RestTemplate client with cookies

Question

I'm writing a simple client in Java to allow reusable use of proprietary virus scanning software accessible through a RESTful API. To upload a file for scanning the API requires a POST for Connect, followed by a POST for Publishing the file to the server. In the response to the Connect POST there are cookies set by the server which need to be present in the subsequent POST for publishing the file. I'm currently using Spring RestTemplate in my client.

My question is how do I access the cookies in the response to forward back to the server with the subsequent POST? I can see that they are present in the header that is returned but there are no methods on the ResponseEntity to access them.

Answer 1

RestTemplate has a method in which you can define Interface ResponseExtractor<T>, this interface is used to obtain the headers of the response, once you have them you could send it back using HttpEntity and added again.

 .add("Cookie", "SERVERID=c52");

Try something like this.

String cookieHeader = null;

new ResponseExtractor<T>(){
      T extractData(ClientHttpResponse response) {
        response.getHeaders();
      }
}

Then

  HttpHeaders headers = new HttpHeaders();
  headers.add("Cookie", cookieHeader );

  ResponseEntity<byte[]> response = restTemplate.exchange("http://example.com/file/123",
      GET,
      new HttpEntity<String>(headers),
      byte[].class);

Also read this post

Answer 2

I've solved the problem by creating an interceptor which stores a cookie and puts it in next requests.

public class StatefulRestTemplateInterceptor implements ClientHttpRequestInterceptor {
    private String cookie;

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        if (cookie != null) {
            request.getHeaders().add(HttpHeaders.COOKIE, cookie);
        }
        ClientHttpResponse response = execution.execute(request, body);

        if (cookie == null) {
            cookie = response.getHeaders().getFirst(HttpHeaders.SET_COOKIE);
        }
        return response;
    }
}

Set the interceptor for your RestTemplate:

@Bean
public RestTemplate restTemplate(RestTemplateBuilder templateBuilder) {
    return templateBuilder
            .requestFactory(new BufferingClientHttpRequestFactory(new HttpComponentsClientHttpRequestFactory()))
            .interceptors(new StatefulRestTemplateInterceptor())
            .build();
}