Spring中的ApplicationContext是父子層次結構的，在存在多個上下文時，會有一個根上下文，作為其他上下文的“父親”。：
<Listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
複製程式碼如上，如果在web.xml檔案中使用Listener監聽器來載入Spring的配置，Spring會建立一個全域性的WebApplicationContext上下文，此上下文被稱為根上下文，儲存在ServletContext中。
public interface WebApplicationContext extends ApplicationContext {
/**
* Context attribute to bind root WebApplicationContext to on successful startup.
* <p>Note: If the startup of the root context fails, this attribute can contain
* an exception or error as value. Use WebApplicationContextUtils for convenient
* lookup of the root WebApplicationContext.
* @see org.springframework.web.context.support.WebApplicationContextUtils#getWebApplicationContext
* @see org.springframework.web.context.support.WebApplicationContextUtils#getRequiredWebApplicationContext
*/
String ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE = WebApplicationContext.class.getName() + ".ROOT";
/**
* Scope identifier for request scope: "request".
* Supported in addition to the standard scopes "singleton" and "prototype".
*/
String SCOPE_REQUEST = "request";
/**
* Scope identifier for session scope: "session".
* Supported in addition to the standard scopes "singleton" and "prototype".
*/
String SCOPE_SESSION = "session";
/**
* Scope identifier for global session scope: "globalSession".
* Supported in addition to the standard scopes "singleton" and "prototype".
*/
String SCOPE_GLOBAL_SESSION = "globalSession";
/**
* Scope identifier for the global web application scope: "application".
* Supported in addition to the standard scopes "singleton" and "prototype".
*/
String SCOPE_APPLICATION = "application";
/**
* Name of the ServletContext environment bean in the factory.
* @see javax.servlet.ServletContext
*/
String SERVLET_CONTEXT_BEAN_NAME = "servletContext";
/**
* Name of the ServletContext/PortletContext init-params environment bean in the factory.
* <p>Note: Possibly merged with ServletConfig/PortletConfig parameters.
* ServletConfig parameters override ServletContext parameters of the same name.
* @see javax.servlet.ServletContext#getInitParameterNames()
* @see javax.servlet.ServletContext#getInitParameter(String)
* @see javax.servlet.ServletConfig#getInitParameterNames()
* @see javax.servlet.ServletConfig#getInitParameter(String)
*/
String CONTEXT_PARAMETERS_BEAN_NAME = "contextParameters";
/**
* Name of the ServletContext/PortletContext attributes environment bean in the factory.
* @see javax.servlet.ServletContext#getAttributeNames()
* @see javax.servlet.ServletContext#getAttribute(String)
*/
String CONTEXT_ATTRIBUTES_BEAN_NAME = "contextAttributes";
/**
* Return the standard Servlet API ServletContext for this application.
* <p>Also available for a Portlet application, in addition to the PortletContext.
*/
ServletContext getServletContext();
}
複製程式碼其中，key為org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUT屬性的值。
在很多情況下，我們還會配置一個或者多個DispatcherServlet，每個DispatcherServlet都有一個自己的WebApplicationContext上下文。這個上下文是私有的，繼承了根上下文的所有內容，該上下文儲存在ServletContext中，key是org.springframework.web.servlet.FrameworkServlet#SERVLET_CONTEXT_PREFIX的值+servlet名稱。當一個Request物件產生時，會把這個WebApplicationContext上下文儲存在Request物件中。
DispatcherServlet載入Srping配置。