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## Chapter 21. JSON Support via Jackson

Besides the Jettision JAXB adapter for JSON, Resteasy also support integration with the Jackson project. Many users find the output from Jackson much much nicer than the Badger format or Mapped format provided by Jettison. Jackson lives at http://jackson.codehaus.org. It allows you to easily marshal Java objects to and from JSON. It has a Java Bean based model as well as JAXB like APIs. Resteasy integrates with the JavaBean model as described at this url: http://jackson.codehaus.org/Tutorial.

While Jackson does come with its own JAX-RS integration. Resteasy expanded it a little. To include it within your project, just add this maven dependency to your build. Resteasy supports both Jackson 1.9.x and Jackson 2.2.x. Read further on how to use each.

## 21.1. Using Jackson 1.9.x Outside of JBoss AS7

If you're deploying Resteasy outside of JBoss AS7 add the resteasy jackson provder to your WAR pom.xml build

        <dependency>
           <groupId>org.jboss.resteasy</groupId>
           <artifactId>resteasy-jackson-provider</artifactId>
           <version>3.0.9.Final</version>
        </dependency>

## 21.2. Using Jackson 1.9.x Inside of JBoss AS7

If you're deploying Resteasy with JBoss AS7, there's nothing you need to do except to make sure you've updated your AS7 distribution with the latest and greatest Resteasy. See the installation sectio of this documentation for more details.

## 21.3. Using Jackson 2.2.x Outside of JBoss AS7

If you're deploying Resteasy outside of JBoss AS7 add the resteasy jackson provder to your WAR pom.xml build

        <dependency>
           <groupId>org.jboss.resteasy</groupId>
           <artifactId>resteasy-jackson2-provider</artifactId>
           <version>3.0.9.Final</version>
        </dependency>

## 21.4. Using Jackson 2.2.x Inside of JBoss AS7

If you want to use Jackson 2.2.x inside of JBoss AS7 you'll have to create a jboss-deployment-structure.xml file within your WEB-INF directory. By default AS7 includes the Jackson 1.9.x JAX-RS integration, so you'll want to exclude it from your dependencies, and add the jackson2 ones.

    <jboss-deployment-structure>
        <deployment>
            <exclusions>
               <module name="org.jboss.resteasy.resteasy-jackson-provider"/>
            </exclusions>
            <dependencies>
                <module name="org.jboss.resteasy.resteasy-jackson2-provider" services="import"/>
            </dependencies>
        </deployment>
    </jboss-deployment-structure>

## 21.5. Additional Resteasy Specifics

The first extra piece that Resteasy added to the integration was to support "application/*+json". Jackson would only accept "application/json" and "text/json" as valid media types. This allows you to create json-based media types and still let Jackson marshal things for you. For example:

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

       @GET
       @Produces("application/vnd.customer+json")
       public Customer[] getCustomers() {}
    }

Another problem that occurs is when you are using the Resteasy JAXB providers alongside Jackson. You may want to use Jettison and JAXB to output your JSON instead of Jackson. In this case, you must either not install the Jackson provider, or use the annotation @org.jboss.resteasy.annotations.providers.NoJackson on your JAXB annotated classes. For example:

        @XmlRootElement
        @NoJackson
        public class Customer {...}

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

           @GET
           @Produces("application/vnd.customer+json")
           public Customer[] getCustomers() {}
        }

If you can't annotate the JAXB class with @NoJackson, then you can use the annotation on a method parameter. For example:

            @XmlRootElement
            public class Customer {...}

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

               @GET
               @Produces("application/vnd.customer+json")
               @NoJackson
               public Customer[] getCustomers() {}

               @POST
               @Consumes("application/vnd.customer+json")
               public void createCustomer(@NoJackson Customer[] customers) {...}
            }

## 21.6. Possible Conflict With JAXB Provider

If your Jackson classes are annotated with JAXB annotations and you have the resteasy-jaxb-provider in your classpath, you may trigger the Jettision JAXB marshalling code. To turn off the JAXB json marshaller use the @org.jboss.resteasy.annotations.providers.jaxb.IgnoreMediaTypes("application/*+json") on your classes.

## 21.7. JSONP Support

If you're using Jackson, Resteasy has JSONP that you can turn on by adding the provider `org.jboss.resteasy.plugins.providers.jackson.JacksonJsonpInterceptor` (Jackson2JsonpInterceptor if you're using the Jackson2 provider) to your deployments. If the media type of the response is json and a callback query parameter is given, the response will be a javascript snippet with a method call of the method defined by the callback parameter. For example:

    GET /resources/stuff?callback=processStuffResponse

will produce this response:

    processStuffResponse(<nomal JSON body>)

This supports the default behavior of jQuery.

You can change the name of the callback parameter by setting the callbackQueryParameter property.

## 21.8. Jackson JSON Decorator

If you are using the Jackson 2.2.x provider, Resteasy has provided a pretty-printing annotation simliar with the one in JAXB provider:

    org.jboss.resteasy.annotations.providers.jackson.Formatted

Here is an example:

    @GET
    @Produces("application/json")
    @Path("/formatted/{id}")
    @Formatted
    public Product getFormattedProduct()
    {
        return new Product(333, "robot");
    }

As the example shown above, the @Formatted annotation will enable the underlying Jackson option "SerializationFeature.INDENT_OUTPUT".

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