XML wrapped list to JSON array via Jettison and JAXB

Question

I'm using JAXB to marshal an annotated object to XML in the form:

  <channels>
     <channel>Test A</channel>
     <channel>Test B</channel>
  </channels>

I want to marshal this to JSON instead using JAXB (ala http://blog.bdoughan.com/2011/04/jaxb-and-json-via-jettison.html) but it marshals to something like the following:

  "channels" : {
    "channel" : [ "Test A", "Test B" ]
  },

Really I want it to marshal into the following form:

  "channels" : {
    {"Test A"}, {"Test B"}
  },

How can I do this? Is it the right thing to do?

Answer 1

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB 2 (JSR-222) expert group.

Below is how you could support this use case using the JSON-binding in EclipseLink JAXB (MOXy).

Java Model (Root)

Below is the Java model that I will use for this example.

import java.util.*;
import javax.xml.bind.annotation.*;

@XmlRootElement
public class Root {

    private List<String> channels = new ArrayList<String>();

    @XmlElementWrapper
    @XmlElement(name="channel")
    public List<String> getChannels() {
        return channels;
    }

}

Specify MOXy as the JAXB Provider (jaxb.properties)

To specify MOXy as your JAXB provider you need to include a file called jaxb.properties in the same package as your domain model with the following entry (see: ):

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

Demo Code

In the demo code below we will output the same instance to both XML and JSON.

import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.MarshallerProperties;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Root.class);
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        Root root = new Root();
        root.getChannels().add("Test A");
        root.getChannels().add("Test B");

        // Output XML
        marshaller.marshal(root, System.out);

        // Output JSON
        marshaller.setProperty(MarshallerProperties.MEDIA_TYPE, "application/json");
        marshaller.setProperty(MarshallerProperties.JSON_INCLUDE_ROOT, false);
        marshaller.setProperty(MarshallerProperties.JSON_WRAPPER_AS_ARRAY_NAME, true);
        marshaller.marshal(root, System.out);
    }

}

Output

Below is the output from running the demo code:

<?xml version="1.0" encoding="UTF-8"?>
<root>
   <channels>
      <channel>Test A</channel>
      <channel>Test B</channel>
   </channels>
</root>

{
   "channels" : [ "Test A", "Test B" ]
}

For More Information

• http://blog.bdoughan.com/2013/03/binding-to-json-xml-handling-collections.html