Spring 读取配置文件得到ApplicationContext

在spring项目中做测试的话,获得spring中定义的bean实例(对象).可以用:

方法一:
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
ac.getBean("beanName");

方法二:
ApplicationContext ac = new FileSystemXmlApplicationContext("applicationContext.xml");
ac.getBean("beanName");

方法三:
ApplicationContext ac = WebApplicationContextUtils.getWebApplicationContext(ServletContext sc);
ac.getBean("beanName");