What is the difference between ApplicationContext and WebApplicationContext in Spring MVC

Question

What is the difference between Application Context and Web Application Context   I am aware that WebApplicationContext is used for Spring MVC architecture oriented applications   I want to know what is the use of ApplicationContext in MVC applications  And what kind of beans are defined in ApplicationContext

User · Answer

ApplicationContext  Root Application Context    Every Spring MVC web application has an applicationContext xml file which is configured as the root of context configuration  Spring loads this file and creates an applicationContext for the entire application  This file is loaded by the ContextLoaderListener which is configured as a context param in web xml file  And there will be only one applicationContext per web application   WebApplicationContext   WebApplicationContext is a web aware application context i e  it has servlet context information  A single web application can have multiple WebApplicationContext and each Dispatcher servlet  which is the front controller of Spring MVC architecture  is associated with a WebApplicationContext  The webApplicationContext configuration file  -servlet xml is specific to a DispatcherServlet   And since a web application can have more than one dispatcher servlet configured to serve multiple requests  there can be more than one webApplicationContext file per web application

User · Answer

Web application context  specified by the WebApplicationContext interface  is a Spring application context for a web applications  It has all the properties of a regular Spring application context  given that the WebApplicationContext interface extends the ApplicationContext interface  and add a method for retrieving the standard Servlet API ServletContext for the web application   In addition to the standard Spring bean scopes singleton and prototype  there are three additional scopes available in a web application context    request - scopes a single bean definition to the lifecycle of a single HTTP request  that is  each HTTP request has its own instance of a bean created off the back of a single bean definition session - scopes a single bean definition to the lifecycle of an HTTP Session application - scopes a single bean definition to the lifecycle of a ServletContext

User · Answer

Web Application context extended Application Context which is designed to work with the standard javax servlet ServletContext so it s able to communicate with the container     public interface WebApplicationContext extends ApplicationContext       ServletContext getServletContext        Beans  instantiated in WebApplicationContext will also be able to use ServletContext if they implement ServletContextAware interface   package org springframework web context  public interface ServletContextAware extends Aware         void setServletContext ServletContext servletContext       There are many things possible to do with the ServletContext instance  for example accessing WEB-INF resources xml configs and etc   by calling the getResourceAsStream   method  Typically all application contexts defined in web xml in a servlet Spring application are Web Application contexts  this goes both to the root webapp context and the servlet s app context   Also  depending on web application context capabilities may make your application a little harder to test  and you may need to use MockServletContext class for testing   Difference between servlet and root context Spring allows you to build multilevel application context hierarchies  so the required bean will be fetched from the parent context if it s not present in the current application context  In web apps as default there are two hierarchy levels  root and servlet contexts      This allows you to run some services as the singletons for the entire application  Spring Security beans and basic database access services typically reside here  and another as separated services in the corresponding servlets to avoid name clashes between beans  For example one servlet context will be serving the web pages and another will be implementing a stateless web service   This two level separation comes out of the box when you use the spring servlet classes  to configure the root application context you should use context-param tag in your web xml   lt context-param gt       lt param-name gt contextConfigLocation lt  param-name gt       lt param-value gt           WEB-INF root-context xml              WEB-INF applicationContext-security xml      lt  param-value gt   lt  context-param gt     the root application context is created by ContextLoaderListener which is declared in web xml   lt listener gt           lt listener-class gt org springframework web context ContextLoaderListener lt  listener-class gt       lt  listener gt       and servlet tag for the servlet application contexts   lt servlet gt      lt servlet-name gt myservlet lt  servlet-name gt      lt servlet-class gt org springframework web servlet DispatcherServlet lt  servlet-class gt      lt init-param gt         lt param-name gt contextConfigLocation lt  param-name gt         lt param-value gt app-servlet xml lt  param-value gt      lt  init-param gt   lt  servlet gt    Please note that if init-param will be omitted  then spring will use myservlet-servlet xml in this example   See also  Difference between applicationContext xml and spring-servlet xml in Spring Framework

User · Answer

Going back to Servlet days  web xml can have only one  lt context-param gt   so only one context object gets created when server loads an application and the data in that context is shared among all resources  Ex  Servlets and JSPs   It is same as having Database driver name in the context  which will not change  In similar way  when we declare contextConfigLocation param in  lt contex-param gt  Spring creates one Application Context object     lt context-param gt         lt param-name gt contextConfigLocation lt  param-name gt         lt param-value gt com myApp ApplicationContext lt  param-value gt    lt  context-param gt    You can have multiple Servlets in an application  For example you might want to handle  secure   requests in one way and  non-seucre   in other way  For each of these Servlets you can have a context object  which is a WebApplicationContext    lt servlet gt       lt servlet-name gt SecureSpringDispatcher lt  servlet-name gt       lt servlet-class gt org springframework web servlet DispatcherServlet lt  servlet-class gt       lt init-param gt           lt param-name gt contextClass lt  param-name gt           lt param-value gt com myapp secure SecureContext lt  param-value gt       lt  init-param gt   lt  servlet gt   lt servlet-mapping gt       lt servlet-name gt SecureSpringDispatcher lt  servlet-name gt       lt url-pattern gt  secure   lt  url-pattern gt   lt  servlet-mapping gt   lt servlet gt       lt servlet-name gt NonSecureSpringDispatcher lt  servlet-name gt       lt servlet-class gt org springframework web servlet DispatcherServlet lt  servlet-class gt       lt init-param gt           lt param-name gt contextClass lt  param-name gt           lt param-value gt com myapp non-secure NonSecureContext lt  param-value gt       lt  init-param gt   lt  servlet gt   lt servlet-mapping gt       lt servlet-name gt NonSecureSpringDispatcher lt  servlet-name gt       lt url-pattern gt  non-secure   lt  url-patten gt   lt  servlet-mapping gt

User · Answer

The accepted answer is through but there is official explanation on this   The WebApplicationContext is an extension of the plain ApplicationContext that has some extra features necessary for web applications  It differs from a normal ApplicationContext in that it is capable of resolving themes  see Using themes   and that it knows which Servlet it is associated with  by having a link to the ServletContext   The WebApplicationContext is bound in the ServletContext  and by using static methods on the RequestContextUtils class you can always look up the WebApplicationContext if you need access to it  Cited from Spring web framework reference  By the way servlet and root context are both webApplicationContext

[spring] What is the difference between ApplicationContext and WebApplicationContext in Spring MVC?

Examples related to spring

Examples related to spring-mvc

Examples related to applicationcontext