Spring MVC hello world annotation example

In this tutorial, we will take the previous Spring MVC hello world XML-based, and convert it to a annotation-based project.

Technologies used :

• Spring 2.5.6
• JDK 1.6
• Maven 3
• Eclipse 3.6

1. Directory Structure

2. Maven

Spring’s annotation is bundled in the same spring-webmvc.jar.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
    http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mkyong.common</groupId>
    <artifactId>spring2-mvc-annotation-hello-world</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>Spring 2 MVC</name>

    <properties>
        <jdk.version>1.6</jdk.version>
        <spring.version>2.5.6</spring.version>
        <jstl.version>1.2</jstl.version>
        <servletapi.version>2.5</servletapi.version>
    </properties>

    <dependencies>

        <!-- Spring MVC framework -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- JSTL -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>${jstl.version}</version>
        </dependency>

        <!-- for compile only, your container should have this -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>${servletapi.version}</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

    <build>

      <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.3</version>
            <configuration>
                <source>${jdk.version}</source>
                <target>${jdk.version}</target>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.2.11.v20150529</version>
            <configuration>
                <scanIntervalSeconds>10</scanIntervalSeconds>
                <webApp>
                    <contextPath>/spring2</contextPath>
                </webApp>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-eclipse-plugin</artifactId>
            <version>2.9</version>
            <configuration>
                <downloadSources>true</downloadSources>
                <downloadJavadocs>true</downloadJavadocs>
                <wtpversion>2.0</wtpversion>
                <wtpContextName>spring2</wtpContextName>
            </configuration>
        </plugin>

      </plugins>

    </build>

</project>

3. Controller & Handler Mapping

Now, you can use @Controller and @RequestMapping to replace the XML configuration.

Controller – The controller class is no longer need to extend the base controller like AbstractController or SimpleFormController, just simply annotate the class with a @Controller annotation.
Handler Mapping – No more declaration for the handler mapping like BeanNameUrlHandlerMapping, ControllerClassNameHandlerMapping or SimpleUrlHandlerMapping, all are replaced with a standard @RequestMapping annotation.

HelloWorldController.java

package com.mkyong.common.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping("/welcome")
public class HelloWorldController{

    @RequestMapping(method = RequestMethod.GET)
    public ModelAndView helloWorld(){

        ModelAndView model = new ModelAndView("HelloWorldPage");
        model.addObject("msg", "hello world");

        return model;
    }
}

If the @RequestMapping is applied at the class level (can apply at method level with multi-actions controller), it required to put a RequestMethod to indicate which method to handle the mapping request.

In this case, if a URI pattern /welcome is requested, it will map to this HelloWorldController, and handle the request with helloWorld() method.

4. Spring XML Configuration

You still need to configure the view resolver and component scanning in XML file.

/WEB-INF/spring-mvc-config.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-2.5.xsd">

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

    <context:component-scan base-package="com.mkyong.common.controller" />

</beans>

5. JSP Page

A simple JSP page for demonstration.

HelloWorldPage.jsp.

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<body>
    <h1>Spring MVC Hello World Annotation Example</h1>

    <h2>${msg}</h2>
</body>
</html>

6. web.xml

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 Web MVC Application</display-name>

    <servlet>
        <servlet-name>mvc-dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-mvc-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>

</web-app>

6. Demo

6.1 To run with the embedded Jetty, type :

$ mvn jetty:run

URL : http://localhost:8080/spring2/welcome.htm

6.2 To import into Eclipse IDE.

$ mvn eclipse:eclipse

Note
If you compare this Spring MVC annotation-based hello world example with previously XML-based example, you can see that this annotation approach is easier and flexible in wiring the controller class and URL handler mapping, because you do not need to declare the controller class explicitly or extends any particular class.