How to use RESTEasy PreProcessInterceptor only in

问题:

I'm writing a REST API, making use of RestEasy 2.3.4.Final. I know that a Interceptor will intercept all of my requests, and that a PreProcessInterceptor will be the first (before everything) to be called. I would like to know how can I make this Interceptor to be called just when specific methods are called.

I tried to use both PreProcessInterceptor and AcceptedByMethod, but I was not able to read the parameters I need. For example, I need to run my Interceptor only when this method is called:

@GET
@Produces("application/json;charset=UTF8")
@Interceptors(MyInterceptor.class)
public List<City> listByName(@QueryParam("name") String name) {...}

To be more specific, I need to run my Interceptor in all methods whose have a @QueryParam("name")

on its signature, so that I can grab the name and do something before everything.

Is it possible? I tried to catch the "name" parameter inside the Interceptor, but I was not able to do that.

Could someone help me, please?

回答1:

You can use AcceptedByMethod as explained in the RESTEasy documentation

Create a class that implement both PreProcessInterceptor and AcceptedByMethod. In the accept-method, you can check if the method has a parameter with annotated with @QueryParam("name"). If the method has that annotation, return true from the accept-method.

In the preProcess-method, you can get the query parameter from request.getUri().getQueryParameters().getFirst("name").

EDIT:

Here is an example:

public class InterceptorTest  {

    @Path("/")
    public static class MyService {

        @GET
        public String listByName(@QueryParam("name") String name){
            return "not-intercepted-" + name;
        }
    }

    public static class MyInterceptor implements PreProcessInterceptor, AcceptedByMethod {

        @Override
        public boolean accept(Class declaring, Method method) {
            for (Annotation[] annotations : method.getParameterAnnotations()) {
                for (Annotation annotation : annotations) {
                    if(annotation.annotationType() == QueryParam.class){
                        QueryParam queryParam = (QueryParam) annotation;
                        return queryParam.value().equals("name");
                    }
                }
            }
            return false;
        }

        @Override
        public ServerResponse preProcess(HttpRequest request, ResourceMethod method)
                throws Failure, WebApplicationException {

            String responseText = "intercepted-" + request.getUri().getQueryParameters().getFirst("name");
            return new ServerResponse(responseText, 200, new Headers<Object>());
        }
    }

    @Test
    public void test() throws Exception {
        Dispatcher dispatcher = MockDispatcherFactory.createDispatcher();
        dispatcher.getProviderFactory().getServerPreProcessInterceptorRegistry().register(new MyInterceptor());
        dispatcher.getRegistry().addSingletonResource(new MyService());

        MockHttpRequest request = MockHttpRequest.get("/?name=xxx");
        MockHttpResponse response = new MockHttpResponse();

        dispatcher.invoke(request, response);

        assertEquals("intercepted-xxx", response.getContentAsString());
    }
}

回答2:

if you return return new ServerResponse(responseText, 200, new Headers<Object>()); you will lose the end-point. you need to return null if you still want the message to be delivered to the final point.