android按钮按下的效果
xml文件名为 ic_tab_artists
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/android_pressed"
android:state_pressed="true" />
<item android:drawable="@drawable/android_focused"
android:state_focused="true" />
<item android:drawable="@drawable/android_normal" />
</selector>


<ImageButton
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@drawable/ic_tab_artists"
/>