<rotate //旋转动画xmlns:android="http://schemas.android.com/apk/res/android"

    android:fromDegrees="0"

    android:pivotX="50%"

    android:pivotY="50%"  //旋转中心

    android:toDegrees="360" >

    <shape//形状

        android:innerRadius="15dp"//半径

        android:shape="ring"//圆

        android:thickness="3dp"//厚度

        android:useLevel="false" >

        <gradient

            android:centerColor="#5f00"

            android:endColor="#fff"

            android:startColor="#f00"

            android: ="sweep" />//扫描线渐变

    </shape>

</rotate>