Should you use RestClient.create() or inject a RestClient.Builder in Spring Boot? The answer matters more than you think, especially when it comes to observability, metrics, and auto-configuration.

In this tutorial, we explore the difference between calling RestClient.create() directly and injecting the auto-configured RestClient.Builder that Spring Boot provides. Along the way, we dive into the Builder Pattern in Java by looking at what problem it solves, how it works, and why Spring uses it extensively. By the end, you'll understand exactly what Spring Boot is doing behind the scenes and when to use each approach.

- Understand the difference between RestClient.create() and injecting RestClient.Builder
- Learn the Java Builder Pattern from scratch with a practical social media post example
- Discover what Spring Boot auto-configures for you with RestClientAutoConfiguration
- Know why the injected builder includes observability, message converters, and customizers
- See how to make HTTP calls using RestClient in a Spring Boot application

If you learned something new today, leave a thumbs up, subscribe to the channel, and let me know in the comments... Are you using RestClient yet or still on RestTemplate?

0:00 - Intro & the question from Spring Office Hours
1:05 - Why RestClient over RestTemplate
1:45 - Setting up the project on start.spring.io
2:30 - Using RestClient.create() with a static factory method
3:45 - Making an HTTP GET call to JSON Placeholder
4:30 - The Builder Pattern in Java — why it exists
5:00 - Java Beans approach (mutable, verbose)
5:50 - Telescoping constructors approach
6:45 - Builder Pattern with immutable fields
8:15 - Applying the Builder Pattern to RestClient.Builder
9:00 - Spring auto-configures DefaultRestClientBuilder
9:45 - Why inject Builder instead of calling create()
10:30 - Observability, metrics, and customizers
11:15 - When you might want manual control
11:50 - Wrap up & recommendations

🔗Resources & Links mentioned in this video:
GitHub Repository: https://github.com/danvega/rcbuilder
Spring Office Hours: https://springofficehours.io
JSON Placeholder API: https://jsonplaceholder.typicode.com
Spring Boot RestClient Documentation: https://docs.spring.io/spring-framework/reference/integration/rest-clients.html

👋🏻Connect with me:
Website: https://www.danvega.dev
Twitter: https://twitter.com/therealdanvega
Github: https://github.com/danvega
LinkedIn: https://www.linkedin.com/in/danvega
Newsletter: https://www.danvega.dev/newsletter

SUBSCRIBE TO MY CHANNEL: http://bit.ly/2re4GH0 ❤️

Dan Vega

Explains when to use Spring Boot's RestClient static factory methods versus the auto-configured RestClient.Builder. Covers the builder pattern in Java using a social media post example, then applies it to RestClient. Key takeaway: injecting the Spring-auto-configured RestClient.Builder is preferred because it comes preloaded with message converters, RestClientCustomizer beans, observability/metrics integration (Micrometer, OpenTelemetry), and connection pool settings — benefits you miss when calling RestClient.create() directly.

Spring Boot RestClient.Builder Explained (Builder Pattern)