drawable animation 循环播放

<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:oneshot="true">
    <item android:drawable="@drawable/a" android:duration="2000"/>
    <item android:drawable="@drawable/b" android:duration="2000" />
    <item android:drawable="@drawable/c" android:duration="2000" />
    <item android:drawable="@drawable/d" android:duration="2000" />
</animation-list>

把android:oneshot="true"设置成android:oneshot="false"