Spring 4 Framework introduced with lots of improvements and features. Here we are going to deal with developing web application using Spring 4 Framework.

Project Requirements

1. Spring 4.0.1.RELEASE jars
   
2. JDK 1.6
3. JSTL 1.2.jar
4. Eclipse Java EE IDE(Eclipse JUNO)

Project Setup

Spring Configuration

Spring MVC 4 has replaced XML configuration with Java file configuration. You can use either one of them to build web application.

1.Configuring Spring Beans(spring-servlet.xml)

Spring MVC 4 facilitates by providing following annotations to define spring beans.

1. @Configuration: It marks the file configuration file.
2. @ComponentScan :It is used to scan the service classes.
3. @EnableWebMvc : It is equivalent to which enables Web MVC environment.

AppConfig.java

The @Bean annotation is used to define spring beans here ViewResolver is annotated using @Bean annotation.

package com.expertwebindia.services;
import java.util.List;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
@Configuration
@ComponentScan(basePackages = {"com.expertwebindia.controllers"})
@EnableWebMvc
public class AppConfig {
@Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/views/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}

}

The above configuration is same as below spring-servlet.xml.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
<context:component-scan base-package="com.expertwebindia.controllers"/>
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>

2.Configuring Dispatcher Servlet

As in Spring 3 we need to configure Dispatcher Servlet in web.xml. Now in Servlet 3.0 we can add servlet entry without web.xml.

WebAppInitializer.java

package com.expertwebindia;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration.Dynamic;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
public class WebAppInitializer implements WebApplicationInitializer {
public void onStartup(ServletContext servletContext) throws ServletException {
AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
ctx.register(AppConfig.class);
ctx.setServletContext(servletContext);
Dynamic dynamic = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));
dynamic.addMapping("/");
dynamic.setLoadOnStartup(1);
}
}

The below configuration is equivalent to above Java file configuration which are doing in web.xml.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>spring</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>

3.Defining Spring Controller

Defining controller is same as Spring 3, using @Controller annotation.

HelloWorldController.java

package com.expertwebindia.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class HelloWorldController {
@RequestMapping(value="/hello")
public String hello(ModelMap model){
model.addAttribute("msg","Hello World Example by Expertwebindia");
return "hello";
}

}

4.Defining Views(JSP files)

Here is one view used which hello.jsp.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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>Spring Web MVC 4 Example</title>
</head>
<body>
<h1>${msg}</h1>
</body>
</html>

Download Source Code

You need to put Spring 4 Jars in WEB-INF/lib.

Run Application

http://localhost:8080/SpringMVC4/hello