1、android:focusable="true"

 <GridView
            android:id="@+id/gv_device"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:numColumns="3"
            android:horizontalSpacing="20dp"
            android:verticalSpacing="50dp"
            android:layout_margin="50dp"
            android:focusable="true"
            />
 

2、item selector

state_selected尤為重要，上下左右切換就靠這個屬性

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_focused="true" android:drawable="@mipmap/xuanzhe"></item>
    <item android:state_pressed="true" android:drawable="@mipmap/xuanzhe"></item>
    <item android:state_selected="true" android:drawable="@mipmap/xuanzhe"></item>
</selector>