android AnimationDrawable类实现动画效果

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="#000000"
    tools:context=".MainActivity" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</RelativeLayout>

package com.playgif;

import android.app.Activity;
import android.graphics.drawable.AnimationDrawable;
import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends Activity {

    ImageView imageView = null;
    AnimationDrawable animation = null;;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView = (ImageView)findViewById(R.id.imageView1);
        imageView.setBackgroundResource(R.drawable.img_list);
        animation = (AnimationDrawable)imageView.getBackground();
        //是否仅启动一次 
        animation.setOneShot(false);  
        if(animation.isRunning())
        {  
            animation.stop();//停止   
        }  
        animation.start();//启动 
        
    }
}

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/a1" android:duration="100" />   
    <item android:drawable="@drawable/a2" android:duration="100" />   
    <item android:drawable="@drawable/a3" android:duration="100" />  
    <item android:drawable="@drawable/a4" android:duration="100" />  
    <item android:drawable="@drawable/a5" android:duration="100" />  
    <item android:drawable="@drawable/a6" android:duration="100" /> 
    <item android:drawable="@drawable/a7" android:duration="100" />   
    <item android:drawable="@drawable/a8" android:duration="100" />   
    <item android:drawable="@drawable/a9" android:duration="100" />  
    <item android:drawable="@drawable/a10" android:duration="100" />  
    <item android:drawable="@drawable/a11" android:duration="100" />  
    <item android:drawable="@drawable/a12" android:duration="100" /> 
</animation-list>