Android——ImageButton按下效果设计

<selector xmlns:android="http://schemas.android.com/apk/res/android ">???
??? <item?????????? android:state_pressed="false"? android:drawable="@drawable/button_add" />???
??? <item?????????? android:state_pressed="true"?? android:drawable="@drawable/button_add_pressed" />???
??? <item?????????? android:state_focused="true"??? android:drawable="@drawable/button_add_pressed" />???
<item?????????? android:drawable="@drawable/button_add" />???
</selector>???
?
<?xml version="1.0" encoding="UTF-8"?>?
<selector xmlns:android="http://schemas.android.com/apk/res/android ">?
<item?????????? android:state_pressed="false"? android:drawable="@drawable/button_add" />?
?
??? <item??????????? android:state_pressed="true"? android:drawable="@drawable/button_add_pressed" />?
??? <item??????????? android:state_focused="true"? android:drawable="@drawable/button_add_pressed" />?
??? <item???????????? android:drawable="@drawable/button_add" />?
</selector>??

</ImageButton>???
<ImageButton?
??????????????????????? android:id="@+id/ImageButton"?
??????????????????????? android:layout_width="wrap_content"?
??????????????????????? android:layout_height="wrap_content"?
??????????????????????? android:background="#00000000"?
??????????????????????? android:src="@drawable/button_add_x" >?
</ImageButton>?

?