Spring Breezes: Spring Initializr
Spring is a set of projects dedicated to solving common problems that we face when developing enterprise applications. It supports the development of applications using JVM with Java, Kotlin, or Groovy as the main language.
One of the core components of Spring is Spring Boot. This component makes easy to create stand-alone, production-grade Spring-based applications. As mentioned on Spring Boot documentation: they take an opinionated view of the Spring platform and third-party libraries so you can get started with minimum fuss.
The "opinionated view" is another way to say convention-over-configuration. And it's safe to trust them because this opinion comes from the people behind Spring.
In other words, this is the easiest way to bootstrap a Spring-based application worrying less about dependencies, configurations, and all the other boilerplate that a JVM application usually requires.
Spring Initializr
It's already easy to simply add Spring Boot dependencies in a naked Java project to enable all the power of Spring Framework. However, the Spring team made it even easier with Spring Initializr.
With Spring Initializr you can bootstrap a Spring Boot project by simply describing:
- a build automation tool
- the main programming language
- a Spring Boot version
- the project metadata
- the complementary dependencies
It offers the possibility to generate a project using Maven or Gradle as the build automation tool. I personally prefer Gradle because it uses Groovy to define the build process and it's easier to write extensions. Feel free to evaluate both and choose the one of your preference.
As I mentioned earlier, Spring focus on the JVM. It supports Java, Kotlin, or Groovy as the main programming language. Be aware! I'll use Java! Most Spring-related concepts and architectural definitions can be applied to any of the three languages but some must be adjusted to the respective context and code style if you choose either Kotlin or Groovy.
The Spring Boot version will basically define which Spring features you'll have at your disposal. I'll use version 2.1.3 because it's the current stable version during this post writing. I don't recommend versions under 2.0 because you will miss a lot of good things.
The project metadata will be used to bootstrap the basic structure of your application, such as the base package, the main class, Java version, description, and other few things that affect your project structure.
As described by the Java package notation, companies usually use their reverse internet domain such as com.google or org.apache plus the project name. For this series I'll use com.breezes plus each post subtitle. For example, the project generated for this lesson will use com.breezes.springinitializr .
We are going to use Java 8 and the packaging will be Jar.
Spring Boot by itself offers only the minimal core capabilities required by a real application. To enable other capabilities we need to add more dependencies and Spring offers a lot of useful dependencies that solves almost every problem you will face in an enterprise context.
To keep it simple, we are going to use only the Web dependency but in future posts we'll cover other useful dependencies such as JPA and Actuator.
The Final Configuration
Finally, our final configuration without dependencies is:
The only selected dependency was Web:
By clicking on the "Generate Project" button, Spring Initiliazr will export a ZIP file with the same name defined in the project metadata.
Unzip this file and you'll have a project ready to run!
Running the project
Using the command line, enter in the unzipped folder and type./gradlew build. This command will execute all the build process and generate a build folder with the production-ready code for your application.
Note that you don't even need to install Gradle. The first time you run any ./gradlew command, it will download the required version of Gradle and put in the .gradle folder. After this, your project will use this self-contained Gradle instance to execute tasks. This is possible thanks to Gradle Wrapper.
Now run java-jar build/libs/springinitializr-0.0.1-SNAPSHOT.jar to spin up your application embedded server and make your application available at http://localhost:8080/. Be aware! If you changed the name of your application, probably you have to replacespringinitializr-0.0.1-SNAPSHOT.jar with the name of your application.
At this point, we didn't write any code, so if you try to access any URI it will display a default 404 page.
I strongly recommend that you use a version control system such as Git. By the way, Git is the default version control system that Spring uses, and your project will come with a .gitignore already.
To be continued…
In the next post, we are going to add our first "Hello World" route and its respective component and unit tests.
Feel free to check out all the code of this Spring Breeze on GitHub.
