给出一个参考性的 按钮状态配置文件. 正常态, 选择态,获得焦点状态,按下态
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<!-- No states -->
<item android:state_focused="false" android:state_selected="false"
android:state_pressed="false" android:state_enabled="true"
android:drawable="@drawable/book_shop_normal" />
<!-- selected state -->
<item android:state_focused="false" android:state_selected="true"
android:state_pressed="false" android:state_enabled="true"
android:drawable="@drawable/book_shop_normal" />
<!-- Focused states -->
<item android:state_focused="true" android:state_selected="false"
android:state_pressed="false" android:state_enabled="true"
android:drawable="@drawable/book_shop_focus" />
<!-- Pressed -->
<item android:state_focused="false" android:state_selected="false"
android:state_pressed="true" android:state_enabled="true"
android:drawable="@drawable/book_shop_press" />
</selector>