someAnimObj.start()
someAnimObj.stop()  

可以很容易地实现这两种需求，但是如果单纯这样做的话，会出现一个问题：第二次播放的第一帧竟然是上次停止播放时候的最后一帧

搜索了一下，发现这个是Android帧动画的通病。现把解决方法写出来。

android 5.0以上的版本

Drawable drawable = mHeaderImage.getDrawable();
((AnimationDrawable) mHeaderImage.getDrawable()).stop();
mHeaderImage.setImageDrawable(null);
mHeaderImage.setImageDrawable(drawable);

android 5.0以下的版本

The API is a bit weird here, because the restart function is inside the setVisible function of AnimationDrawable. If you don‘t restart and just do another start() on an already finished animation - it will just jump to the last frame. You must reset the animation before starting it.

However if you do setVisible(true,true) your animation will run twice!, so you must dosetVisible(false,true);. This will reset the animation for a start() operation.

ImageView animateHere = (ImageView) findViewById(R.id.animate_here);
animateHere.setImageDrawable(((ImageView)findViewById(R.id.anim_preloaded_imgview).getDrawable());
AnimationDrawable anim = (AnimationDrawable) animateHere.getDrawable();
anim.setVisible(false, true); //reset! see previous section
anim.start(); //now good to start, even if already fired before

　这种方法在5.0以上有没有效果了。所以把这两种方法都用上，就可以兼容这两个版本了。