Difference between applicationContext.xml and spring-servlet.xml in Spring
04-02-2015
QUESTION:
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?
Note: For example, mvc-dispatcher-servlet.xml is an spring-servlet.xml file.
ANSWER 1:
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.
ANSWER 2
One more point I want to add. In spring-servlet.xml we include component scan for Controller package. In following example we include filter annotation for controller package.
In applicationcontext.xml we add filter for remaining package excluding controller.
Debate:
why ? Why not just scan the whole thing one time ? – NimChimpsky Aug 14 '12 at 9:57
@NimChimpsky You have to scan @Controller beans in servlet context (required by Spring MVC). – Tuukka Mustonen Nov 21 '12 at 12:22
Why not can the whole thing twice? Why include/exclude? – Mike Rylander Jul 5 '13 at 16:26
One should also add use-default-filters="false" attribute in spring-servlet.xml – Rakesh Waghela Feb 25 '14 at 9:51
Rakesh Waghela has point. Without that attribute Controller beans will be created twice. Firstly in appContext and secondly in servletContext –
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?
Note: For example, mvc-dispatcher-servlet.xml is an spring-servlet.xml file.
ANSWER 1:
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.
ANSWER 2
One more point I want to add. In spring-servlet.xml we include component scan for Controller package. In following example we include filter annotation for controller package.
<!-- Scans for annotated @Controllers in the classpath -->
<context:component-scan base-package="org.test.web">
<context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>
In applicationcontext.xml we add filter for remaining package excluding controller.
<context:component-scan base-package="org.test">
<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>
Debate:
why ? Why not just scan the whole thing one time ? – NimChimpsky Aug 14 '12 at 9:57
@NimChimpsky You have to scan @Controller beans in servlet context (required by Spring MVC). – Tuukka Mustonen Nov 21 '12 at 12:22
Why not can the whole thing twice? Why include/exclude? – Mike Rylander Jul 5 '13 at 16:26
One should also add use-default-filters="false" attribute in spring-servlet.xml – Rakesh Waghela Feb 25 '14 at 9:51
Rakesh Waghela has point. Without that attribute Controller beans will be created twice. Firstly in appContext and secondly in servletContext –
