Creating First Spring Boot Application

There are several ways we can bootstrap a Spring Boot project: 1. Using Spring Initializr 2. Using the Spring Boot CLI 3. From IntelliJ IDE

Create Spring Boot Project using Spring Initializr

Spring Initializr is a web-based tool that helps you configure and generate the Spring boot project template. To bootstrap a Spring Boot project using Spring Initializr, visit https://start.spring.io.

Let us now configure our Spring boot project:

• Project Type: Select the Maven or Gradle build type and select the language. Let’s select Gradle with Java.
• Language: You can write Spring Boot code using Java, Kotlin, or Groovy. We will use Java throughout this course.
• Spring Boot Version: Select the Spring Boot version out of all available versions. At the time of creating this video Spring Boot 3.2.0 is the latest release version. Let’s select that

Let us now configure our Spring Boot project:

• Project Type: Select either the Maven or Gradle build type and choose the programming language of your choice.
• Language: Spring Boot code can be written in Java, Kotlin, or Groovy. In this course, we will use Java exclusively.
• Spring Boot Version: Choose the Spring Boot version from the available options. Currently, the latest Spring Boot release version is 3.3.4.

Now, provide the basic project details like the group, artefact, and name of your project.

• Group: Usually the reverse of your domain. If your domain is stacktips.com, your group name will be com.stacktips
• Artifact Id: The artifact name is the name of the jar without a version. For example, if your artifact name is hello-spring, then the jar will be hello-spring-[version].jar.
• App Name: Provide a name for your application. Let’s call it a hello-spring.
• Description: You may additionally describe your project.
• Package name: This is the base package name for your project. Let’s use com.stacktips.app as our package name.
• Package type: We have two choices for the package type, Jar and WAR. Both JAR (Java Archive) and WAR (Web Archive) are formats used in the Java ecosystem for packaging and distributing applications. But they have a completely different purpose.

We will build a self-contained Spring boot application, so let's select Jar for the package type.

• Java Version: Spring Boot 3 requires a minimum of Java 17.
• Select Starter Dependencies: Now, select the Add Dependency button to choose the Spring boot starter dependencies for your project. Let us choose Spring Boot Starter Web and Spring Boot Actuator.
• Explore and Generate: Explore button allows you to review the project structure beforehand. Once everything is okay, you can click on the Generate button.

This will download the new Spring Boot project as a zip file. Now, extract the zip file and open the project in your IntelliJ IDEA.

Creating Spring Boot Project using Spring CLI

The Spring Boot CLI (Command Line Interface) offers an alternative method for bootstrapping a Spring Boot project. With CLI, we can configure everything that Spring Initializr provides directly through the command line.

Before we begin using the Spring Boot CLI, we must ensure that it is installed. To verify the installation of the Spring Boot CLI, simply enter the following command:

spring --version

If it is installed, you will see the Spring Boot version printed as follows;

Spring CLI v3.2.0

If it is not installed, there are several ways we can install the Spring CLI. We can install using SDKMAN, OSX Homebrew, MacPorts, or using manual installation methods.

In this article, we will install using SDKMAN, but if you prefer other installation methods, then you may refer to the official Spring CLI installation guide

Install Spring Boot CLI using SDKMAN

Before we install, let us first get the list of available Spring Boot releases using the following command.

sdk ls springboot

It will print all the list of available Spring Boot releases.

To install Spring Boot CLI enter the following command;

sdk install springboot

Once Spring Boot CLI is installed, You can list the capabilities of the service by using the --list flag:

spring init --list

Once Spring CLI is installed, we can continue creating the Spring Boot project. To create a Boot project from the command line use the following command;

spring init --type=gradle-project
     --java-version=17
     --language=java
     --name=hello-spring
     --artifact-id=hello-spring
     --group-id=com.stacktips
     --packaging=jar
     --dependencies=web,actuator
     hello-spring

It will create a new Spring Boot project with all the folders and files similar to the Spring Initializr inside the hello-spring directory.

You do not need to use the Spring CLI to work with Spring Boot, but it is a quick way to get a Spring application off the ground without using Spring Initializr.

Creating Spring Boot Project Using IntelliJ IDE

You can also create a Spring Boot project from IntelliJ, but for that, you will need the IntelliJ Ultimate edition, which requires a commercial license.

• To create a new Spring Boot project from the IntelliJ Ultimate edition, click File | New | Project.
• This will open the new project dialog, and the Spring Initializr generator can be found in the left side pane.

From there on, all the configurations are similar to the Spring Initializr and Spring CLI.

Build and Run Spring Boot Project

Before we build and run our code, let us first open the IntelliJ IDE and import the project we have created. To import the project:

1. Go to File | Open.
2. Browse the downloaded folder and click on the Open button.

When the project is loaded for the very first time in your IDE, it may take a while as it has to download all the direct and transitive dependencies for your project. The load time will be based on your internet speed.

There are several different ways we can build and run a Spring Boot project. Some of the most common methods are:

• Running from IDE
• Using Gradle or Maven build tools
• Run as a Fat JAR

Running from an IDE

Running a Spring Boot project from an IDE is the most straightforward approach. Each IDE provides features that enable developers to build and execute the Spring Boot application with just a single click.

To get started, open the HelloSpringApplication class, which contains the main() method (typically marked with the @SpringBootApplication annotation). Then, click in the gutter and choose the Play option to run the spring boot application.

Build and Run using Gradle Command

To run the application from the command line, follow these two steps: first, build the project, and then Run it. For Gradle projects, you can build the project using the following command:

./gradlew build

Now, you can run the app using the bootRun gradle command.

./gradlew bootRun

Build and Run using Maven Command

For Maven projects, you can build the Spring boot project using the following command:

./mvnw clean package

To run the app use the spring-boot:run gradle command.

./mvnw spring-boot:run

Running Application as a FatJar

To run the application as a FatJar we first need to package the Spring Boot application into an executable JAR file.

To generate a JAR file we can use the following Maven command:

./mvnw clean package

To generate a JAR file we can use the following Gradle command:

./gradlew clean build

Once the JAR is generated, we can run the fat JAR using the java -jar command.

java -jar build/libs/hello-spring-0.0.1-SNAPSHOT.jar

When you run your Spring Boot application, you will see a log message like this: ![[3.5. running-spring-boot-as-fat-jar.png]]

Notice that we are using mvnw and gradlew wrapper utilities to build and package our Spring boot application. We will learn more about them in the next chapter.