[FIXED] Set default content type header of Spring RestTemplate

Issue

I'm currently using an OAuth2RestOperations that extends the Spring RestTemplate and I would like to specify the content type header.

The only thing I've managed to do was to explicitly set my header during the request:

public String getResult() {
    String result = myRestTemplate.exchange(uri, HttpMethod.GET, generateJsonHeader(), String.class).getBody();
}

private HttpEntity<String> generateJsonHeader() {
    HttpHeaders headers = new HttpHeaders();
    headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
    return new HttpEntity<>("parameters", headers);
}

But it would actually be great to be able to set that once and for all during the bean initialization, and directly use the getforObject method instead of exchange.

Solution

First you have to create request interceptor:

public class JsonMimeReqInterceptor implements ClientHttpRequestInterceptor {

  @Override
  public ClientHttpResponse intercept(HttpRequest request, byte[] body,
        ClientHttpRequestExecution execution) throws IOException {
    HttpHeaders headers = request.getHeaders();
    headers.add("Accept", MediaType.APPLICATION_JSON);
    return execution.execute(request, body);
  }
}

... and then you have rest template creation code which uses above interceptor:

@Configuration
public class MyAppConfig {

  @Bean
  public RestTemplate restTemplate() {
      RestTemplate template = new RestTemplate(clientHttpRequestFactory());
      //magic happens below:
      template.setInterceptors(Collections.singletonList(new JsonMimeReqInterceptor()));
      return restTemplate;
  }
}

You could subclass RestTemplate if you were to have some other specialised or universal REST templates in your application.

Answered By - diginoise