java - Custom ObjectMapper with Jersey 2.2 and Jackson 2.1

Question

I am struggling with a REST application with Grizzly, Jersey and Jackson, because Jersey ignores my custom ObjectMapper.

POM dependencies:

<dependencies>
    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-grizzly2-servlet</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.jaxrs</groupId>
        <artifactId>jackson-jaxrs-json-provider</artifactId>
        <version>2.1.4</version>
    </dependency>
</dependencies>

Resulting versions are: Grizzly 2.3.3, Jackson 2.1.4 and Jersey 2.2.

Main class (I want explicit registration of Jersey components):

public class Main {
    public static void main(String[] args) {
        try {
            ResourceConfig rc = new ResourceConfig();
            rc.register(ExampleResource.class);
            rc.register(ObjectMapperResolver.class);

            HttpHandler handler = ContainerFactory.createContainer(
                    GrizzlyHttpContainer.class, rc);

            URI uri = new URI("http://0.0.0.0:8080/");

            HttpServer server = GrizzlyHttpServerFactory.createHttpServer(uri);

            ServerConfiguration config = server.getServerConfiguration();
            config.addHttpHandler(handler, "/");

            server.start();
            System.in.read();

        } catch (ProcessingException | URISyntaxException | IOException e) {
            throw new Error("Unable to create HTTP server.", e);
        }
    }
}

ContextResolver for ObjectMapper:

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class ObjectMapperResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper;

    public ObjectMapperResolver() {
        System.out.println("new ObjectMapperResolver()");
        mapper = new ObjectMapper();
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        System.out.println("ObjectMapperResolver.getContext(...)");
        return mapper;
    }

}

Neither ObjectMapperResolver constructor nor getContext get called. What am I missing? I would prefer to use Jersey 2.2 and Jackson 2.1, because it is a dependency for another lib.

A full example can be found on GitHub: https://github.com/svenwltr/example-grizzly-jersey-jackson/tree/stackoverflow

Answer 1

The following solution applies to the following stack (as in... this is the setup I've used to test it)

Jersey 2.12, Jackson 2.4.x

I'm adding my message w/ the solution I've come up with on this post since it was quite relevant for the many Google searches I've put in today... It is a cumbersome solution to what I believe to be an even more cumbersome problem.

1. Make sure your maven configuration CONTAINS the jackson-jaxrs-json-provider dependency:

<dependency>
    <groupId>com.fasterxml.jackson.jaxrs</groupId>
    <artifactId>jackson-jaxrs-json-provider</artifactId>
    <version>2.4.1</version>
</dependency>

2. Make sure your maven configuration DOESN'T CONTAIN the jersey-media-json-jackson dependency:

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
</dependency>

3. Create a @Provider component extending com.fasterxml.jackson.jaxrs.json.JacksonJaxbJsonProvider like so:

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.jaxrs.json.JacksonJaxbJsonProvider;

import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.ext.Provider;

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class CustomJsonProvider extends JacksonJaxbJsonProvider {

    private static ObjectMapper mapper = new ObjectMapper();

    static {
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
     }

    public CustomJsonProvider() {
        super();
        setMapper(mapper);
    }
}

As you can observe this is also where we define the custom instance of com.fasterxml.jackson.databind.ObjectMapper

4. Extend javax.ws.rs.core.Feature via MarshallingFeature like so:

import javax.ws.rs.core.Feature;
import javax.ws.rs.core.FeatureContext;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;

public class MarshallingFeature implements Feature {

    @Override
    public boolean configure(FeatureContext context) {
        context.register(CustomJsonProvider.class, MessageBodyReader.class, MessageBodyWriter.class);
        return true;
    }
}

5. You need to register this custom provider like so, provided you configure your application via org.glassfish.jersey.server.ResourceConfig like so:

import org.glassfish.jersey.server.ResourceConfig;
...

public class MyApplication extends ResourceConfig {

    public MyApplication() {

        ...
        register(MarshallingFeature.class);
        ...
     }
 }

Other notes and observations:

1. This solution applies whether you're using javax.ws.rs.core.Response to wrap your controller's responses or not.
2. Please make sure you carefully take into consideration (copy/paste) the following code snippets since the only "non-mandatory" so to speak bits are the ones regarding the custom configuration of the com.fasterxml.jackson.databind.ObjectMapper.

@jcreason

Sorry for dropping the ball on this one @jcreason, I hope you're still curios. So I checked out the code from last year and this is what I came up w/ to provide a custom mapper.

The problem was that during feature initalization any custom object mappers get disabled by some code in

org.glassfish.jersey.jackson.JacksonFeature:77 (jersey-media-json-jackson-2.12.jar)

// Disable other JSON providers.
context.property(PropertiesHelper.getPropertyNameForRuntime(InternalProperties.JSON_FEATURE, config.getRuntimeType()), JSON_FEATURE);

But this feature only gets registered by this component

org.glassfish.jersey.jackson.internal.JacksonAutoDiscoverable

if (!context.getConfiguration().isRegistered(JacksonFeature.class)) {
    context.register(JacksonFeature.class);
}

So what I did was to register my own feature which registeres my own object mapper provider and drops in a trip wire stopping org.glassfish.jersey.jackson.JacksonFeature from being registered and overriding my object mapper...

import com.fasterxml.jackson.jaxrs.base.JsonMappingExceptionMapper;
import com.fasterxml.jackson.jaxrs.base.JsonParseExceptionMapper;

import org.glassfish.jersey.internal.InternalProperties;
import org.glassfish.jersey.internal.util.PropertiesHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.ws.rs.core.Configuration;
import javax.ws.rs.core.Feature;
import javax.ws.rs.core.FeatureContext;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;

public class MarshallingFeature implements Feature {

    private final static String JSON_FEATURE = MarshallingFeature.class.getSimpleName();

    @Override
    public boolean configure(FeatureContext context) {

      context.register(JsonParseExceptionMapper.class);
      context.register(JsonMappingExceptionMapper.class);
      context.register(JacksonJsonProviderAtRest.class, MessageBodyReader.class, MessageBodyWriter.class);

      final Configuration config = context.getConfiguration();
      // Disables discoverability of org.glassfish.jersey.jackson.JacksonFeature
      context.property(
          PropertiesHelper.getPropertyNameForRuntime(InternalProperties.JSON_FEATURE,
                                                     config.getRuntimeType()), JSON_FEATURE);

      return true;
    }
}

And here is the custom object mapper provider...

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.jaxrs.json.JacksonJaxbJsonProvider;

import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.ext.Provider;

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class JacksonJsonProviderAtRest extends JacksonJaxbJsonProvider {

    private static ObjectMapper objectMapperAtRest = new ObjectMapper();

    static {
        objectMapperAtRest.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        objectMapperAtRest.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapperAtRest.configure(SerializationFeature.INDENT_OUTPUT, true); // Different from default so you can test it :)
        objectMapperAtRest.setSerializationInclusion(JsonInclude.Include.ALWAYS);
    }

    public JacksonJsonProviderAtRest() {
        super();
        setMapper(objectMapperAtRest);
    }
}