Spring Boot Starter

Starters

A meta-dependency (메타 의존성) that bundles together a prescriptive set of dependencies needed to implement a specific feature

• Gradle Dependency Configuration, also look at the advantages of using gradle
• What is dependency (+ Dependency in Gradle)

• 🐣Spring & SpringBoot
• When you add a single starter, it automatically includes all the related libraries and default configurations associated with that particular functionality
• Example: spring-boot-starter-web
  • ⭐Spring MVC
  • Jackson (JSON 직렬화)
    • A library for our convenience, has ObjectMapper class
      • Conversion between ☕Java objects and JSON
    • Related to broader concept: Java Serialization (and persistence)
  • Embedded Tomcat
  • Logging (SLF4J + Logback)
• Spring Boot starters are a feature that maximizes the advantages of using gradle.
  • ALSO READ: Gradle - BOM (Bill of Materials) Management
  • All starters rely on BOM

Maven Central

Website to explore Spring Boot Starter dependencies in a Gradle environment Maven Central

• Overview
  • Contents Included:
    • Group ID / Artifact ID
    • Latest version information
    • License
    • Metadata such as release date and tags
  • How to Use It:
    • When you want to quickly understand the purpose of this library.
    • When you need a summarized view of an unfamiliar artifact’s information.
• Versions
  • lists all available versions of an artifact.
  • Contents Included:
    • Version number
    • Release date
    • Each version is clickable, leading to its detailed information page.
  • How to Use It:
    • To see what versions of the artifact exist.
    • To help decide which version to use, whether you need a stable release or the latest one.
• Dependents
  • List of Projects that uses the current artifact as dependencies
  • “Who depends on me?”
  • U can gauge the popularity or adoption of a library.
• Dependencies
  • List of projects that the current artifact uses as dependencies
  • Includes transitive dependencies (both direct and indirect dependencies are shown).
  • “Who do I depend on?”
  • You can use it to understand the internal composition of a library, including its underlying components.

Most used starters

There are a LOT (50+), but these are the most used.

Starter Name	Description
spring-boot-starter	The minimal common starter, including basic logging (SLF4J + Logback).
spring-boot-starter-web	For developing Spring MVC-based web applications. (more below) - already includes spring-boot-starter
spring-boot-starter-data-jpa	Integrates Spring Data JPA with Hibernate for data access.
spring-boot-starter-security	Provides Spring Security functionalities for authentication and authorization.
spring-boot-starter-test	A comprehensive starter for testing, including JUnit, Mockito, and AssertJ.
spring-boot-starter-thymeleaf	Integrates the Thymeleaf template engine for server-side HTML rendering.
spring-boot-starter-validation	Integrates the Bean Validation API (typically with Hibernate Validator) for data validation. - Includes validation for Bean
spring-boot-starter-logging	Provides default logging based on SLF4J and Logback. (Often included by other starters like web).
spring-boot-starter-actuator	Exposes operational metrics and monitoring APIs for your application.

• You typically combine starters based on your application’s structure and role. For example:
  • REST API Server: You’d likely use starters like web, data-jpa, validation, and actuator.
  • Admin Dashboard: You might opt for thymeleaf, security, and web starters.
• Starters sit at the top of the Gradle dependency tree, and often include other starters or libraries under the hood.
  • Use ./gradlew dependencies to:
    • Visualize the full dependency graph.
    • See which libraries are pulled in.
  • Understand starter hierarchy.

More about spring-boot-starter-web

Main Included Dependencies

Dependency	Description
spring-web	Core features of the ⭐Spring MVC
spring-webmvc	Provides components like DispatcherServlet, Controller, View, etc.
jackson-databind	Supports JSON serialization/deserialization
validation-api, hibernate-validator	Supports Bean Validation (e.g., @Valid)
spring-boot-starter-tomcat	Runs the application with an embedded Tomcat server - Spring Servlet

The Auto-Configuration Logic

• Once the starter brings in all those “ingredients,” the spring-boot-autoconfigure library kicks in (which is automatically brought in by starters). It looks at the libraries you have available (on your “classpath”) and uses conditional logic to set everything up.
• It essentially follows a recipe like this:
  • “IF spring-webmvc is present, THEN I will automatically set up a DispatcherServlet and everything needed to make it work.”
  • “IF jackson-databind is present, THEN I will automatically set up the MappingJackson2HttpMessageConverter to handle JSON.”
  • “IF an embedded server like tomcat is present, THEN I will start it up and configure it to run the application.”