精确监听ListView滑动到底部

main.xml如下:

<RelativeLayout 
    xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

    <ListView
        android:id="@+id/listView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_centerInParent="true"
     />

</RelativeLayout><RelativeLayout 
    xmlns:androi