我在官方developer.android.com教程的帮助下实现了一个Android摄像头。该应用程序有时工作正常，但大约3/5倍的相机预览在一些旋转和点击按钮后冻结甚至没有这些工作（其他元素不冻结）。最可爱的部分是，当我调试应用程序时，预览不会卡住，但是当我想要正常运行应用程序时，问题就会发生。
这是我的fullScreen类，它包含android studio为fullScreen活动生成的代码以及实现surfaceHolder.Callback和相机内容的代码。
public class CameraActivity extends Activity implements SurfaceHolder.Callback {
... // some constants here
private Camera mCamera;
private SurfaceHolder mHolder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
SurfaceView cameraSufaceView = (SurfaceView) findViewById(R.id.camera_preview);
// Accessing front camera to take picture
mCamera = openFrontFacingCameraGingerbread();
if (mCamera != null) {
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = cameraSufaceView.getHolder();
mHolder.addCallback(this);
} else {
// Alter user
}
/**
* Gets an instance of front facing camera if available
*/
@SuppressWarnings("deprecation")
private Camera openFrontFacingCameraGingerbread() {
int cameraCount;
Camera cam = null;
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
cameraCount = Camera.getNumberOfCameras();
for (int camIdx = 0; camIdx < cameraCount; camIdx++) {
Camera.getCameraInfo(camIdx, cameraInfo);
if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
try {
cam = Camera.open(camIdx);
} catch (RuntimeException e) {
Log.e(TAG, "Camera failed to open: " + e.getLocalizedMessage());
}
}
}
return cam;
}
@Override
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());
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// 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
}
// start preview with new settings
try {
// mCamera.setDisplayOrientation(needs degree here);
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e) {
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
releaseCamera();
}
@Override
protected void onPause() {
super.onPause();
releaseCamera();
}
@Override
protected void onResume() {
super.onResume();
if (mCamera == null)
mCamera = openFrontFacingCameraGingerbread();
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
当出现此问题时，LogCat中会出现一些错误，但它们并不能提供真正的信息。他们是：
26893-26893/com.naviiid.retinaflash E/art﹕ No implementation found for void java.lang.Runtime.appStartupEnd() (tried Java_java_lang_Runtime_appStartupEnd and Java_java_lang_Runtime_appStartupEnd__)
09-16 01:34:09.336 26893-26893/com.naviiid.retinaflash E/ActivityThread﹕ appStartupEnd :
java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at android.app.ActivityThread.appStartupEnd(ActivityThread.java:305)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2819)
at android.app.ActivityThread.access$900(ActivityThread.java:177)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
Caused by: java.lang.UnsatisfiedLinkError: No implementation found for void java.lang.Runtime.appStartupEnd() (tried Java_java_lang_Runtime_appStartupEnd and Java_java_lang_Runtime_appStartupEnd__)
at java.lang.Runtime.appStartupEnd(Native Method)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at android.app.ActivityThread.appStartupEnd(ActivityThread.java:305)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2819)
at android.app.ActivityThread.access$900(ActivityThread.java:177)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
到目前为止我发现的唯一线索是，即使活动没有暂停，有时android会调用onPause方法。为了再次获取相机的实例，我在onResume方法中调用openFrontFacingCameraGingerbread()。