@Override
public void onResume() {
    super.onResume();
    getView().setFocusableInTouchMode(true);
    getView().requestFocus();
    getView().setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View view, int i, KeyEvent keyEvent) {
            if(keyEvent.getAction() == KeyEvent.ACTION_DOWN && i == KeyEvent.KEYCODE_BACK){
                Toast.makeText(getActivity(), "按了返回键", Toast.LENGTH_SHORT).show();
                return true;
            }
            return false;
        }
    });
}