问Nexus 4相机不开

EN

SurfaceHolder mHolder;
public Camera camera;
int mCameraId;

Preview(Context context) {
    super(context);

    mHolder = getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
    camera = Camera.open();
    camera.setDisplayOrientation(90);

    try {
        if (camera != null) {
            camera.setPreviewDisplay(holder);

            camera.setPreviewCallback(new PreviewCallback() {

                public void onPreviewFrame(byte[] data, Camera arg1) {
                    FileOutputStream outStream = null;
                    try {
                        Log.d(TAG, "onPreviewFrame - wrote bytes: "
                                + data.length);
                    } finally {
                    }
                    Preview.this.invalidate();
                }
            });
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void surfaceDestroyed(SurfaceHolder holder) {
    camera.stopPreview();
    camera.release();
    camera = null;
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    Camera.Parameters parameters = camera.getParameters();
    parameters.setPreviewSize(w, h);
    camera.setParameters(parameters);
    camera.startPreview();
}

@Override
public void draw(Canvas canvas) {
    super.draw(canvas);
    Paint p = new Paint(Color.RED);
    Log.d(TAG, "draw");
    canvas.drawText("PREVIEW", canvas.getWidth() / 2,
            canvas.getHeight() / 2, p);
}