我们可以这样写

Activity

ImageView img = findViewById(R.id.img);
String text = "tupianmingcheng";
img.setBackgroundResource(getResource().getIdentifier(text, "drawable", getPackageName()));

adapter，注意context

String text = "tupianmingcheng";
img.setBackgroundResource(context.getResource().getIdentifier(text, "drawable", context.getPackageName()));

Fragment，注意：需要getContext()

String text = "tupianmingcheng";
img.setBackgroundResource(getContext().getResource().getIdentifier(text, "drawable", getContext().getPackageName()));