How to Learn Spring Boot in 2026

If you are stepping into the Java ecosystem in 2026, you are arriving at an exciting time. With the release of Spring Boot 4 and the maturity of Java 25, the "heavy" enterprise Java of the past is gone. Today, it’s about instant startup times, AI integration, and virtual threads.

Here is my streamlined roadmap for mastering Spring Boot this year.

1. The Prerequisites: Modern Java First

Don't start with Java 8. In 2026, the baseline for Spring Boot 4 is Java 17, but you should really be coding in Java 21 or 25.

Records: For cleaner DTOs (Data Transfer Objects).
Virtual Threads (Project Loom): This is the biggest game-changer. You no longer need complex reactive code (WebFlux) for high concurrency; standard blocking code is now highly scalable.
Pattern Matching & Sealed Classes: For more expressive domain modeling.

2. Phase 1: Core Fundamentals (Spring Boot 4)

Skip the legacy XML configurations. Focus entirely on annotation-based config and the "Magic" of Spring Boot.

Dependency Injection (IoC): Understand how Spring manages objects (Beans).
Starters: Learn how spring-boot-starter-web and others auto-configure your app.
Actuator: Observability is native now. Learn to expose metrics and health checks from day one.

3. Phase 2: Data & Intelligence

The database layer has evolved. While JPA/Hibernate is still king, the way we access data is faster.

Spring Data JPA: Learn Repository interfaces.
Spring AI: This is the new essential. Learn how to integrate LLMs (Large Language Models) directly into your Spring services for RAG (Retrieval-Augmented Generation) applications.
Docker Compose Support: Spring Boot 4 can now automatically spin up your database containers (PostgreSQL, MongoDB) during development.

4. Phase 3: Production Engineering

In 2026, "working on my machine" isn't enough. You need to build for the cloud.

GraalVM Native Images: Learn how to compile your Java app into a native binary that starts in milliseconds (crucial for Serverless/AWS Lambda).
Spring Security 6+: Focus on OAuth2 and OIDC (OpenID Connect). Basic Auth is rarely sufficient anymore.
Testing: Master JUnit 5 and Testcontainers. Mocking is good, but testing against real containerized databases is the 2026 standard.

Summary Checklist

[ ] Install JDK 25 & IntelliJ IDEA
[ ] Build a REST API with Spring Boot 4
[ ] Connect to PostgreSQL using Docker Compose
[ ] Secure endpoints with Spring Security
[ ] Build a Native Image with GraalVM

Spring Boot remains the undisputed king of backend frameworks. Focus on the modern features, ignore the legacy noise, and start building.