问软键盘上升时如何使按钮保持在底部

EN

<RelativeLayout>
     <RelativeLayout
        android:id="@+id/activity_form_button_frame"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true">
    <ImageButton
        android:id="@+id/activity_form_next_button"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@android:color/black"
        android:src="@drawable/next_btn_drawable"
        android:scaleType="fitCenter"
        android:padding="5dp"
        />
    <Button
        android:id="@+id/activity_form_sumbit_button"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@android:color/black"
        android:text="SUBMIT"
        android:textColor="@color/buttonBlue"
        android:visibility="gone"
        android:padding="15dp"
        style="@android:style/TextAppearance.Large"/>
    </RelativeLayout>

    <FrameLayout
        android:id="@+id/activity_form_fragmentcontainer"
        android:layout_below="@id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/activity_form_button_frame"/>

    </RelativeLayout>