public class MainActivity extends Activity {
    Button centerButton;
    MapView mapView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create the main map view
        mapFragment = new MapFragment();
        mapFragment.setArguments(args);
        getFragmentManager().beginTransaction()
            .add(R.id.main_content, mapFragment).commit();
}

    /*
     * This function centers the map. It is just one of many
     * that stops working on device rotation.
     */
    public void centerMap(View view) {
            mapFragment.getMapView().getController().setCenter(new GeoPoint(12.0,0.0));
   Lod.d(TAG, "Reacting and working.");
    }
}

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/d_layout"
    >

    <!-- The main content view -->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:id="@+id/main_content">

</LinearLayout>

<LinearLayout
    android:baselineAligned="false"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
>

<!-- This is the layout for other control items-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:id="@+id/sub"
        android:layout_gravity="top"
        android:paddingLeft="20dp"
        android:paddingRight="20dp"
    >
    </LinearLayout>

</LinearLayout>


</RelativeLayout>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <org.osmdroid.MapView
        android:id="@+id/mapfragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tilesource="Mapnik"
    />
    <Button
        android:layout_gravity="right|bottom"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/center_button"
        android:text="center"
        android:onClick="centerMap"
    />
</FrameLayout>