没有配置监听器，加载器，和加载文件类时怎么得到bean

Resource res = new ClassPathResource("com/smart/beanfactory/beans.xml");  BeanFactory bf= new DefaultListableBeanFactory();  XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader((DefaultListableBeanFactory)bf);  reader.loadBeanDefinitions(res);