Screen orientation lock

Is there a reliable way to lock screen orientation on all Android devices? The code below works for my Nexus S and other phones, but for some reason ROTATION_90 corresponds to SCREEN_ORIENTATION_REVERSE_PORTRAIT on the Xoom.

Is there any way to reliably map rotation to orientation?

private void lockScreenOrientation() {
    if (!mScreenOrientationLocked) {
        final int orientation = getResources().getConfiguration().orientation;
        final int rotation = getWindowManager().getDefaultDisplay().getOrientation();

        if (rotation == Surface.ROTATION_0 || rotation == Surface.ROTATION_90) {
            if (orientation == Configuration.ORIENTATION_PORTRAIT) {
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
            }
            else if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
            }
        }
        else if (rotation == Surface.ROTATION_180 || rotation == Surface.ROTATION_270) {
            if (orientation == Configuration.ORIENTATION_PORTRAIT) {
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT);
            }
            else if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE);
            }
        }

        mScreenOrientationLocked = true;
    }
}

private void unlockScreenOrientation() {
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);
    mScreenOrientationLocked = false;
}

EDIT: This code is meant to get the current orientation and lock it. The orientation is locked temporarily, and then released to the user.