怎么用代码设置ImageView的src，图片在drawable里

我知道用setImageDrawable()，可是这个drawable=？

drawable对象，有多种，比如这里用BitmapDrawable

 1、从资源中获取Drawble
private BitmapDrawable getDrawableFromId(int id){  //这个id就是类似R.drawable.lander_firing
    Resources res = getResources();  
    return (BitmapDrawable)res.getDrawable(id);  
}  
2、从资源中获取Bitmap图像
private Bitmap getBitmapFromId(int id){  
    Resources res = getResources();  
    BitmapDrawable bitDraw = new BitmapDrawable(res.openRawResource(R.drawable.lander_firing));  
    Bitmap bm = bitDraw.getBitmap();  
    return bm;  
    //mImageView.setImageBitmap(bm);  
}  

R.drawable.图片

R.Drawable.ImageID

imageView.setBackgroundResource(R.drawable.XX);

imageView.setBackgroundResource(R.drawable.XX);