Spring boot MVC application tutorial

21 06 2014

spring-logoI will tutor you to create simple Spring MVC application based on Spring boot. App will have two linked web pages with thymeleaf. The project itself will be made in Eclipse as an Gradle project. Let’s start!

Download Source Code

Source for this tutorial is available here, on GitHub

Create project with Gradle build file

Create build.gradle file. First of all depict repositories and dependencies that you will use for gradle plugins:

buildscript {
    repositories {
        maven { url "http://repo.spring.io/libs-release" }
        mavenLocal()
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.1.1.RELEASE")
    }
}

Then apply plugins for java, spring-boot and eclipse to have default targets of these plugins:

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'spring-boot'

Now show which java version compliance you want to have, and how your jar file will be named:

sourceCompatibility = 1.6

jar {
    baseName = 'looksok-mvc-demo'
    version =  '0.1.0'
}

And add repositories with dependencies used in your code:

repositories {
    mavenLocal()
    mavenCentral()
    maven { url "http://repo.spring.io/libs-release" }
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-thymeleaf")
    testCompile("junit:junit")
}

Note: Use gradle version 1.1 or higher

Create web page templates in thymeleaf

Start with welcome page in src/main/resources/templates/hello.html with link to greeting page. If gradle did not automatically create directory structure, then create necessary folders on your own.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" 
	xmlns:th="http://www.thymeleaf.org" >
    <head>
        <title>Spring MVC Example</title>
    </head>
    <body>
        <h1>Welcome!</h1>

        <p>Click <a th:href="@{/greeting}">here</a> to advance to the next page.</p>
    </body>
</html>

and second template named greeting.html with link to previous page:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" 
	xmlns:th="http://www.thymeleaf.org" >
    <head>
        <title>Spring MVC Example</title>
    </head>
    <body>
        <h1>Hello on a second page!</h1>

        <p>Click <a th:href="@{/hello}">here</a> to go back.</p>
    </body>
</html>

Configure MVC application components

Now with template pages you need to register controllers that will expose views (templates). Create java class with MVC Configuration (extending WebMvcConfigurerAdapter and market with @Configuration annotation). There override the addViewControllers method and add your views to the registry:

@Configuration
public class MvcConfig extends WebMvcAutoConfigurationAdapter {

	@Override
	public void addViewControllers(ViewControllerRegistry registry) {
		registry.addViewController("/hello").setViewName("hello");
		registry.addViewController("/greeting").setViewName("greeting");
	}
}

Make the Spring boot application executable
Spring boot will compile to Uber jar file with servlet engine embedded. To make it possible, the jar needs to have main class. This is how it should look like:

@EnableAutoConfiguration
@Configuration
@ComponentScan("pl.looksok.spring")
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}
}

Remember about annotations. The configuration annotation to indicate this is Spring config class, EnableAutoConfiguration of servlet engine and ComponentScan with package to scan (package is not mandatory when all @Configuration classes are in the same package).

Compile and run
Execute the command to build spring boot app:

gradle build compile

and to start the application:

java -jar [path_to_your_otput_jar]/looksok-mvc-demo-0.1.0.jar

To launch webpage, access the url:
localhost:8080\hello

Download Source Code

Source for this tutorial is available here, on GitHub

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