通过asset获取bitmap
private Bitmap getBitmapFromAsset(Context context, String strName) {
AssetManager assetManager = context.getAssets();
InputStream istr;
Bitmap bitmap = null;
try {
istr = assetManager.open(strName);
bitmap = BitmapFactory.decodeStream(istr);
} catch (IOException e) {
return null;
}
return bitmap;
}