我的应用程序应包含全屏CameraPreview。我不知道自己的错误原因，该应用在启动后会迅速关闭。
这是我的代码：
主要活动
public class MainActivity extends AppCompatActivity{
private static final String LOG = "MainActivity.java";
private Camera mCamera;
private CameraPreview mPreview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FloatingActionButton fabPref = (FloatingActionButton) findViewById(R.id.fabPref);
fabPref.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
}
});
FloatingActionButton fabPhoto = (FloatingActionButton) findViewById(R.id.fabPhoto);
fabPhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
}
});
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
if(checkCameraHardware(this)==true){
Log.e("CAMERA", "vorhanden");
// Create an instance of Camera
mCamera = getCameraInstance();
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
preview.addView(mPreview);
}else{
Log.e("CAMERA", "nicht vorhanden");
}
}
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
return true;
} else {
return false;
}
}
public Camera getCameraInstance(){
Camera c = null;
try {
releaseCameraAndPreview();
c = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK); // attempt to get a Camera instance
Log.e(LOG, "CameraInstance: " + c + " RUNS");
}
catch (Exception e){
Log.e(LOG, "Camera not available");
Log.e(LOG, "CameraInstance: " + c);
}
Log.e(LOG, "CameraInstance: " + c);
return c; // returns null if camera is unavailable
}
private void releaseCameraAndPreview() {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
}
}
这是我的CameraPreview的代码：
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "CameraPreview.java";
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
这是运行应用程序后的LogCat：
2-16 19:54:06.621 13572-13572/de.aintlarry.shotanalysis I/art: Late-enabling -Xcheck:jni
12-16 19:54:06.622 13572-13572/de.aintlarry.shotanalysis I/art: VMHOOK: rlim_cur : 0 pid:13572
12-16 19:54:06.717 13572-13572/de.aintlarry.shotanalysis W/System: ClassLoader referenced unknown path: /data/app/de.aintlarry.shotanalysis-2/lib/arm64
12-16 19:54:06.834 13572-13572/de.aintlarry.shotanalysis E/CAMERA: vorhanden
12-16 19:54:06.847 13572-13572/de.aintlarry.shotanalysis W/CameraBase: An error occurred while connecting to camera: 0
12-16 19:54:07.149 13572-13572/de.aintlarry.shotanalysis W/CameraBase: An error occurred while connecting to camera: 0
12-16 19:54:07.450 13572-13572/de.aintlarry.shotanalysis W/CameraBase: An error occurred while connecting to camera: 0
12-16 19:54:07.751 13572-13572/de.aintlarry.shotanalysis W/CameraBase: An error occurred while connecting to camera: 0
12-16 19:54:08.052 13572-13572/de.aintlarry.shotanalysis W/CameraBase: An error occurred while connecting to camera: 0
12-16 19:54:08.352 13572-13572/de.aintlarry.shotanalysis I/Camera2Mode: fail
12-16 19:54:08.352 13572-13572/de.aintlarry.shotanalysis E/MainActivity.java: Camera not available
12-16 19:54:08.352 13572-13572/de.aintlarry.shotanalysis E/MainActivity.java: CameraInstance: null
12-16 19:54:08.352 13572-13572/de.aintlarry.shotanalysis E/MainActivity.java: CameraInstance: null
12-16 19:54:08.430 13572-13621/de.aintlarry.shotanalysis I/Adreno: QUALCOMM build : 8e7809e, Ic2ca81afa7
Build Date : 09/18/15
OpenGL ES Shader Compiler Version: XE031.05.13.02
Local Branch :
Remote Branch : refs/tags/AU_LINUX_ANDROID_PRIVATE_REDFOX64_MBR_RB1.05.01.01.003.020
Remote Branch : NONE
Reconstruct Branch : NOTHING
12-16 19:54:08.481 13572-13572/de.aintlarry.shotanalysis E/AndroidRuntime: FATAL EXCEPTION: main
Process: de.aintlarry.shotanalysis, PID: 13572
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.hardware.Camera.setPreviewDisplay(android.view.SurfaceHolder)' on a null object reference
at de.aintlarry.shotanalysis.CameraPreview.surfaceCreated(CameraPreview.java:33)
at android.view.SurfaceView.updateWindow(SurfaceView.java:582)
at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:177)
at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:944)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2140)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1162)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6229)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:873)
at android.view.Choreographer.doCallbacks(Choreographer.java:676)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:859)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:168)
at android.app.ActivityThread.main(ActivityThread.java:5781)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)
12-16 19:54:10.562 13572-13572/de.aintlarry.shotanalysis D/Process: killProcess, pid=13572
12-16 19:54:10.571 13572-13572/de.aintlarry.shotanalysis D/Process: com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException:113 java.lang.ThreadGroup.uncaughtException:693 java.lang.ThreadGroup.uncaughtException:69
有人知道这个问题吗？我尝试了所有发现的建议。
最佳答案
请改变这个
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) { //This catch block does not handle NullPointers
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
对此
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (Exception e) { //This catch block does handle NullPointers
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
您使用的
catch块太窄，无法捕获mCamera对象为null。这样可以防止崩溃，但是您还应该检查mCamera为什么在那里为null，以及是否可以/应该为null。但是，完全有可能它尚未完全初始化，将在以后的调用中:-)