android ImageView 频繁切换图片 OOM

最近在帮一个朋友写一个android 软件，频繁的用ImageView 更换图片。
结果常常出现OOM
后来修改把ImageView加载图片自己来管理，问题解决了，不敢独享，拿出来与各位同学分享

private void showImage(int index) {
int resid = R.drawable.circle_01;
switch (index) {
case 1:
resid = R.drawable.circle_01;
break;
case 2:
resid = R.drawable.circle_02;
break;
case 3:
resid = R.drawable.circle_03;
break;
case 4:
resid = R.drawable.circle_04;
break;
case 5:
resid = R.drawable.circle_05;
break;
case 6:
resid = R.drawable.circle_06;
break;
case 7:
resid = R.drawable.circle_07;
break;
case 8:
resid = R.drawable.circle_08;
break;
case 9:
resid = R.drawable.circle_09;
break;
case 10:
resid = R.drawable.circle_10;
break;
case 11:
resid = R.drawable.circle_11;
break;
case 12:
resid = R.drawable.circle_12;
break;
}

//把历史的ImageView 图片对象（image_)释放
BitmapDrawable bitmapDrawable = (BitmapDrawable)image_.getBackground();
if(bitmapDrawable!=null){
Bitmap hisBitmap = bitmapDrawable.getBitmap();
if(hisBitmap.isRecycled()==false)
{
hisBitmap.recycle();
}
}
//上面的代码一定要做，否则不会超过30分钟可定会出现exit,当然我的timer设置的时间比较短。。。。。timer.schedule(task, 5, 5);

//下面代码是网上通常搜到的源码例子，但是不能解决，智能优化，只有加上上面的才能彻底解决内存的问题。
BitmapFactory.Options options =
new BitmapFactory.Options();
options.inPurgeable =
true; // bitmap can be purged to disk
options.inInputShareable =
true;
Bitmap bm = BitmapFactory.decodeStream(getResources().openRawResource(
resid));
Drawable bd = new BitmapDrawable(getResources(), bm);
image_.setBackgroundDrawable(bd);

}