android doc中是这样描述的：
public void setImageResource (int resId)
这是其中的一个方法，参数resld是这样：
ImageView.setImageResource(R.drawable.icon);
看下面这段话
Sets a drawable as the content of this ImageView.
This does Bitmap reading and decoding on the UI thread, which can cause a latency hiccup. If that's a concern, consider usingsetImageDrawable(Drawable) or setImageBitmap(Bitmap) and BitmapFactory instead.
此函数使用UI线程，可以用下面3种替代：
ImageView iv;
String fileName = "/data/data/com.test/aa.png;
Bitmap bm = BitmapFactory.decodeFile(fileName);
iv.setImageBitmap(bm);
ImageView iv = new ImageView(context);
iv.setImageResource(iv[position]);
iv.setScaleType(ImageView.ScaleType.FIT_XY);
iv.setLayoutParams(new Gallery.LayoutParams(136,88));
mImageView = (ImageView)this.findViewById(R.id.myImageView1);
mImageView.setImageDrawable(getResources().getDrawable(R.drawable.right)