WebApplicationInitializer
is used to configure ServletContext programatically. SpringServletContainerInitializer
detect the classes that implements WebApplicationInitializer interface on
application start up time.
HelloWorldController.java
hello.jsp
myWebAppConfigurations.xml
Traditional XML based
approach
web.xml
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Spring MVC Hello WorldApplication</display-name> <servlet> <servlet-name>HelloWorld</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/myWebAppConfigurations.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>HelloWorld</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>
We
can rewrite above web.xml file programmatically like below.
ApplicationInitializer.java
package com.sample.myApp.initializers; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRegistration; import org.springframework.web.WebApplicationInitializer; import org.springframework.web.context.support.XmlWebApplicationContext; import org.springframework.web.servlet.DispatcherServlet; public class ApplicationInitializer implements WebApplicationInitializer { public void onStartup(ServletContext servletContext) throws ServletException { XmlWebApplicationContext appContext = new XmlWebApplicationContext(); appContext.setConfigLocation("/WEB-INF/myWebAppConfigurations.xml"); ServletRegistration.Dynamic dispatcher = servletContext.addServlet("HelloWorld", new DispatcherServlet(appContext)); dispatcher.setLoadOnStartup(1); dispatcher.addMapping("/"); } }
Find
the below working application.
package com.sample.myApp.controllers; import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @Controller @RequestMapping("/hello") public class HelloWorldController { @RequestMapping(method = RequestMethod.GET) public String printHello(ModelMap model) { model.addAttribute("message", "Welcome to Spring MVC framework"); return "hello"; } }
Create
‘hello.jsp’ file under WEB-INF/jsp folder.
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Hello World Spring Web MVC</title> </head> <body> <h2>${message}</h2> </body> </html>
Create
‘myWebAppConfigurations.xml’ file under WEB-INF.
myWebAppConfigurations.xml
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <context:component-scan base-package="com.sample.myApp" /> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/jsp/" /> <property name="suffix" value=".jsp" /> </bean> </beans>
index.jsp
<html> <body> <h2>Hello World!</h2> </body> </html>
Project
structure looks like below.
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