Let’s write a Hello World application with Spring Boot. So let’s go step by step.

First we need to setup the project and create following pom.xml for maven dependencies:

<?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>com.springboot</groupId>
    <artifactId>example</artifactId>
    <version>1.0-SNAPSHOT</version>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>1.4.1.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

</project>

[addToAppearHere]

After this we need to create Application class which will run the spring boot application:

package com.springboot.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan({"com.springboot.example"})
public class Application {

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

So let’s create the Controller with the get method which will render “hello world” string as a text/plain.

package com.springboot.example;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloWorldController {

    @RequestMapping(value = "/",
            method = RequestMethod.GET)
    public ResponseEntity helloWorld() {
        return ResponseEntity.ok("Hello World");
    }
}

So it was really simple, to run the application you need to open in the browser following url:
http://localhost:8080/

In the response you have to see following:

Hello World

You can download the source codes from the github.