Spring Boot

What is Spring Boot?

Open source Java framework used to create micro services but also to create easy web or stand-alone applications. It provides the next features:

  • No XML configuration is required
  • Netty (Starter Webflux) or Tomcat (Starter Web)
  • Convention over configuration
  • Easy setup
  • Very lightweight
  • Easy to test

Topics

This post shows you how to create a simple Spring Boot project with this features:

  • Gradle Build
  • Maven Build
  • Basic configuration

You can create this project from command line like this:

Using Gradle

spring init --dependencies=web --build=gradle --language=java spring-boot-setup

That command will generate a Spring project structure under spring-boot-setup folder. In order to do that you need to install SDKMAN if you are using Linux or Mac, or posh-gvm if you are using Windows. After that, you can easily set up this software development kits:

  • Spring Boot
  • Gradle
  • Maven
  • Java

Here is a build.gradle generated example.

plugins {
	id 'org.springframework.boot' version '2.3.3.RELEASE'
	id 'io.spring.dependency-management' version '1.0.10.RELEASE'
	id 'java'
}

group = 'com.jos.dem.springboot.setup'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '13'

repositories {
	mavenCentral()
}

dependencies {
	implementation 'org.springframework.boot:spring-boot-starter-web'
	testImplementation('org.springframework.boot:spring-boot-starter-test') {
		exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
	}
}

test {
	useJUnitPlatform()
}

org.springframework.boot makes it easy to stand up our Spring application with very little configuration, io.spring.dependency.management plugin provides Maven dependency managent. boot:spring-boot-starter-test is an starter for Spring Boot applications with libraries including Junit Jupiter and Mockito. This project will generate an DemoApplication.java file.

package com.jos.dem.springboot.setup;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

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

}

@SpringApplication annotation allows Spring Boot to scan recursively for beans inside this package also enables auto-configuration, attemping to guess and configure what you might need, how cool is that?. Next step, let’s create a simple rest controller as follow:

package com.jos.dem.springboot.setup;

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

@RestController
public class DemoController {

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

}

Now, in order to run it, use this command line.

gradle bootRun

Finally you can go to this address: http://localhost:8080/ and you will see our hello word message.

Using Maven

You can do the same using Maven, the only difference is that you need to specify --build=maven parameter in the spring init command line:

spring init --dependencies=web --build=maven --language=java spring-boot-setup

And when you run your project use this command:

mvn spring-boot:run

This is the pom.xml file generated:

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.3.3.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.jos.dem.springboot.setup</groupId>
	<artifactId>spring-boot-setup</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>13</java.version>
	</properties>

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

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

To browse the code go here, to download the code:

git clone git@github.com:josdem/spring-boot-setup.git

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josdem  techtalks  programming  technology  java validation  spring boot