Spring: how to get rootUri from RestTempalte

Question

I'm using this configuration class to initialize RestTemplate:

@Configuration
public class RestTemplateConfig {

  @Value("${endpoint-url}")
  private String endpointUrl;

  @Bean
  public RestTemplate restTemplate(RestTemplateBuilder builder) {
    return builder
        .rootUri(endpointUrl)
        .messageConverters(new MappingJackson2HttpMessageConverter())
        .build();
  }
}

And in one of my service's method I use the code:

RootUriTemplateHandler handler = (RootUriTemplateHandler) restTemplate.getUriTemplateHandler();
String uri = handler.getRootUri();
restTemplate.postForLocation(uri, request);

To get this URI. Is there an easier method to get this rootUri (without casting)? Or to execute the post request directly to rootUri?

Answer 1

restTemplate.getUriTemplateHandler().expand("/")

Answer 2

You can execute the post request directly to rootUri, as long as the uri you provide to the restTemplate.postForLocation starts with "/". In that case, Spring will automatically add the baseURI provided in the restTemplate constructor.

@Configuration
public class RestTemplateConfig {

   @Bean
   public RestTemplate restTemplate(RestTemplateBuilder builder,
                                    @Value("${endpoint-url}") String endpointUrl) {
     return builder
       .rootUri(endpointUrl)
       .messageConverters(new MappingJackson2HttpMessageConverter())
       .build();
   }
}

In your service's method:

// Make a POST call to ${endpoint-url}/foobar

String uri = "/foobar"; // The leading "/" is important!
restTemplate.postForLocation(uri, request);

Answer 3

Sounds like you are trying to use RestTemplate to pass along the value of ${endpoint-url}. That slightly awkward looking cast works but you could perhaps consider one of these alternatives:

• Create a provider which encapsulates the endpointUrl and your restTemplate and inject this provider wherever you need either the endpointUrl or the restTemplate. For example:

  @Component
  public class RestTemplateProvider {
  
      @Value("${endpoint-url}")
      private String endpointUrl;
  
      private final RestTemplate restTemplate;
  
      @Autowired
      public RestTemplateProvider(RestTemplateBuilder restTemplateBuilder) {
          this.restTemplate = restTemplateBuilder.rootUri(endpointUrl)
                  .messageConverters(new MappingJackson2HttpMessageConverter())
                  .build();
      }
  
      public RestTemplate provide() {
          return restTemplate;
      }
  
      public String getEndpointUrl() {
          return endpointUrl;
      }
  }
  

• Inject @Value("${endpoint-url}") private String endpointUrl; into which ever service class needs it.