Java Developers Guide: Spring Boot Hello World Program

15 March, 2018

Spring Boot Hello World Program

Developing your first Spring Boot application is quite easy. As we know Spring Boot makes it easy to create stand-alone, production-grade Spring based Applications that you can "just run". Its basically to minimize the configuration.

In this example I have used below frameworks and tools for this example.

1. Maven 3.3.9

2. JDK 1.8

3. Eclipse IDE

4. spring-boot dependency

First step - In eclipse create a maven project "hello-world-spring-boot" as below .

Then add the dependency for spring-boot and plug-in in the pom.xml file.

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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.javadevelopersguide.www</groupId>
<artifactId>hello-world-spring-boot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<description>This is a hello world example with Spring Boot.</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.10.RELEASE</version>
</parent>
<dependencies>
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

Then create a controller class "HelloWorldController" with a rest api method sayHello()

HelloWorldController.java

package com.javadevelopersguide.springboot.example;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
/**
*
* @author manoj.bardhan
*
*/
@Controller
@EnableAutoConfiguration
public class HelloWorldController {
@RequestMapping("/hello")
@ResponseBody
public String sayHello() {
return "Hello World Developer!!!";
}
}

I have use below annotations in my controller. Here in this example the uri path is /hello

@Controller - This is used to specify the controller , as its spring framework basic.

@EnableAutoConfiguration - This enable auto configuration for Application Context.

@RequestMapping - This is used to map to spring mvc controller method.

@ResponseBody - Used to bind http response body with a domain object in return type.Its behind the scenes.

Now , my controller is ready.Just I need a luncher , who can lunch my spring boot application. I have created a "SpringBootApplicationLuncher".

SpringBootApplicationLuncher.java

package com.javadevelopersguide.springboot.example;
import org.springframework.boot.SpringApplication;
/**
* This Luncher for my spring boot application.
* @author manoj.bardhan
*
*/
public class SpringBootApplicationLuncher {
public static void main(String[] args) {
SpringApplication.run(HelloWorldController.class, args);
}
}

Now you can run this luncher to start the spring boot application.Then, you can see the below screenshot showing the tomcat is started. As you know spring-boot is embedded with tomcat feature.