Creating First Spring Boot Application

Before we begin, we need the following prerequisites for developing Spring Boot applications.

• Java 17 or 21
• IDE (Integrated Development Environment):

Java 17 or 21

The current stable version of the Spring boot framework is 3.2.0, and it requires Java17 and is compatible up to and including Java 21.

Check if you have Java installed using the following command.

java --version

If Java is not installed, you can follow the installation process from my blog post How to Install Java for MacOS and Windows?

IDE (Integrated Development Environment):

An Integrated Development Environment (IDE) is a tool that helps to streamline the coding, debugging, and project management for developers. It offers features like code editing, refactoring, debugging, integrated terminal, and many other features to support application development.

• VSCode - Free
• Eclipse - Free
• IntelliJ IDEA Community (Free) or IntelliJ Ultimate (Licensed)

I prefer IntelliJ IDEA, as it is one of the most advanced and preferred IDEs for Java developers. If you haven’t installed it already, you can install the community edition of IntelliJ here https://www.jetbrains.com/idea/download/

Choosing build tools Maven vs. Gradle

Build tools play a crucial role in software development. Build tools are used to automate the process of compiling, testing, packaging, and deploying your application. This can save you a lot of time, especially when working with a large, distributed team.

Using build tools you can also simplify the process of managing dependencies for your project. It helps to automate the process of resolving and including external libraries in your project.

Primarily there are two popular build tool choices for Spring Boot:

• Maven
• Gradle

Maven:

Maven is a popular build automation tool used primarily for Java projects. It uses an XML file called a  pom.xml (Project Object Model) to define the project's configuration.

The pom.xml file serves as the central configuration file for a Maven project. It contains information about the project, including its dependencies, plugins, build lifecycle, and other relevant details.

Gradle

Gradle is another build automation tool that uses either Groovy or Kotlin DSL (Domain-Specific Language) for defining build scripts. Gradle maintains the dependency configurations in build.gradlefile and it is typically stored in the project's root directory.

An example of a Gradle build file for a Spring Boot application follows.

Choosing Between Maven and Gradle

The choice between Maven and Gradle for Spring Boot development depends on your personal preferences and the specific needs of your project.

While Maven is more mature and almost like an established standard in the Java community, Gradle is a more modern build system and has gained popularity recently. Both Gradle and Maven are very powerful and good fit for larger and more complex projects.

Create a New Spring Boot Project

There are a few convenient options available for bootstrapping your Spring Boot project template.

1. Using Spring Initializr

2. Using the Spring Boot CLI

3. Using IntelliJ

Using Spring Initializer

Spring initializer is a web-based tool that helps you to configure and generate the Spring boot project template. Let us use the Spring initializer to create a new Spring Boot project.

First, visit https://start.spring.io in your browser to open Spring initializer.

Let us now configure our 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

Now, provide the basic project details like the group, artifact, 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 movies-api, then the jar will be movies-api-[version].jar.
• App Name: Provide a name for your application. Let’s call it a movies-api-app.
• 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. Let us select Jar

• Java Version: Spring boot 3.2.0 require minimum of Java 17 and it is compatible up to Java 21. I have Java 21 installed in my system, so I have selected Java 21, but you can very well choose Java 17.
• Select Starter Dependencies: On the right-hand side, you will notice the Add dependency button. Clicking on the Add dependencybutton will allow you to choose the Spring boot starter dependencies for your project. Let us for now choose Spring Boot Starter Web and Spring Boot Actuator for this example.
• Explore and Generate: Once all details are filled in, you can click on the Explore button to see the project structure beforehand. Once you’ve verified your configurations, you can click on Generate button.

This will download a new Spring Boot project with the configuration you’ve selected. Now, you can 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) is a command line tool that can be used to generate the spring boot project. Everything you can do with the Spring initializer can be configurable though Spring Boot CLI.

Before we work the Spring Boot CLI we need to ensure the CLI is installed and available for us to use. To check if the Spring Boot CLI is installed, type 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 is 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. The scope of this chapter covers the installation using SDKMAN, but if you prefer other installation methods, then you may refer the official installation guide.

Installing the Spring Boot CLI

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,

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

Now to Create the Spring Boot project, we can use the followinng command;

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

This command will create a Spring Boot project inside the movies-api-app directory. All the folders and files created is similar to the one we have created using the Spring Initilizer.

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 Initilizer.

Using IntelliJ

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.

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. And browse the downloaded folder and click on Open button.
your IDE, then it may take a while as it has to download all the direct and transitive dependencies as configured 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 Far JAR

Running from an IDE

This is the simplest way to run a Spring Boot project. Every IDE is equipped with options that allow developers to build and run the spring boot application in a single click.

Open the MoviesApiApplication class with the main() method (it is usually also designated with the @SpringBootApplication annotation), click  in the gutter, and select to run the class.

Build and Run using Gradle Command

For Gradle projects, you can build the Spring boot project to into an executable Jar using the following command:

./gradlew build

Start/Run spring boot application

./gradlew bootRun

Build and Run using Maven Command

For Maven projects, you can build the Spring boot project to into an executable Jar using the following command:

./mvnw clean package

Start/Run spring boot application

./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. For that, we can use a build tool like Maven or Gradle.

Maven:

./mvnw clean package

Gradle:

./gradlew clean build

Once the jar files are built, we can run the application as a fat jar using the java -jar command.

java -jar build/libs/movies-api-0.0.1-SNAPSHOT.jar

When you run your Spring Boot application, you will see a log message like this:

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.