android button多状态， selector

<selector xmlns:android="http://schemas.android.com/apk/res/android" >   

<item           android:state_pressed="false"  android:drawable="@drawable/d_300_button_01" />     

<item           android:state_pressed="true"   android:drawable="@drawable/d_300_button_active_01" />     

<item           android:state_focused="true"    android:drawable="@drawable/d_300_button_active_01" />     

<item           android:drawable="@drawable/d_300_button_01" />    

</selector>