Programming

Using Jackson as JSON provider in Jersey 2.x

When producing and consuming JSON in a Jersey application, will need a JSON provider, otherwise you’ll see an error like this:

A message body writer for Java class ... and MIME media type application/json was not found

At time of writing, Jersey 2.x integrates with the following modules to provide JSON support:

Among the options mentioned above, I would say Jackson is the one which offers more features when parsing JSON.

Using Jackson #

See below the steps to use Jackson, a popular Java parser for Java, as a JSON provider in Jersey 2.x:

Adding Jackson module dependencies #

To use Jackson 2.x as your JSON provider you need to add jersey-media-json-jackson module to the pom.xml file:

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
    <version>2.23.1</version>
</dependency>

To use Jackson 1.x, add the jersey-media-json-jackson1 artifact to the pom.xml file:

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson1</artifactId>
    <version>2.23.1</version>
</dependency>

Registering Jackson module #

Besides adding the dependency mentioned above, you need to register JacksonFeature (or Jackson1Feature for Jackson 1.x) in your Application / ResourceConfig sub-class:

@ApplicationPath("/api")
public class MyApplication extends Application {

    @Override
    public Set<Class<?>> getClasses() {
        Set<Class<?>> classes = new HashSet<Class<?>>();
        classes.add(JacksonFeature.class);
        return classes;
    }
}

@ApplicationPath("/api")
public class MyApplication extends ResourceConfig {

    public MyApplication() {
        register(JacksonFeature.class);
    }
}

If you don’t have an Application / ResourceConfig sub-class, you can register the JacksonFeature in your web.xml deployment descriptor by adding the feature fully-qualified class name to the jersey.config.server.provider.classnames initialization parameter:

<init-param>
    <param-name>jersey.config.server.provider.classnames</param-name>
    <param-value>org.glassfish.jersey.jackson.JacksonFeature</param-value>
</init-param>

If you need to register other features, resources or providers, separate their fully-qualified class names with comma (,).

Just in case you are interested in having a look at the implementation, the MessageBodyWriter provided by Jackson is JacksonJsonProvider.

For more details, check the Jersey documentation about support for common media type representations.