/**
 * 查询多条数据
 */
private void query() {
    BmobQuery<Category> bmobQuery = new BmobQuery<>();
    bmobQuery.findObjects(new FindListener<Category>() {
        @Override
        public void done(List<Category> categories, BmobException e) {
            if (e == null) {
                Snackbar.make(mBtnQuery, "查询成功：" + categories.size(), Snackbar.LENGTH_LONG).show();
            } else {
                Log.e("BMOB", e.toString());
                Snackbar.make(mBtnQuery, e.getMessage(), Snackbar.LENGTH_LONG).show();
            }
        }
    });
}