spring配置文件加载

    spring为ApplicationContext提供的3种实现分别为：ClassPathXmlApplicationContext，FileSystemXmlApplicationContext和XmlWebApplicationContext，其中XmlWebApplicationContext是专为Web。xml。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);

<listener>

<listener-class>        org.springframework.web.context.ContextLoaderListener </listener-class>

 </listener> 或：

<servlet>    

<servlet-name>context</servlet-name>   

 <servlet-class>        org.springframework.web.context.ContextLoaderServlet     </servlet-class>  

<load-on-startup>1</load-on-startup> </servlet>       

 通过以上配置，Web容器会自动加载/WEB-INF/applicationContext.xml初始化 ApplicationContext实例，如果需要指定配置文件位置，可通过context-param加以指定：

 <context-param>    

 <param-name>contextConfigLocation</param-name>    

<param-value>/WEB-INF/myApplicationContext.xml</param-value> </context-param>       

 配置完成之后，即可通过

WebApplicationContextUtils.getWebApplicationContext方法在Web应用中获取ApplicationContext引用。

 如：ApplicationContext ctx=WebApplicationContextUtils.getWebApplicationContext(servletContext);     LoginAction action=(LoginAction)ctx.getBean("action");