Java Web Services: Up and Running, 2nd Edition

A Standalone JAX-B Example

Recall that the B in JAX-B stands for data binding, the associating of a Java data type such as String to an XML Schema (or equivalent) type, in this case xsd:string. There are built-in bindings for the Java primitive types such as int and double together with String and Calendar; arrays (including Collections) of any such types; and programmer-defined types that reduce, via properties, to any of the preceding. The surprising omission is the Map, a collection of key/value pairs, but a Map is readily handled as two coordinated collections: a collection of keys and a corresponding collection of values. An example of JAX-B in action may help to drive these points home.

The Skier class (see Example 3-4) is annotated with @XmlRootElement to inform the JAX-B utilities that a Skier instance should be transformed into an XML document that has skier as its root or document (that is, outermost) element. In the default Java naming convention, the root element is the lowercase version of the class name; hence, Skier becomes skier. The annotation could be amended:

@XmlRootElement(name = "NordicSkier")

so that the root element has a specified name, in this example NordicSkier.

Example 3-4. The annotated Skier POJO class

import javax.xml.bind.annotation.XmlRootElement;
import java.util.Collection;

@XmlRootElement
public class Skier  {
    private Person person;
    private String nationalTeam;
    private Collection majorAchievements;
    public Skier() { } // required for unmarshaling