Spring Boot Starters

追加: 2026-06-01

[00:00:00]Hi everyone. Welcome back. In this lecture, let's take a look at one of the most useful features of Spring Boot, the Spring Boot Starters.

[00:00:09]Before we understand what starters are, let's first look at the problem that they were designed to solve.

[00:00:15]Well, before Spring Boot existed, if we wanted to create a Spring MVC application, we had to manually add a lot of dependencies. Things like Spring Web MVC, Jackson for JSON, a servlet API, and a web server dependency such as Tomcat. And then, we had to carefully manage compatible versions for all of these.

[00:00:39]Let's say you also wanted to use Hibernate with Spring Data JPA. Again, you had to add each dependency, Hibernate Core, JPA API, Spring ORM, and make sure their versions worked perfectly together.

[00:00:55]And if you decided to secure your application with Spring Security, you would have to repeat the process, adding multiple security-related dependencies, and maintaining compatible versions.

[00:01:08]So, maintaining all of these frameworks and version alignments was painful.

[00:01:12]It often led to class path conflicts and no such method error issues during runtime.

[00:01:20]This is where Spring Boot Starters came in to solve that problem.

[00:01:25]Spring Boot Starters are pre-configured dependency descriptors that bundle commonly used libraries for a particular functionality with the correct versions already managed for you.

[00:01:36]In simple terms, a starter is just a single dependency that automatically pulls in all the other libraries you need to get started with a specific feature.

[00:01:46]For example, if you want to build a web MVC application, you no longer need to add a dozen different dependencies manually. You can just add one dependency, the Spring Boot Starter Web MVC.

[00:02:00]Starting from Spring Boot 4, the traditional Spring Boot Starter Web dependency has been renamed to Spring Boot Starter Web MVC.

[00:02:09]This single starter dependency internally brings in Spring MVC, Jackson for JSON, the embedded Tomcat server, and the HTTP converter module, all with compatible versions.

[00:02:21]That means just by adding this one dependency, you automatically get everything you need to build a fully functional Spring MVC web application.

[00:02:30]Let's take another example, the Spring Boot Starter Data JPA dependency.

[00:02:36]When you add this starter, it automatically includes all the libraries required for working with a relational databases, Hibernate ORM, Spring Data JPA, the Jakarta Persistence API, and JDBC support, all pre-configured and version managed.

[00:02:54]This means you don't have to worry about which version of Hibernate works with which version of Spring Data JPA. Spring Boot takes care of that internally.

[00:03:04]Now, let's say you want to add security.

[00:03:06]In that case, you just include the Spring Boot Starter Security dependency.

[00:03:12]This single dependency automatically includes all the Spring Security modules you need, such as core, web security, configuration support, and cryptography libraries. All of these come from the same compatible version family.

[00:03:27]Similarly, for testing, we have the Spring Boot Starter Test dependency.

[00:03:33]This starter includes JUnit 5, Mockito, Hamcrest, AssertJ, JSON Path, and other popular testing frameworks. So, you don't have to add or manage them manually.

[00:03:46]Now, behind the scenes, all of these starters rely on the Spring Boot Dependencies BOM. That's the bill of materials file, which manages all the versions of these dependencies for you.

[00:03:57]So, when you add a starter dependency, Spring Boot automatically aligns the correct versions of every library based on what's defined in the Spring Boot BOM.

[00:04:09]This ensures consistent, stable builds and prevents version conflicts between frameworks like Spring, Hibernate, and Jackson.

[00:04:18]There are many other starter dependencies that come with Spring Boot.

[00:04:22]Let's look at some of the most popular ones.

[00:04:26]For building web MVC applications, Spring Boot Starter Web MVC.

[00:04:32]For working with JPA and Hibernate, Spring Boot Starter Data JPA.

[00:04:38]For securing your apps, Spring Boot Starter Security.

[00:04:42]For building restful microservices that expose or consume in JSON, you can use the Spring Boot Starter Web MVC, which already includes Jackson.

[00:04:53]For reactive applications, Spring Boot Starter WebFlux.

[00:04:57]For Thymeleaf-based web UI applications, Spring Boot Starter Thymeleaf.

[00:05:03]For testing, Spring Boot Starter Test.

[00:05:07]And for logging, Spring Boot automatically includes the Spring Boot Starter Logging, which brings in Logback and SLF4j as the default logging framework.

[00:05:18]So, you can see the idea behind all these starters is to help developers get started quickly without having to manually add or manage multiple library versions. Now, let's see one complete example in an action. Let's go to IntelliJ IDEA and open the pom.xml file.

[00:05:38]Inside the dependency section, you will see something like this. Group ID org.springframework.boot and artifact ID Spring Boot Starter Web MVC.

[00:05:51]Now, this single dependency automatically brings all the required libraries to build a web application and restful web services.

[00:06:00]Let's take a quick look at what this dependency includes internally.

[00:06:04]If you open Spring Boot Starter Web MVC dependency, it internally provides the following dependencies: Spring Boot Starter, Spring Boot Starter Jackson, Spring Boot Starter Tomcat, Spring Boot HTTP Converter, and Spring Boot Web MVC.

[00:06:27]And if you go one level deeper, the Spring Boot Web MVC module itself includes Spring Web and Spring Web MVC from the core Spring Framework 7, as well as servlet and converter dependencies.

[00:06:40]So, in short, when you add just one dependency, Spring Boot Starter Web MVC, Spring Boot automatically brings everything you need for building REST API and MVC-based web applications.

[00:06:54]You don't have to manually configure Tomcat, Jackson, or servlet mappings.

[00:06:59]Everything is auto-configured behind the scenes.

[00:07:03]Let's understand how this helps.

[00:07:05]When your application starts, Spring Boot's auto-configuration system automatically configures a dispatcher servlet, a default embedded Tomcat server, and a JSON message converter using Jackson.

[00:07:19]So, you can directly focus on writing your REST controllers and business logic instead of worrying about configuration or dependency management.

[00:07:28]Each starter internally manages all the necessary dependencies and versions for you. You just declare one dependency, and Spring Boot takes care of the rest.

[00:07:40]That's the power of the SpringBoot Starter concept.

[00:07:44]Let's quickly recap.

[00:07:46]SpringBoot Starters solve the problem of dependency management and compatibility across different frameworks.

[00:07:54]Each Starter is a single dependency that automatically brings in all required libraries and versions.

[00:08:02]With SpringBoot 4, the Starter names have been modernized. For example, SpringBoot Starter Web MVC instead of the older SpringBoot Starter Web.

[00:08:12]These Starters make SpringBoot projects lightweight, version-safe, and easy to maintain.

[00:08:18]Letting you focus on writing business logic instead of configuration.

[00:08:23]In the next lecture, we'll take a closer look at the SpringBoot Starter parent and understand how it manages dependency versions and Maven plugins behind the scenes.

[00:08:34]All right. Great. I'll see you in the next lecture.