获取applicationContext的几个类

1, ApplicationContext ac = new FileSystemXmlApplicationContex("src/ applicationContext.xml"); //

2, WebApplicationContext ctx = null;
??? if (ctx == null)?
??? {?
??? ctx = WebApplicationContextUtils?
??? .getRequiredWebApplicationContext(this.getServletContext());
????
??? }?

3, ApplicationContext ac = new ... ClassPathXmlApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");?

4, WebApplicationContext wac = (WebApplicationContext)servletContext.

　　getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);