RestTemplate Interceptor

Question

I'm currently trying to incorporate a HandlerInterceptorAdapter but it's not getting registered and comparing it to other answers is tough because everyone is using something different. And I'm aware WebMvcConfigureAdapter is deprecated, some versioning is beyond my control for the scope of the project, see usage specs below.

Can someone please provide some guidance on incorporating interceptors with a RestTemplate (that's not ClientHttpRequestInterceptor).

Main:

@SpringBootApplication
@EnableRetry
public class Application extends SpringBootServletInitializer {

  public static void main(String[] args) {

   ApplicationContext ctx = SpringApplication.run(Application.class, args);

  }


  @Override
  protected SpringApplicationBuilder configure(SpringApplicationBuilder applicationBuilder) {

    return applicationBuilder.sources(Application.class);

  }

  @Bean
  private RestTemplate restTemplate(){
    Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("redacted", 8080));

    SimpleClientHttpRequestFactory simpleClientHttpRequestFactory = new SimpleClientHttpRequestFactory();
    simpleClientHttpRequestFactory.setProxy(proxy);
    simpleClientHttpRequestFactory.setOutputStreaming(false);

    RestTemplate template = new RestTemplate();
    template.setErrorHandler(new MyResponseErrorHandler());

    return template;
  }
}

Interceptor : com.example.foo.config.request.interceptor

@Component
public class MyInterceptor extends HandlerInterceptorAdapter {

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    System.out.println("INTERCEPTED");
    return super.preHandle(request, response, handler);
  }
}

InterceptorConfig : com.example.foo.config.request.interceptor

@Configuration
public class InterceptorConfig extends WebMvcConfigurerAdapter  {

  @Bean
  MyInterceptor myInterceptor() {
    return new MyInterceptor();
  }

  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    super.addInterceptors(registry);
    System.out.println("Adding interceptor");
    registry.addInterceptor(myInterceptor());
  }

}

"Adding interceptor" does get logged so I know the configs are being scanned. I just can't get any interceptor logic to log.

Using:

• Spring Boot v1.5.15
• Spring Version: 4.3.18.RELEASE

Answer 1

RestTemplate expects ClientHttpRequestInterceptor

setInterceptors(List<ClientHttpRequestInterceptor> interceptors)

Set the request interceptors that this accessor should use.

You can use Servlet Filter to "intercept" requests/response,

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
    HttpServletRequest httpRequest = (HttpServletRequest) request;
    HttpServletResponse httpResponse = (HttpServletResponse) response;

implement this with a servlet filter. No Spring involved here at all

But you will have to change RestTemplate to using other framework as jersey

Jersey gives a very handy implementation of such as filter called LoggingFilter which can help in logging all kinds of incoming and outgoing traffic.

Answer 2

HandlerInterceptorAdapter is an implementation that applies to @Controller or @RestController. Not an implementation for RestTemplete.

To apply it to RestTemplete, you need to use ClientHttpRequestInterceptor.

ex.

@Component
public class CustomInterceptor implements ClientHttpRequestInterceptor {
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        // ... 
    }
}

@Configuation
public class RestTempleteConfig {

    // ...
    @Autowired
    private CustomInterceptor customInterceptor;

    @Bean
    public RestTemplate restTemplate(){
        RestTemplate template = new RestTemplate();
        List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
        template.add(customInterceptor);
        return template;
    }
}