Extending JAXB - Representing Metadata as JSON

• You cannot modify the domain model (it may come from a 3rd party).
• You do not want to introduce compile dependencies on JAXB APIs (if you are using a version of Java prior to Java SE 6).
• You want to apply multiple JAXB mappings to a domain model (you are limited to one representation with annotations).
• Your object model already contains so many annotations from other technologies that adding more would make the class unreadable.

Domain Model

The following domain model will be used in this example. Because the JAXB metadata is represented as JSON, no annotations are used on the classes.

Customer

package blog.bindingfile;
 
import java.util.List;
  
public class Customer {
 
    private String firstName;
    private String lastName;
    private Address address;
    private List<PhoneNumber> phoneNumbers;
 
    public String getFirstName() {
        return firstName;
    }
 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    public String getLastName() {
        return lastName;
    }
 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    public Address getAddress() {
        return address;
    }
 
    public void setAddress(Address address) {
        this.address = address;
    }
 
    public List<PhoneNumber> getPhoneNumbers() {
        return phoneNumbers;
    }
 
    public void setPhoneNumbers(List<PhoneNumber> phoneNumbers) {
        this.phoneNumbers = phoneNumbers;
    }
 
}

package blog.bindingfile;
 
public class Address {
 
    private String street;
 
    public String getStreet() {
        return street;
    }
 
    public void setStreet(String street) {
        this.street = street;
    }
 
}

package blog.bindingfile;
 
public class PhoneNumber {
  
    private String type;
    private String number;
 
    public String getType() {
        return type;
    }
 
    public void setType(String type) {
        this.type = type;
    }
 
    public String getNumber() {
        return number;
    }
 
    public void setNumber(String number) {
        this.number = number;
    }
 
}

The following JSON input will be used in this example:

{
   "first-name" : "Jane",
   "last-name" : "Doe",
   "address" : {
      "street" : "123 A Street"
   },
   "phone-number" : [ {
      "type" : "work",
      "value" : "555-1111"
   }, {
      "type" : "cell",
      "value" : "555-2222"
   } ]
}

The JSON mapping file is passed in via the properties parameter when the JAXBContext is instantiated.

package blog.bindingfile;
  
import java.io.File;
import java.util.*;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;
import org.eclipse.persistence.jaxb.JAXBContextFactory;
 
public class Demo {
 
    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(3);
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, "blog/bindingfile/binding.json");
        properties.put("eclipselink.media-type", "application/json");
        properties.put("eclipselink.json.include-root", false);
        JAXBContext jc = JAXBContext.newInstance("blog.bindingfile", Customer.class.getClassLoader() , properties);
 
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        StreamSource json = new StreamSource(new File("src/blog/bindingfile/input.json"));
        Customer customer = (Customer) unmarshaller.unmarshal(json, Customer.class).getValue();
 
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(customer, System.out);
    }
 

In order to use this extension, you must use MOXy as your JAXB provider.  To enable MOXy simply add a file named jaxb.properties in the same package as your domain classes with the following entry:

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