Spring Ioc 容器实例化容器

Spring Ioc 容器实例化容器如:
1).Resource resource = new FileSystemResource("beans.xml");
BeanFactory factory = new XmlBeanFactory(resource);

2).ClassPathResource resource = new ClassPathResource("beans.xml");
BeanFactory factory = new XmlBeanFactory(resource);

3).ApplicationContext context = new ClassPathXmlApplicationContext(
new String[] {"applicationContext.xml","applicationContext-part2.xml"});
BeanFactory factory = (BeanFactory)context;