android使用shape做selector按钮按下和弹起的动画

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"><shape>
            <solid android:color="@color/color_E9E9E9"/>  
            <!-- 描边 -->
            <stroke android:width="1dp" android:color="@color/color_DDDDDD" />
            <!-- 圆角 -->
            <corners android:radius="0dp" />
        </shape></item>
    <item android:state_focused="true"><shape>
            <stroke android:width="1dp" android:color="@color/color_DDDDDD" />
            <corners android:radius="0dp" />
        </shape></item>
    <item><shape>
        <solid android:color="@color/color_F7F7F7"/> 
            <stroke android:width="1dp" android:color="@color/color_DDDDDD" />
            <corners android:radius="0dp" />
        </shape></item>
</selector>