Android如何使用selector设置RelativeLayout的背景

<RelativeLayout
            android:id="@+id/ly_text"
            android:clickable="true"
            android:layout_width="match_parent"
            android:layout_height="45dp"
            android:layout_below="@+id/blankview"
            android:background="@drawable/common_raw"
            android:orientation="horizontal">


<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/bg_white" android:state_pressed="false"/>
    <item android:drawable="@color/lightblue" />
</selector>

要有android:clickable="true"

selector里面的未选中的item要放在上面，不能颠倒