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  • Are applicationContext.xml and spring-servlet.xml related anyhow in Spring Framework?
  • Will the properties files declared in applicationContext.xml be available to DispatcherServlet?
  • On a related note, why do I need a *-servlet.xml at all? Why is applicationContext.xml alone insufficient?

Spring lets you define multiple contexts in a parent-child hierarchy.
The applicationContext.xml defines the beans for the “root webapp context”, i.e. the context associated with the webapp.
The spring-servlet.xml (or whatever else you call it) defines the beans for one servlet’s app context. There can be many of these in a webapp, one per Spring servlet (e.g. spring1-servlet.xml for servlet spring1, spring2-servlet.xml for servlet spring2).
Beans in spring-servlet.xml can reference beans in applicationContext.xml, but not vice versa.
All Spring MVC controllers must go in the spring-servlet.xml context.
In most simple cases, the applicationContext.xml context is unnecessary. It is generally used to contain beans that are shared between all servlets in a webapp. If you only have one servlet, then there’s not really much point, unless you have a specific use for it.

Scenario 1

In client application (application is not web application, e.g may be swing app)

  1. private static ApplicationContext context = new  ClassPathXmlApplicationContext("test-client.xml");
  3. context.getBean(name);

No need of web.xml. ApplicationContext as container for getting bean service. No need for web server container. In test-client.xml there can be Simple bean with no remoting, bean with remoting.
Conclusion: In Scenario 1 applicationContext and DispatcherServlet are not related.

Scenario 2

In a server application (application deployed in server e.g Tomcat). Accessed service via remoting from client program (e.g Swing app)
Define listener in web.xml

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

At server startup ContextLoaderListener instantiates beans defined in applicationContext.xml.
Assuming you have defined the following in applicationContext.xml:

  1. <import resource="test1.xml" />
  2. <import resource="test2.xml" />
  3. <import resource="test3.xml" />
  4. <import resource="test4.xml" />

The beans are instantiated from all four configuration files test1.xml, test2.xml, test3.xml, test4.xml.
Conclusion: In Scenario 2 applicationContext and DispatcherServlet are not related.

Scenario 3

In a web application with spring MVC.
In web.xml define:

  1. <servlet>
  2.     <servlet-name>springweb</servlet-name>
  3.     <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    
  4. </servlet>
  6. <servlet-mapping>
  7.     <servlet-name>springweb</servlet-name>
  8.     <url-pattern>*.action</url-pattern>
  9. </servlet-mapping>

When Tomcat starts, beans defined in springweb-servlet.xml are instantiated. DispatcherServlet extends FrameworkServlet. In FrameworkServlet bean instantiation takes place for springweb . In our case springweb is FrameworkServlet.
Conclusion: In Scenario 3 applicationContext and DispatcherServlet are not related.

Scenario 4

In web application with spring MVC. springweb-servlet.xml for servlet and applicationContext.xml for accessing the business service within the server program or for accessing DB service in another server program.
In web.xml the following are defined:

  1. <listener>
  2.     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  3. </listener>
  5. <servlet>
  6.     <servlet-name>springweb</servlet-name>
  7.     <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>        
  8. </servlet>
  10. <servlet-mapping>
  11.     <servlet-name>springweb</servlet-name>
  12.     <url-pattern>*.action</url-pattern>
  13. </servlet-mapping>

At server startup, ContextLoaderListener instantiates beans defined in applicationContext.xml; assuming you have declared herein:

  1. <import resource="test1.xml" />
  2. <import resource="test2.xml" />
  3. <import resource="test3.xml" />
  4. <import resource="test4.xml" />

The beans are all instantiated from all four test1.xml, test2.xml, test3.xml, test4.xml. After the completion of bean instantiation defined in applicationContext.xml, beans defined in springweb-servlet.xml are instantiated.
So the instantiation order is: the root (application context), then FrameworkServlet.
Now it should be clear why they are important in which scenario.