Spring Initializr - Bootstrap Your Spring Boot Applications at F1 speed!

Spring Initializr http://start.spring.io/ is great tool to bootstrap your Spring Boot projects.

It allows you to create varied range of Spring Boot based Applications from a very simple UI. Some of the types of applications you can bootstrap are:

Web Applications
Restful Applications
Batch Applications

Spring Boot provides a wide range of starter projects. Spring Initializr supports all of them and more. Among a varied range of starter projects and options supported are:

spring-boot-starter-web-services : For building applications exposing SOAP Web Services
spring-boot-starter-web - Build Web applications & RESTful applications
spring-boot-starter-test - Write great Unit and Integration Tests
spring-boot-starter-jdbc - Traditional JDBC Applications
spring-boot-starter-hateoas - Make your services more RESTful by adding HATEOAS features
spring-boot-starter-security - Authentication and Authorization using Spring Security
spring-boot-starter-data-jpa - Spring Data JPA with Hibernate
spring-boot-starter-cache - Enabling Spring Framework’s caching support
spring-boot-starter-data-rest - Expose Simple REST Services using Spring Data REST

In this guide, lets consider creating a simple web application with Spring Initializr.

Bootstrapping a Web application with Spring Initializr

Creating a Web application with Spring Initializr is very simple.

As shown in the image above, following steps have to be done

Launch Spring Initializr http://start.spring.io/ and choose the following
- Choose com.in28minutes.springboot as Group
- Choose student-services as Artifact
- Choose the following dependencies
  - Web - Actuator - DevTools
Click Generate Project button at the bottom of the page.
Import the project into Eclipse or IntelliJ

Structure of the project created

Screenshot shows the project structure of the imported maven project.

StudentServicesApplication.java - Spring Boot Launcher. Initializes Spring Boot Auto Configuration and Spring Application Context.
application.properties - Application Configuration file.
StudentServicesApplicationTests.java - Simple launcher for use in unit tests.
pom.xml - Included dependencies for Spring Boot Starter Web, Actuator, DevTools. Uses Spring Boot Starter Parent as parent pom.

Complete Code Generated

Lets look at each of the file that is generated

/pom.xml

Three important things that are configured in pom.xml.

Spring Boot Parent Pom - You can read more about Spring Boot Starter Parent here - http://www.springboottutorial.com/spring-boot-starter-parent.
Spring Boot Starter Web - You can read more about Spring Boot Starter Web here - http://www.springboottutorial.com/spring-boot-starter-projects.
Spring Boot Starter Plugin

<?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.in28minutes.springboot</groupId>
	<artifactId>student-services-initializr</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>student-services</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.0.0-M3</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<java.version>17</java.version>
	</properties>

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

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

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

	<repositories>
    <repository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
  </repositories>
  <pluginRepositories>
    <pluginRepository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </pluginRepository>
  </pluginRepositories>


</project>

/src/main/java/com/in28minutes/springboot/StudentServicesApplication.java

@SpringBootApplication - Initializes Spring Boot Auto Configuration and Spring application context. Read more about Auto Configuration here - http://www.springboottutorial.com/spring-boot-auto-configuration.
SpringApplication.run - Static method to launch a Spring Boot Application.

package com.in28minutes.springboot.studentservices;

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

@SpringBootApplication
public class StudentServicesApplication {

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

/src/main/resources/application.properties

/src/test/java/com/in28minutes/springboot/StudentServicesApplicationTests.java

Integration test launches the complete Spring Boot Application. Read more about integration tests here - http://www.springboottutorial.com/integration-testing-for-spring-boot-rest-services.

package com.in28minutes.springboot.studentservices;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit.jupiter.SpringExtension;

@ExtendWith(SpringExtension.class)
@SpringBootTest
public class StudentServicesApplicationTests {

  @Test
  public void contextLoads() {}
}

Running the application

Following log is generate when you run StudentServicesApplication.java as a Java Application.

    .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::             (v3.0.0-M3)

2022-07-09T07:31:11.653+05:30  INFO 6649 --- [  restartedMain] c.i.s.s.StudentServicesApplication       : Starting StudentServicesApplication using Java 17.0.2 on Puneeths-MacBook-Pro.local with PID 6649 (/Users/puneethsai/devworkspace/student-services/target/classes started by puneethsai in /Users/puneethsai/devworkspace/student-services)
2022-07-09T07:31:11.657+05:30  INFO 6649 --- [  restartedMain] c.i.s.s.StudentServicesApplication       : No active profile set, falling back to 1 default profile: "default"
2022-07-09T07:31:11.718+05:30  INFO 6649 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2022-07-09T07:31:11.718+05:30  INFO 6649 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2022-07-09T07:31:13.249+05:30  INFO 6649 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2022-07-09T07:31:13.263+05:30  INFO 6649 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2022-07-09T07:31:13.263+05:30  INFO 6649 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/10.0.21]
2022-07-09T07:31:13.326+05:30  INFO 6649 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2022-07-09T07:31:13.329+05:30  INFO 6649 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1607 ms
2022-07-09T07:31:13.977+05:30  INFO 6649 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2022-07-09T07:31:13.984+05:30  INFO 6649 --- [  restartedMain] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 1 endpoint(s) beneath base path '/actuator'
2022-07-09T07:31:14.031+05:30  INFO 6649 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2022-07-09T07:31:14.045+05:30  INFO 6649 --- [  restartedMain] c.i.s.s.StudentServicesApplication       : Started StudentServicesApplication in 3.168 seconds (process running for 4.02