1.7. Avoid strong databinding

Under some limited circumstances, a weaker databinding is preferable for various reasons. JAXB does offer a few ways for you to achieve this.

1.7.1. Avoid mapping to enum

The following customization will stop binding a simple type to a type-safe enum. This can be convenient when number of constants is too large to be an useful enum (by default, the JAXB spec won't generate enum with more than 256 constants, but even 100 might be too large for you.)

Avoid mapping one simple type
<xs:simpleType name="foo">
  <xs:annotation><xs:appinfo>
    <jaxb:typesafeEnumClass map="false" />
  </xs:appinfo></xs:annotation>
  <xs:restriction base="xs:string">
    <xs:enumeration value="x" />
    <xs:enumeration value="y" />
    <xs:enumeration value="z" />
  </xs:restriction>
</xs:simpleType>

To disable such type-safe enum binding altogether for the entire schema, use a global binding setting like this (this is actually telling XJC not to generate enums if a simple type has more than 0 constants --- the net effect is no enum generation):

Avoid generating enums at all
<xs:schema ...>
  <xs:annotation><xs:appinfo>
    <jaxb:globalBindings typesafeEnumMaxMembers="0" />
  </xs:appinfo></xs:annotation>
  ...
</xs:schema>

1.7.2. Mapping to DOM

The<jaxb:dom>customization allows you to map a certain part of the schema into a DOM tree. This customization can be attached to the following schema components:

  • Wildcards (<xs:any>)
  • Type definitions (<xs:complexType> and <xs:simpleType>)
  • Model groups (<xs:choice>,<xs:all>,<xs:sequence>)
  • Model group declarations (<xs:group>)
  • Particles
  • Element declarations (<xs:element>)
In the following example, a wildcard is mapped to a DOM node. Each element that matches to the wildcard will be turned into a DOM tree.
Dom Customization example
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
               xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
               jaxb:version="2.0">

        <xs:element>
           <xs:complexType>
              <xs:sequence>
                 <xs:any maxOccurs="unbounded" processContents="skip">
                    <xs:annotation><xs:appinfo>
                      <jaxb:dom/>
                    </xs:appinfo></xs:annotation>
                 </xs:any>
              </xs:sequence>
           </xs:complexType>
        </xs:element>
    .
    .
    .
    </xs:schema>

This extension can be used to access wildcard content or can be used to process a part of a document by using other technologies that require "raw" XML. By default, JAXB generates a getContent() method for accessing wildcard content, but it only supports "lax" handling which means that unknown content is discarded. You may find more information in 7.12 chapter ofJAXB 2 specification.


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