Getting Started with Spring MVC

The OLD XML Configuration

pom.xml. The jstl and servlet-api is only need if you use JSTL in your JSP pages.

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>se.magnuskkarlsson.examples</groupId>
    <artifactId>example-springmvc-xml</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.build.outputEncoding>UTF-8</project.build.outputEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <failOnMissingWebXml>false</failOnMissingWebXml>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- embedded Jetty server, for testing -->
            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.2.11.v20150529</version>
                <configuration>
                    <scanIntervalSeconds>10</scanIntervalSeconds>
                    <webApp>
                        <contextPath>/</contextPath>
                    </webApp>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

web.xml. The old school, but is good to know, since there are several old references to the XML way.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    version="3.1">

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/application-context.xml</param-value>
    </context-param>

    <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value></param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

/WEB-INF/spring/application-context.xmlIn Spring you can split the Spring XML configuration into several files, but I tend to think that using several configuration files, will only make you wander lost in configuration, so I prefer one configuration file.

<?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: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.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="se.magnuskkarlsson.example.springmvc.controller" />

    <mvc:annotation-driven />

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

Now the actual "app". Spring MVC design is much like Struts with one Servlet that dispatch request. HelloController

package se.magnuskkarlsson.example.springmvc.controller;

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 HelloController {

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String hello(@RequestParam(value = "name", required = false, defaultValue = "World") String name,
            Model model) {

        model.addAttribute("name", name);
        return "hello";
    }
}

And your app view - WEB-INF/view/hello.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello Spring MVC</title>
</head>
<body>
    <h2>Hello Java ${name}!</h2>
</body>
</html>

And finally lets test it by running 'mvn jetty:run' and open http://localhost:8080/hello?name=foo.

$ mvn clean install; mvn jetty:run

The NEW Java Configuration

Now we delete web.xml and /WEB-INF/spring/application-context.xml. And manually write code that do the same thing.

package se.magnuskkarlsson.example.springmvc;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.context.support.GenericWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

public class MainWebAppInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext container) throws ServletException {
        // Create the 'root' Spring application context
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.scan("se.magnuskkarlsson");

        // Manage the lifecycle of the root application context
        container.addListener(new ContextLoaderListener(rootContext));

        // Register and map the dispatcher servlet
        ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher",
                new DispatcherServlet(new GenericWebApplicationContext()));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/");
    }
}

package se.magnuskkarlsson.example.springmvc;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@EnableWebMvc
@Configuration
@ComponentScan(basePackages = { "se.magnuskkarlsson.example.springmvc.controller" })
public class AppConfig implements WebMvcConfigurer {

    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver bean = new InternalResourceViewResolver();
        bean.setPrefix("/WEB-INF/view/");
        bean.setSuffix(".jsp");
        return bean;
    }
}