http-interface-clients

HTTP Interface Clients

Spring Boot 4 introduces the @ImportHttpServices annotation, enabling zero-boilerplate declarative HTTP clients using @HttpExchange interfaces.

Overview

HTTP Interface Clients allow you to define REST clients as simple interfaces with declarative annotations. Spring Boot 4's @ImportHttpServices eliminates all the manual configuration previously required.

Key Concepts

• Zero configuration: @ImportHttpServices handles all bean registrations automatically
• Declarative interfaces: Define HTTP calls as method signatures with @HttpExchange
• Type-safe: Full compile-time checking with Java records
• Clean architecture: Separate interface definitions from implementation

Resources

GitHub Repository

https://github.com/danvega/sb4-http-interfaces

Video Tutorial

https://youtu.be/TEd5e4Thu7M

Blog Post

https://www.danvega.dev/blog/http-interfaces-spring-boot-4

Official Documentation

• Spring Framework HTTP Interface

Example Usage

Before (Manual Configuration)

@Bean
public TodoService todoService(RestClient.Builder restClientBuilder) {
    var restClient = restClientBuilder
            .baseUrl("https://jsonplaceholder.typicode.com")
            .build();

    var adapter = RestClientAdapter.create(restClient);
    var factory = HttpServiceProxyFactory.builderFor(adapter).build();
    return factory.createClient(TodoService.class);
}

After (Spring Boot 4)

@Configuration(proxyBeanMethods = false)
@ImportHttpServices(TodoService.class)
public class HttpClientConfig {
    // That's it!
}

Interface Definition

@HttpExchange(url = "https://jsonplaceholder.typicode.com", accept = "application/json")
public interface TodoService {
    @GetExchange("/todos")
    List<Todo> getAllTodos();

    @GetExchange("/todos/{id}")
    Todo getTodoById(@PathVariable Long id);

    @PostExchange("/todos")
    Todo createTodo(@RequestBody Todo todo);
}