# Adding behaviors

Adding behaviors to the generated code is one area that still needs improvement. Your feedback is appreciated.

Suppose if JAXB generated the following classes.

Simple JAXB Generated Code

    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() { ... }
    }

To add a behavior, first write a class that extends from `Person`. 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 `PersonEx` class to be used in place of `Person`, and we don't want `PersonEx` to be bound to its own XML type.

Extended Person class

    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();
      }
    }

At runtime, you can create `JAXBContext` normally, like this.

Creating JAXBContext

    JAXBContext context = JAXBContext.newInstance(ObjectFactory.class);
    // or JAXBContext.newInstance("org.acme.foo");

`PersonEx` can be marshalled out just like `Person`:

Marshalling

    Person p = new PersonEx();
    context.createMarshaller().marshal(p,System.out);
    // this will produce <person />

To unmarshal XML documents into `PersonEx`, you'll need to configure the unmarshaller to use your `ObjectFactoryEx` as the factory, like this:

Unmarshalling

    Unmarshaller u = context.createUnmarshaller();
    u.setProperty("com.sun.xml.bind.ObjectFactory",new ObjectFactoryEx());
    PersonEx p = (PersonEx)u.unmarshal(new StringReader("<person />"));

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

## Inserting your class in the middle

If you have a type hierarchy and would like to insert your class in the middle, you can use the combination of `XmlTransient` and `@implClass` of `<class>` customization. See the following example:

Hierarchy of types and `<jaxb:class implClass>`

    <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>

This creates a class hierarchy like the following (among the generated Java code):

                Vehicle
                   ^
                   |
                MyVehicle
                   ^
              _____|______
             |            |
            Car          Bicycle

You'll then manually write `MyVehicle` class that extends from `Vehicle`. Annotate this class with `XmlTransient` to achieve the desired effect.