加载器目前有两种选择:ContextLoaderListener和ContextLoaderServlet
只是一个是基于Servlet2.3版本中新引入的Listener接口实现,而另一个基于Servlet接口实现。开发中可根据目标Web容器的实际情况进行选择
在web.xml中增加
-
<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>
<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>classpath*:applicationContext-*.xml ,/WEB-INF/myApplicationContext.xml</param-value>
-
</context-param>
<context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath*:applicationContext-*.xml ,/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:
BeanFactory factory = WebApplicationContextUtils.getWebApplicationContext(request.getSession ().getServletContext());
UserManager userManager = (UserManager)factory.getBean("userManager");
实际上在 org.springframework.web.context.ContextLoaderServlet 、org.springframework.web.context.ContextLoaderListener 中实现了以下核心代码:
BeanFactory factory = new ClassPathXmlApplictionContext("applicationContext.xml");
创建IOC容器内配置的对象,并维护对像间的依赖关系.