android 圆形进度条（旋转的等待动画）

<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
android:fromDegrees="0"
android:pivotX="50%"
android:pivotY="50%"
android:toDegrees="360">
<shape android:innerRadiusRatio="3"
android:shape="ring"
android:thicknessRatio="8"
android:useLevel="false">
<gradient android:centerColor="@color/color_orange"
android:centerY="0.5"
android:endColor="@color/white"
android:useLevel="false"/>
</shape>

</rotate>

<ProgressBarandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerInParent="true"style="?android:attr/progressBarStyleSmall"android:indeterminateDrawable="@drawable/progress_small"/>