1、R-Drawable
Resources resources = mContext.getResources();
Drawable drawable = resources.getDrawable(R.drawable.a);
imageview.setBackground(drawable);
2、R-Bitmap
Resources r = this.getContext().getResources();
InputStream is = r.openRawResource(R.drawable.my_background_image);
BitmapDrawable bmpDraw = new BitmapDrawable(is);
Bitmap bmp = bmpDraw.getBitmap();
3、R-Bitmap
Bitmap bmp = BitmapFactory.decodeResource(r, R.drawable.icon);
Bitmap newb = Bitmap.createBitmap( 300, 300, Config.ARGB_8888 );
4、R-Bitmap
InputStream is = getResources().openRawResource(R.drawable.icon);
Bitmap mBitmap = BitmapFactory.decodeStream(is);