Android利用layer-list实现ProgressBar

布局文件如下

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:indeterminateBehavior="repeat"
        android:indeterminateDrawable="@drawable/progress_big" /> 


</RelativeLayout>

progress_big.xml文件:

<!--多图层图片-->
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item >
        <rotate android:drawable="@mipmap/spinner_big_inner" android:fromDegrees="1080" android:toDegrees="0"></rotate>
    </item>

    <item >
        <rotate android:drawable="@mipmap/spinner_big_outer" android:fromDegrees="0" android:toDegrees="720"></rotate>
    </item>
</layer-list>

上面引用的图片是这两张:

spinner_big_inner.png spinner_big_outer.png

layer-list具有图层叠加的效果,所以只要一张图片逆时针旋转,一张图片顺时针旋转即可实现这种效果:

newloading.gif