Android按钮点击效果的实现(selector)

<?xml version="1.0" encoding="utf-8"?>
<!-- "@drawable/ok1"表示未点击按钮时的图片 -->
<!-- "@drawable/ok2"表示点击按钮时的图片 -->
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:state_pressed="false"
android:drawable="@drawable/ok1"
/>
<item
android:state_pressed="true"
android:drawable="@drawable/ok2"
/>
</selector>

<?xml version="1.0" encoding="utf-8"?>
<!-- android:background="@layout/ok_selector"图片的背景 -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ImageButton
android:id="@+id/ImageButton1"
android:background="@layout/ok_selector"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="visible"
/>
</LinearLayout>