August 11, 2012

JAXB's @XmlTransient and Property Order

In previous articles I wrote about how the @XmlTransient annotation can be used at the type level to have a class excluded from the inheritance hierarchy, or at the field/property level to unmap a field/property.  In this article I'll demonstrate how doing this impacts the propOrder setting on the @XmlType annotation.

Java Model

Base

This class will serve as the root of the inheritance hierarchy.  This will be a mapped class, and as such there is nothing special we need to do, to make this happen.
package blog.proporder.xmltransient;

public abstract class Base {

    private int id;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

}

Person

To exclude a class from being mapped as part of the inheritance hierarchy you simply need to annotate it with @XmlTransient.   Any super classes of this class that are not annotated with @XmlTransient (i.e. Base) will still be mapped.
package blog.proporder.xmltransient;

import javax.xml.bind.annotation.XmlTransient;

@XmlTransient
public class Person extends Base {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

Customer

Since the parent class (Person) has been marked @XmlTransient the name property will be treated as part of the Customer class and can be included in the propOrder.  The Customer class also extends Base which was not marked @XmlTransient so the id property can not be specified in the propOrder.  The propOrder setting must not include a field/property that has been annotated with @XmlTransient.
package blog.proporder.xmltransient;

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

@XmlRootElement
@XmlType(propOrder = { "phoneNumbers", "name"})
public class Customer extends Person {

    private String password;
    private List<String> phoneNumbers;

    @XmlTransient
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @XmlElement(name = "phone-number")
    public List<String> getPhoneNumbers() {
        return phoneNumbers;
    }

    public void setPhoneNumbers(List<String> phoneNumbers) {
        this.phoneNumbers = phoneNumbers;
    }

    
}

Demo Code

Below is the demo code that can be used to run this example:
package blog.proporder.xmltransient;

import java.io.File;
import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Customer.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("input.xml");
        Customer customer = (Customer) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(customer, System.out);
    }

}

XML (input.xml/Output)

Below is the input to, and output from running the demo code.  Note how the properties of classes marked with @XmlTransient are included, but properties marked @XmlTransient are not.
<?xml version="1.0" encoding="UTF-8"?>
<customer>
   <id>123</id>
   <phone-number>555-1111</phone-number>
   <phone-number>555-2222</phone-number>
   <name>Jane Doe</name>
</customer>

Further Reading

If you enjoyed this post you may also be interested in:

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