What's New in Spring Boot 3: Complete Feature Guide

📌Introduction

Spring Boot 3 is a major release bringing Java 17 baseline, GraalVM native compilation, and many improvements. Let's explore what's new.

Spring Boot 3 requires Java 17 minimum, bringing:

Records for immutable data classes

Sealed classes for controlled inheritance

Pattern matching for instanceof

Text blocks for multi-line strings

Compile to native executables:

Instant startup (milliseconds)

Reduced memory footprint

Smaller container images

Ideal for serverless

Namespace change from javax.* to jakarta.*:

Update your imports

Check third-party library compatibility

Use migration tools if needed

Built-in observability with Micrometer:

Metrics out of the box

Distributed tracing

Log correlation

Grafana dashboard templates

Declarative HTTP clients:

@HttpExchange("/users")
interface UserClient {
    @GetExchange("/{id}")
    User getUser(@PathVariable Long id);
}

Standardized error responses:

{
  "type": "/errors/not-found",
  "title": "User Not Found",
  "status": 404,
  "detail": "User with ID 123 not found"
}

1Update to Java 17 first

2Update Spring Boot to 2.7.x

3Fix deprecation warnings

4Then upgrade to 3.x

5Update Jakarta imports

Our Spring Boot course covers all these new features with practical examples.