视频录制应用不会被正确销毁。当我按“返回”按钮时，“相机应用程序”处于“暂停”（）。在启动APP的新实例时，视频录制失败。如果我手动杀死以前的实例并重新运行APP它的工作完美。根据我的假设，实现杀死和释放相机的所有生命周期。但集成或调用可能会产生问题。请帮忙解决一下。
CameraPreview类
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
private MyDrawing md;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
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) {
try {
// create the surface and start camera preview
if (mCamera == null) {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
}
} catch (IOException e) {
Log.d(VIEW_LOG_TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void refreshCamera(Camera camera) {
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
setCamera(camera);
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
//startFaceDetection();
} catch (Exception e) {
Log.d(VIEW_LOG_TAG, "Error starting camera preview: " + e.getMessage());
}
}
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.
refreshCamera(mCamera);
}
public void setCamera(Camera camera) {
//method to set a camera instance
mCamera = camera;
mCamera.setFaceDetectionListener(faceDetectionListener);
startFaceDetection();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
mCamera.release();
}
private Camera.FaceDetectionListener faceDetectionListener = new Camera.FaceDetectionListener() {
@Override
public void onFaceDetection(Camera.Face[] faces, Camera c) {
if (faces.length > 0) {
Log.d("FaceDetection", "face detected X and Y are as: " + faces.length +
" Face 1 Location X: " + faces[0].rect.centerX() +
"Y: " + faces[0].rect.centerY() +" LIES IN "+(MyDrawing.w-MyDrawing.radius) +"--"+(MyDrawing.w+MyDrawing.radius));
if(faces[0].rect.centerX()>=0 && faces[0].rect.centerX()<115 )
{
Log.d("ALERT = ", "Detection Started" );
AndroidVideoCaptureExample.capture.setText("Recording/ stopNsave ");
AndroidVideoCaptureExample.faceDetect();
}
} else {
Log.d("FaceDetection", "circle cordinates are as: " + (MyDrawing.w-MyDrawing.radius) +"cX"+ MyDrawing.radius+"cY");
}
}
};
public void startFaceDetection(){
// Try starting Face Detection
Camera.Parameters params = mCamera.getParameters();
// start face detection only *after* preview has started
if (params.getMaxNumDetectedFaces() > 0){
// camera supports face detection, so can start it:
mCamera.startFaceDetection();
}
}
}
主要
public class AndroidVideoCaptureExample extends Activity {
private static Camera mCamera;
private static int vWidth,vHeight;
private CameraPreview mPreview;
public static MediaRecorder mediaRecorder;
public static Button capture, switchCamera;
private Context myContext;
private FrameLayout cameraPreview;
private boolean cameraFront = false;
private static int desiredwidth=640, desiredheight=360;
private MyDrawing md;
public static boolean vRecording = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
myContext = this;
initialize();
Log.d("FaceDetection", "face detected BASEER" );
}
private int findFrontFacingCamera() {
int cameraId = -1;
// Search for the front facing camera
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
cameraId = i;
cameraFront = true;
break;
}
}
return cameraId;
}
public void onResume() {
super.onResume();
if (!hasCamera(myContext)) {
Toast toast = Toast.makeText(myContext, "Sorry, your phone does not have a camera!", Toast.LENGTH_LONG);
toast.show();
finish();
}
if (mCamera == null) {
// if the front facing camera does not exist
if (findFrontFacingCamera() < 0) {
Toast.makeText(this, "No front facing camera found.", Toast.LENGTH_LONG).show();
switchCamera.setVisibility(View.GONE);
}
mCamera = Camera.open(findFrontFacingCamera());
mCamera.setDisplayOrientation(90);
mPreview.refreshCamera(mCamera);
}
}
public void initialize() {
cameraPreview = (FrameLayout) findViewById(R.id.camera_preview);
mPreview = new CameraPreview(myContext, mCamera);
cameraPreview.addView(mPreview);
capture = (Button) findViewById(R.id.button_capture);
capture.setOnClickListener(captrureListener);
}
@Override
protected void onPause() {
super.onPause();
// when on Pause, release camera in order to be used from other
// applications
releaseCamera();
}
private boolean hasCamera(Context context) {
// check if the device has camera
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
return true;
} else {
return false;
}
}
static boolean recording = false;
OnClickListener captrureListener = new OnClickListener() {
@Override
public void onClick(View v) {
if (recording) {
// stop recording and release camera
