Spring MVC Hello World

15/07/2012

Spring is the most popular open source java application framework as of current moment. It is one of the best job enablers too (at least in Indian software services companies).

Before starting on spring framework, I recommend you to become strong in core-java first, then remember to study servlets, jsp and then start on Spring framework.

Spring framework provides multiple modules wherein MVC and Inversion of Control container are popular among them. In this article I will present a spring MVC based Hello World web application.

I am using Spring version 3 latest available now. SpringSource provides a tool suite (STS) IDE which is based on Eclipse to develop Spring based applications. But, my personal choice for now is to continue with Eclipse JEE IDE.

Model View Controller (MVC)

Model view controller is a software architecture design pattern. It provides solution to layer an application by separating three concerns business, presentation and control flow. Model contains business logic, controller takes care of the interaction between view and model. Controller gets input from view and coverts it in preferable format for the model and passes to it. Then gets the response and forwards to view. View contains the presentation part of the application.

Spring MVC

Spring MVC is a module for enabling us to implement the MVC pattern. Following image shows the Spring’s MVC architecture

DispatcherServlet

This class is a front controller that acts as central dispatcher for HTTP web requests. Based on the handler mappings we provide in spring configuration, it routes control from view to other controllers and gets processed result back and routes it back to view.

Control Flow in Spring MVC

Based on servletmapping from web.xml request gets routed by servlet container to a front controller (DispatcherServlet).
DispatcherServlet uses handler mapping and forwards the request to matching controller.
Controller processes the request and returns ModeAndView back to front controller (DispatcherServlet). Generally controller uses a Service to perform the rules.
DispatcherServlet uses the view resolver and sends the model to view.
Response is constructed and control sent back to DispatcherServlet.
DispatcherServlet returns the response.

Spring 3 MVC Sample

Software versions used to run the sample code:

Spring 3
Java 1.6
Tomcat 7
JSTL 1.2
Eclipse Java EE IDE

Web Application Structure

Use Java EE perspective and create a new dynamic web project. Let us start with web.xml

web.xml

In web.xml primarily we are doing servlet mapping to give configuration for DispatcherServlet to load-on-startup and defining spring configuration path.

<?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"
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>Spring Hello World</display-name>
    <welcome-file-list>
        <welcome-file>/</welcome-file>
    </welcome-file-list>

    <servlet>
        <servlet-name>springDispatcher</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
      <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/spring-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springDispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

Spring Configuration

This spring configuration file provides context information to spring container. In our case,

The tag mvc:annotation-driven says that we are using annotation based configurations. context:component-scan says that the annotated components like Controller, Service are to be scanned automatically by Spring container starting from the given package.

<?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:mvc="http://www.springframework.org/schema/mvc"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        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.javapapers.spring.mvc" />
	<mvc:annotation-driven />

	<bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/view/" />
		<property name="suffix" value=".jsp" />
	</bean>

</beans>

Library files needed

commons-logging.jar
org.springframework.asm-3.1.2.RELEASE.jar
org.springframework.beans-3.1.2.RELEASE.jar
org.springframework.context-3.1.2.RELEASE.jar
org.springframework.core-3.1.2.RELEASE.jar
org.springframework.expression-3.1.2.RELEASE.jar
org.springframework.web.servlet-3.1.2.RELEASE.jar
org.springframework.web-3.1.2.RELEASE.jar
javax.servlet.jsp.jstl-1.2.1.jar (http://jstl.java.net/download.html -> JSTL Implementation)

These jars are part of standard spring framework download except the jstl.

Controller

Following controller class has got methods. First one hello maps to the url ‘/’. Annotation has made our job easier by just declaring the annotation we order Spring container to invoke this method whenever this url is called. return “hello” means this is used for selecting the view. In spring configuration we have declared InternalResourceViewResolver and have given a prefix and suffix. Based on this, the prefix and suffix is added to the returned word “hello” thus making it as “/WEB-INF/view/hello.jsp”. So on invoking of “/” the control gets forwarded to the hello.jsp. In hello.jsp we just print “Hello World”.

org.springframework.web.servlet.view.InternalResourceViewResolver

Added to printing Hello World I wanted to give you a small bonus with this sample. Just get an input from user and send a response back based on it. The second method “hi” serves that purpose in controller. It gets the user input and concatenates “Hi” to it and sets the value in model object. ‘model’ is a special hashmap passed by spring container while invoking this method. When we set a key-value pair, it becomes available in the view. We can use the key to get the value and display it in the view which is our hi.jsp. As explained above InternalResourceViewResolver is used to resole the view.

package com.javapapers.spring.mvc;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
public class HelloWorldController {

	@RequestMapping("/")
	public String hello() {
		return "hello";
	}

	@RequestMapping(value = "/hi", method = RequestMethod.GET)
	public String hi(@RequestParam("name") String name, Model model) {
		String message = "Hi " + name + "!";
		model.addAttribute("message", message);
		return "hi";
	}

}

View – Hello World

<html>
<head>
<title>Home</title>
</head>
<body>
	<h1>Hello World!</h1>

<hr/>

	<form action="hi">
		Name: <input type="text" name="name"> <input type="submit" value="Submit">
	</form>

</body>
</html>

Use key “message” in model to get the value and print it.

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
    <head>
        <title>Result</title>
    </head>
    <body>
        <h1><c:out value="${message}"></c:out></h1>
    </body>
</html>

Hello World Output

Download SpringMVC Sample Code and Run it!

Voila! I have started on Spring!

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95 comments on “Spring MVC Hello World”

Mario Guerrero said on 16/07/2012,

Hi Joe…

Thank.
Simple and great document.

Reply
Suman said on 16/07/2012,

@Suman

Its really nice.
It will really helps to the beginners and thanks for your efforts.

Reply
sanjana said on 16/07/2012,

You are one of the best teachers. Very few genuinely share their knowledge. Greatly appreciate your work.. A sincere Thank you from Samy..

Reply
Anonymous said on 16/07/2012,

nice article

Reply
Praveen Kumar Jayaram said on 16/07/2012,

Great. You started on Spring too :) Keep going.

Reply
Anonymous said on 16/07/2012,

Very Nice.. It will be good to provide the simple example for each types of controllers in spring…

Reply
nitin varshney said on 16/07/2012,

hey joy.. you always writes awesome post.. i really love to read them.

But why you jumped directly on Spring MVC. you should first start Spring Basics, DI, AOP and other topics.

I wish you will do it soon. I am really eagar to read those topics on Javapapers.com as i know you will again write something good on those topics.

Reply
vivek said on 16/07/2012,

Hello Joe,

Nice to learn Spring framework from your blog, it is easy and more understandable.
Thank you so much Joe and one more thing you told to learn servlet and jsp before starting Spring MVC, Can you please tell me what are the concepts should be known in Servlet and jsp.

Reply
Rohit said on 16/07/2012,

Hey Joe….It really help me a lot to understand the flow…and you explain it in very simply way….I have one doubt on Spring Tiles…So if it is possible then can you post the tutorial of Spring Tiles with your explanation(that is your touch)….

Thanks a lot

Reply
pankaj yadav said on 16/07/2012,

Hey Joe….It really help me a lot to understand the flow…and you explain it in very simply way….

Your way to carter things are very illustrative.

Reply