使用web.xml方式加载Spring时，获取Spring context的两种方式

1、servlet方式加载

<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext</param-value>
</init-param>
</servlet>

ServletContext context = getServletContext();

XmlWebApplicationContext applicationContext = (XmlWebApplicationContext) context.getAttribute("org.springframework.web.servlet.FrameworkServlet.CONTEXT.dispatcherServlet");

DataSource dataSource=(DataSource)applicationContext.getBean("dataSource");

2、listener方式加载

<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext</param-value>
</context-param>
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>

ServletContext context = getServletContext();

WebApplicationContext applicationContext  = WebApplicationContextUtils
.getWebApplicationContext(context);

DataSource dataSource=(DataSource)applicationContext.getBean("dataSource");