mediaRecorder.stop(); // stop the recording
releaseMediaRecorder(); // release the MediaRecorder object
Toast.makeText(AndroidVideoCaptureExample.this, "Video captured!", Toast.LENGTH_LONG).show();
Toast.makeText(AndroidVideoCaptureExample.this, vWidth+"BY"+vHeight, Toast.LENGTH_LONG).show();
recording = false;
}
}
};
public static void faceDetect()
{
prepareMediaRecorder();
recording = true;
mediaRecorder.start();
}
private static void releaseMediaRecorder() {
if (mediaRecorder != null) {
mediaRecorder.reset(); // clear recorder configuration
mediaRecorder.release(); // release the recorder object
mediaRecorder = null;
mCamera.lock(); // lock camera for later use
}
}
private static boolean prepareMediaRecorder() {
List<Camera.Size> videosizes = mCamera.getParameters().getSupportedVideoSizes();
Camera.Size videosize = videosizes.get(1);
Camera.Size optimalVideoSize = getOptimalPreviewSize(videosize, desiredwidth, desiredheight);
vWidth = optimalVideoSize.width;//mCamera.getParameters().getPreviewSize().width;
vHeight = optimalVideoSize.height;//mCamera.getParameters().getPreviewSize().height;
mediaRecorder = new MediaRecorder();
mCamera.unlock();
mediaRecorder.setCamera(mCamera);
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
mediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_LOW));
mediaRecorder.setVideoEncodingBitRate(512* 1000);
mediaRecorder.setVideoFrameRate(15);
mediaRecorder.setVideoSize(optimalVideoSize.width, optimalVideoSize.height);
mediaRecorder.setOutputFile("/sdcard/myvideo.mp4");
mediaRecorder.setMaxDuration(600000); // Set max duration 60 sec.
mediaRecorder.setMaxFileSize(50000000); // Set max file size 50M
try {
mediaRecorder.prepare();
} catch (IllegalStateException e) {
releaseMediaRecorder();
return false;
} catch (IOException e) {
releaseMediaRecorder();
return false;
}
return true;
}
private void releaseCamera() {
// stop and release camera
if (mCamera != null) {
mCamera.release();
mCamera = null;
}
}
private static Camera.Size getOptimalPreviewSize(Camera.Size sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.2;
double targetRatio = (double) w / h;
if (sizes == null)
return null;
Camera.Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
// Try to find an size match aspect ratio and size
Camera.Size size = sizes;
Log.d("Camera", "Checking size " + size.width + "w " + size.height
+ "h");
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) <= ASPECT_TOLERANCE)
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
// Cannot find the one match the aspect ratio, ignore the
// requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
return optimalSize;
}
}
错误日志
错误/崩溃：如果应用程序进入前台并重新打开，一旦检测到面部（此检测开始录制视频）应用程序崩溃并出现以下错误。
E/MediaRecorder: start failed: -38
D/AndroidRuntime: Shutting down VM
W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x42230c08)
E/AndroidRuntime: FATAL EXCEPTION: main
E/AndroidRuntime: Process: com.javacodegeeks.androidvideocaptureexample, PID: 8350
E/AndroidRuntime: java.lang.IllegalStateException
E/AndroidRuntime: at android.media.MediaRecorder.start(Native Method)
E/AndroidRuntime: at com.javacodegeeks.androidvideocaptureexample.AndroidVideoCaptureExample.faceDetect(AndroidVideoCaptureExample.java:141)
E/AndroidRuntime: at com.javacodegeeks.androidvideocaptureexample.CameraPreview$1.onFaceDetection(CameraPreview.java:105)
E/AndroidRuntime: at android.hardware.Camera$EventHandler.handleMessage(Camera.java:1015)
E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime: at android.os.Looper.loop(Looper.java:146)
E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5635)
E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
CameraPreview.surfaceDestroyed（）释放相机，但未设置size-1。从后台调用应用时，可能会跳过 AndroidVideoCaptureExample.onCreate（），因此将使用带有旧 mCamera 引用的 mPreview 对象。现在，如果在 AndroidVideoCaptureExample.onResume（）之前执行 surfaceChanged（），则会调用 mPreview.refreshCamera（mCamera）; ，那就搞砸了。
简单的解决方法是将mCamera = null;添加到 CameraPreview.surfaceDestroyed（），并在 CameraPreview.refreshCamera（相机相机）的开头检查mCamera = null;
BTW， CameraPreview.surfaceCreated（）包含一些损坏的代码：
if (camera == null) { return; }您可以简单地删除所有这些块，这些操作将在 refreshChanged（）调用的 refreshCamera（）中执行。
您还可以从 CameraPreview 构造函数中删除第二个参数。
答案 1 :(得分：0)
删除那些<变量，看看是否能解决您的问题。当您的上一个活动完成后，Android框架可能会使进程和VM保持活动状态，以便在您下次启动应用程序时减少启动开销。发生这种情况时，您的所有static变量都将保留旧值。 （您的static实例也可能会被保留，因此请注意在那里放置任何数据，并且在您的应用启动时永远不要指望Application被调用。）