spring为ApplicationContext提供的3种实现分别为：ClassPathXmlApplicationContext，FileSystemXmlApplicationContext和XmlWebApplicationContext，其中XmlWebApplicationContext是专为Web工程定制的。使用举例如下：
   1. FileSystemXmlApplicationContext
       eg1. ApplicationContext ctx = new FileSystemXmlApplicationContext("bean.xml"); //加载单个配置文件
       eg2.
               String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};
               ApplicationContext ctx = new FileSystemXmlApplicationContext(locations ); //加载单个配置文件
       eg3.    

    ApplicationContext ctx =new FileSystemXmlApplicationContext("D:/project/bean.xml");//根据具体路径加载文件
  2. ClassPathXmlApplicationContext
       eg1.  ApplicationContext ctx = new ClassPathXmlApplicationContext("bean.xml");
       eg2.
               String[] locations = {"bean1.xml", "bean2.xml", "bean3.xml"};
               ApplicationContext ctx = new ClassPathXmlApplication(locations);
       注：其中FileSystemXmlApplicationContext和ClassPathXmlApplicationContext与BeanFactory的xml文件定位方式一样是基于路径的。
 3. XmlWebApplicationContext
   eg1. ServletContext servletContext = request.getSession().getServletContext();    
        ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(servletContext);