Spring Boot CLI

The Spring Boot CLI (Command Line Interface) is a tool that allows you to quickly develop Spring applications using Groovy scripts. This guide covers the key concepts and steps for using the Spring Boot CLI, including installation, basic commands, creating and running applications, and using CLI features.

Key Concepts of Spring Boot CLI

• CLI (Command Line Interface): A tool for developing Spring applications using command line commands and Groovy scripts.
• Groovy: A dynamic language for the Java platform used for scripting in the Spring Boot CLI.
• Spring Boot Starter: A set of convenient dependency descriptors you can include in your application to build Spring applications quickly.
• Auto-Configuration: Automatically configures your Spring application based on the dependencies you have added.

Installing Spring Boot CLI

Follow these steps to install Spring Boot CLI:

• Using SDKMAN!:

$ sdk install springboot

• Using Homebrew (for macOS):

$ brew tap pivotal/tap
$ brew install springboot

• Download the ZIP archive from the [Spring Boot website](https://spring.io/tools) and extract it.

Basic Commands

Use these basic commands to interact with the Spring Boot CLI:

• Check the version:

$ spring --version

• Run a Groovy script:

$ spring run app.groovy

• Create a new project:

$ spring init my-project

• Generate a JAR file:

$ spring jar my-app.jar app.groovy

Creating and Running Applications

Create a simple Spring Boot application using Groovy:

Example: app.groovy

@Grab('spring-boot-starter-web')
@RestController
class HelloWorld {
    @RequestMapping("/")
    String home() {
        "Hello, Spring Boot CLI!"
    }
}

Run the application:

$ spring run app.groovy

Using CLI Features

Explore some advanced features of the Spring Boot CLI:

• Dependencies: Use the @Grab annotation to include dependencies.
• Profiles: Use profiles to run the application in different environments.
• Properties: Pass properties to the application using the -- flag.

Example: Using Dependencies

@Grab('spring-boot-starter-data-jpa')
@Grab('h2')
@RestController
class Application {
    @Autowired
    PersonRepository repository

    @RequestMapping("/")
    List home() {
        repository.findAll()
    }
}

interface PersonRepository extends JpaRepository {}

@Entity
class Person {
    @Id @GeneratedValue Long id
    String name
}

Example: Using Profiles and Properties

$ spring run app.groovy --spring.profiles.active=dev --server.port=8081

Key Points

Conclusion

The Spring Boot CLI is a powerful tool for quickly developing Spring applications using Groovy scripts. By understanding and using the capabilities of the Spring Boot CLI, developers can streamline their development process and build Spring applications efficiently. Happy coding!