android摄像头编程 onPictureTaken方法无法回调？？？？

public class MainActivity extends Activity implements SurfaceHolder.Callback {

protected static final int TAKE_PHOTO_WITH_DATA = 0;

private Button takeButton = null;

private Button identifyButton = null;

private SurfaceView cSurfaceView;

private SurfaceHolder sfh;

Camera camera;

@Override

protected void onDestroy() {

camera.startPreview();

camera.release();

super.onDestroy();

}

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

cSurfaceView = (SurfaceView) findViewById(R.id.surface_camera);

sfh = cSurfaceView.getHolder();

sfh.addCallback(this);

sfh.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

takeButton = (Button) findViewById(R.id.take_picture);

takeButton.setOnClickListener(new ButtonListner());

identifyButton = (Button) findViewById(R.id.identify_picture);

identifyButton.setOnClickListener(new ButtonListner());

}

public void onPictureTaken(byte[] data, Camera camera) {

System.out.println(camera);

}

class ButtonListner implements OnClickListener, Camera.PictureCallback {

public void onClick(View v) {

switch (v.getId()) {

case R.id.take_picture:

camera.takePicture(null, this, this, this);

break;

case R.id.identify_picture:

break;

}

}

public void onPictureTaken(byte[] data, Camera camera) {

System.out.println("takenpicture");

}

}

public void surfaceCreated(SurfaceHolder holder) {

camera = Camera.open();

try {

Camera.Parameters parameters = camera.getParameters();

if (this.getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE) {

// 这是一个众所周知但未文档化的特性

parameters.set("orientation", "portrait");

// 对于Android 2.2及以上版本

camera.setDisplayOrientation(90);

parameters.setRotation(90);

} else {

parameters.set("orientation", "landscape");

camera.setDisplayOrientation(0);

parameters.setRotation(0);

}

camera.setParameters(parameters);

camera.setPreviewDisplay(holder);

} catch (IOException exception) {

camera.release();

}

camera.startPreview();

}

public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

camera.startPreview();

}

public void surfaceDestroyed(SurfaceHolder holder) {

}

}