_capture);
Log.d(CameraCaptureActivity.LOG_TAG, "captureButton :: " + captureButton);
captureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
Log.d(CameraCaptureActivity.LOG_TAG, "mCamera.takePicture :: " + mCamera);
}
});
}
/**
* Helper method to access the camera returns null if it cannot get the
* camera or does not exist
*
* @return
*/
private Camera getCameraInstance() {
Camera camera = null;
Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()Camera:: " + camera);
try {
camera = Camera.open();
Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()open:: " + camera);
} catch (Exception e) {
// cannot get camera or does not exist
}
return camera;
}
PictureCallback mPicture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile();
if (pictureFile == null) {
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
}
}
};
private static File getOutputMediaFile() {
File mediaStorageDir = new File(
Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MyCameraApp");
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
File mediaFile;
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "IMG_" + timeStamp + ".jpg");
return mediaFile;
}
}