Spring Web Java 25 · Spring Boot 4.1.1

Spring Web: Retry with RestClient

Submodule: web-rest-retry

This tutorial demonstrates how to use Spring Retry with the modern RestClient in a Spring Boot application.

Implementation Details

First, we define a simple User record to represent the response from the JSONPlaceholder API.

record User(Long id, String name, String username, String email) {
}

Next, we create the UserService and inject a RestClient.Builder configured with the base URL. We use the @EnableResilientMethods and @Retryable annotations to enable retry mechanism. findAll is specified to handle HttpServerErrorException (5xx errors).

@Service
@EnableResilientMethods
class UserService {

    private final RestClient restClient;

    public UserService(RestClient.Builder restClientBuilder) {
        this.restClient = restClientBuilder.baseUrl("https://jsonplaceholder.typicode.com").build();
    }

    @Retryable(includes = HttpServerErrorException.class)
    public List<User> findAll() {
        return this.restClient.get()
            .uri("/users")
            .retrieve()
            .body(new ParameterizedTypeReference<>() {});
    }

}

Integration Testing

To verify the retry logic, we use @RestClientTest along with MockRestServiceServer.

@RestClientTest(UserService.class)
class UserServiceTests {

    @Autowired
    private UserService userService;

    @Autowired
    private MockRestServiceServer server;

    @Test
    @DisplayName("Given the API returns 500 twice When getting users Then it should retry and succeed on the third attempt")
    void findAllWithFailures() throws Exception {
        var response = """
                       [{
                         "id": 1,
                         "name": "Leanne Graham",
                         "username": "Bret",
                         "email": "[email protected]"
                       }]
                       """;

        server.expect(requestTo("https://jsonplaceholder.typicode.com/users"))
              .andRespond(withServerError());

        server.expect(requestTo("https://jsonplaceholder.typicode.com/users"))
              .andRespond(withServerError());

        server.expect(requestTo("https://jsonplaceholder.typicode.com/users"))
              .andRespond(withSuccess(response, MediaType.APPLICATION_JSON));

        List<User> users = this.userService.findAll();

        assertThat(users).hasSize(1)
                .first()
                .extracting("name").isEqualTo("Leanne Graham");

        server.verify();
    }

}