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<!DOCTYPE book [
<!ENTITY % ents SYSTEM "docbook.ent">
%ents;
]>
<section version="5.0" xml:id="compiling-xml-schema-adding-behaviors"
         xml:lang="en" xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:ns5="http://www.w3.org/1999/xhtml"
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         xmlns:ns="http://docbook.org/ns/docbook"
         xmlns:m="http://www.w3.org/1998/Math/MathML">
    <title>Adding behaviors</title>

    <para><emphasis>Adding behaviors to the generated code is one area that
    still needs improvement. Your feedback is appreciated.</emphasis></para>

    <para>Suppose if JAXB generated the following classes.</para>

    <example>
        <title>Simple JAXB Generated Code</title>

        <programlisting language="java"><![CDATA[package org.acme.foo;

@XmlRootElement
class Person {
  private String name;

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

@XmlRegistry
class ObjectFactory {
  Person createPerson() { ... }
}]]></programlisting>
    </example>

    <para>To add a behavior, first write a class that extends from
    <literal>Person</literal>. You also need to extend ObjectFactory to return this
    new class. Notice that neither classes have any JAXB annotation, and I put
    them in a separate package. This is because we'd like
    <literal>PersonEx</literal> class to be used in place of <literal>Person</literal>,
    and we don't want <literal>PersonEx</literal> to be bound to its own XML
    type.</para>

    <example>
        <title>Extended Person class</title>

        <programlisting language="java"><![CDATA[package org.acme.foo.impl;

class PersonEx extends Person {
  @Override
  public void setName(String name) {
    if(name.length()<3) throw new IllegalArgumentException();
    super.setName(name);
  }
}

@XmlRegistry
class ObjectFactoryEx extends ObjectFactory {
  @Override
  Person createPerson() {
    return new PersonEx();
  }
}]]></programlisting>
    </example>

    <para>At runtime, you can create <literal>JAXBContext</literal> normally, like
    this.</para>

    <example>
        <title>Creating JAXBContext</title>

        <programlisting language="java"><![CDATA[JAXBContext context = JAXBContext.newInstance(ObjectFactory.class);
// or JAXBContext.newInstance("org.acme.foo");]]></programlisting>
    </example>

    <para><literal>PersonEx</literal> can be marshalled out just like
    <literal>Person</literal>:</para>

    <example>
        <title>Marshalling</title>

        <programlisting language="java"><![CDATA[Person p = new PersonEx();
context.createMarshaller().marshal(p,System.out);
// this will produce <person />]]></programlisting>
    </example>

    <para>To unmarshal XML documents into <literal>PersonEx</literal>, you'll need
    to configure the unmarshaller to use your <literal>ObjectFactoryEx</literal> as
    the factory, like this:</para>

    <example>
        <title>Unmarshalling</title>

        <programlisting language="java"><![CDATA[Unmarshaller u = context.createUnmarshaller();
u.setProperty("com.sun.xml.bind.ObjectFactory",new ObjectFactoryEx());
PersonEx p = (PersonEx)u.unmarshal(new StringReader("<person />"));]]></programlisting>
    </example>

    <para>If you have multiple packages and thus multiple
    <literal>ObjectFactory</literal>s, you can pass in an array of them (<code>new
    Object[]{new OFEx1(),new OFEx2(),...}</code>.)</para>

    <section xml:id="Inserting_your_class_in_the_middle">
        <title>Inserting your class in the middle</title>

        <para>If you have a type hierarchy and would like to insert your class
        in the middle, you can use the combination of <link
        xlink:href="https://jaxb.dev.java.net/nonav/jaxb20-fcs/docs/api/index.html?javax/xml/bind/annotation//1.6.1XmlTransient.html"><literal>XmlTransient</literal></link>
        and <literal>@implClass</literal> of <link
        xlink:href="https://jaxb.dev.java.net/nonav/2.0/binding-customization/http.java.sun.com.xml.n/element/class.html"><literal>&lt;class&gt;</literal></link>
        customization. See the following example:</para>

        <example>
            <title>Hierarchy of types and <literal>&lt;jaxb:class implClass&gt;</literal></title>

            <programlisting language="xml"><![CDATA[<xs:schema ...>
  <xs:complexType name="vehicle">
    <xs:annotation><xs:appinfo>
      <jaxb:class implClass="MyVehicle" />
    </xs:appinfo></xs:annotation>
  </xs:complexType>

  <xs:complexType name="car">
    <xs:complexContent>
      <xs:extension base="vehicle" />
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="bicycle">
    <xs:complexContent>
      <xs:extension base="vehicle" />
    </xs:complexContent>
  </xs:complexType>
</xs:schema>]]></programlisting>
        </example>

        <example>
            <title>This creates a class hierarchy like the following (among
            the generated Java code):</title>

            <programlisting language=""><![CDATA[            Vehicle
               ^
               |
            MyVehicle
               ^
          _____|______
         |            |
        Car          Bicycle]]></programlisting>
        </example>

        <para>You'll then manually write <literal>MyVehicle</literal> class that
        extends from <literal>Vehicle</literal>. Annotate this class with <link
        xlink:href="https://jaxb.dev.java.net/nonav/jaxb20-fcs/docs/api/index.html?javax/xml/bind/annotation//1.6.1XmlTransient.html"><literal>XmlTransient</literal></link>
        to achieve the desired effect.</para>
    </section>
</section>
