This blog presents instructions on how to quickly get started with Spring Boot Hello World with just one Java file and a Pom.xml.

Before getting to the files, make sure you have installed and configured the following:

• Java: Set up Java_Home, as it is required by Maven.
• Maven: Maven would be used to package our app.

Java Code Sample

Below is the code for the Java file. Make sure to create hello/HelloController.java file within src/main/java. This is required for Maven to package it correctly.

package hello;

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.web.bind.annotation.*;

@RestController
@SpringBootApplication
public class HelloController {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

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

}

Pom.xml Code Sample

The following is the code for the Pom.xml file. Make sure to put Pom.xml at the topmost level (alongside the src folder):

<?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>hello</groupId>
    <artifactId>SpringBootSampleWeb</artifactId>
    <version>0.0.1</version>
<properties>
    <!-- The main class to start by executing java -jar -->
    <start-class>hello.HelloController</start-class>
</properties>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.0.RELEASE</version>
    </parent>

    <!-- Additional lines to be added here... -->
    <dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>
</project>

Package and Run the App

Once you have created the file, execute the following command to run the code:

mvn package 
java -jar target/SpringBootSampleWeb-0.0.1.jar