Java Developers Guide: spring

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.