36.5. Customizing Fixed Value Attribute Mapping

Overview

By default, the code generators map attributes defined as having a fixed value to normal properties. When using schema validation, Apache CXF can enforce the schema definition (see Table 22.10, “Schema Validation Type Values”). However, using schema validation increases message processing time.
Another way to map attributes that have fixed values to Java is to map them to Java constants. You can instruct the code generator to map fixed value attributes to Java constants using the globalBindings customization element. You can also customize the mapping of fixed value attributes to Java constants at a more localized level using the property element.

Global customization

You can alter this behavior by adding the globalBinding element's fixedAttributeAsConstantProperty attribute. Setting this attribute to true instructs the code generator to map any attribute defined using fixed attribute to a Java constant.
Example 36.21, “in-Line Customization to Force Generation of Constants” shows an in-line customization that forces the code generator to generate constants for attributes with fixed values.

Example 36.21. in-Line Customization to Force Generation of Constants

<schema targetNamespace="http://widget.com/types/widgetTypes" 
        xmlns="http://www.w3.org/2001/XMLSchema" 
        xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
        xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
        jaxb:version="2.0">
  <annotation>
    <appinfo>
      <jaxb:globalBindings fixedAttributeAsConstantProperty="true" />
    </appinfo>
  </annotation>
  ...
</schema>
Example 36.22, “Binding File to Force Generation of Constants” shows an external binding file that customizes the generation of fixed attributes.

Example 36.22. Binding File to Force Generation of Constants

<jaxb:bindings xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
               jaxb:version="2.0">
  <jaxb:bindings schemaLocation="types.xsd">
    <jaxb:globalBindings fixedAttributeAsConstantProperty="true" />
  <jaxb:bindings>
<jaxb:bindings>

Local mapping

You can customize attribute mapping on a per-attribute basis using the property element's fixedAttributeAsConstantProperty attribute. Setting this attribute to true instructs the code generator to map any attribute defined using fixed attribute to a Java constant.
Example 36.23, “In-Line Customization to Force Generation of Constants” shows an in-line customization that forces the code generator to generate constants for a single attribute with a fixed value.

Example 36.23. In-Line Customization to Force Generation of Constants

<schema targetNamespace="http://widget.com/types/widgetTypes" 
        xmlns="http://www.w3.org/2001/XMLSchema" 
        xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
        xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
        jaxb:version="2.0">
  <complexType name="widgetAttr">
    <sequence>
      ...
    </sequence>
    <attribute name="fixer" type="xsd:int" fixed="7">
      <annotation>
        <appinfo>
          <jaxb:property fixedAttributeAsConstantProperty="true" />
        </appinfo>
      </annotation>
     </attribute>
  </complexType>
  ...
</schema>
Example 36.24, “Binding File to Force Generation of Constants” shows an external binding file that customizes the generation of a fixed attribute.

Example 36.24. Binding File to Force Generation of Constants

<jaxb:bindings xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
               jaxb:version="2.0">
  <jaxb:bindings schemaLocation="types.xsd">
    <jaxb:bindings node="xsd:complexType[@name='widgetAttr']">
      <jaxb:bindings node="xsd:attribute[@name='fixer']">
            <jaxb:property fixedAttributeAsConstantProperty="true" />
        </jaxb:bindings>
    </jaxb:bindings>
  </jaxb:bindings>
<jaxb:bindings>

Java mapping

In the default mapping, all attributes are mapped to standard Java properties with getter and setter methods. When this customization is applied to an attribute defined using the fixed attribute, the attribute is mapped to a Java constant, as shown in Example 36.25, “Mapping of a Fixed Value Attribute to a Java Constant”.

Example 36.25. Mapping of a Fixed Value Attribute to a Java Constant

@XmlAttribute
public final static type NAME = value;
type is determined by mapping the base type of the attribute to a Java type using the mappings described in Section 32.1, “Primitive Types”.
NAME is determined by converting the value of the attribute element's name attribute to all capital letters.
value is determined by the value of the attribute element's fixed attribute.
For example, the attribute defined in Example 36.23, “In-Line Customization to Force Generation of Constants” is mapped as shown in Example 36.26, “Fixed Value Attribute Mapped to a Java Constant”.

Example 36.26. Fixed Value Attribute Mapped to a Java Constant

@XmlRootElement(name = "widgetAttr")
public class WidgetAttr {

    ...

  @XmlAttribute
  public final static int FIXER = 7;

  ...

}