Companion module for Spring Boot 4 HTTP Service Clients: @HttpExchange Interfaces with RestClient (Complete Guide) on ankurm.com. Declarative @HttpExchange interfaces registered with @ImportHttpServices, configured through spring.http.serviceclient.<group>.*, with error handling, retries, authentication and tests.

Everything runs offline: the tests start a small stub upstream (stub/StubServer, JDK HttpServer) on a random port and the clients call it over real HTTP. Nothing talks to jsonplaceholder.typicode.com.

Versions


Spring Boot	4.1.2
Spring Framework	7.0.10
Spring Security	7.1.2 (managed by Boot)
Resilience4j (retry comparison only)	2.4.0
JDK	25 (LTS)

Run

export JAVA_HOME=/path/to/jdk-25
./scripts/run-all.sh      # mvn test; rewrites output/*.txt (11 tests)
./scripts/run-stub.sh     # optional: the stub on port 18601, to poke with curl

Files

Path	What
`src/main/java/.../client/`	the `@HttpExchange` interfaces (posts, params, flaky, resilient, bearer, api key, OAuth2, GitHub)
`src/main/java/.../config/HttpClientsConfig.java`	`@ImportHttpServices` groups and `RestClientHttpServiceGroupConfigurer` beans
`src/main/java/.../error/`	status handler, custom exceptions, `@RestControllerAdvice`
`src/main/java/.../stub/StubServer.java`	the local upstream
`src/main/resources/application.yml`	base URLs, timeouts, default headers, OAuth2 registration
`src/test/java/.../Step01..Step09*Test.java`	one test per article section; each writes its transcript
`output/01..09c-*.txt`	captured output quoted in the article