Mapping Enums

Java enums can be mapped to XML using the @XmlEnum and @XmlEnumValue annotations.

Mapping Enums using Constant Names

The following schema demonstrates an XML enumeration:

Example 4-40 Sample XML Schema

<xs:simpleType name="CustomerType">
   <xs:restriction base="xs:string"/>
      <xs:enumeration value="PROMO_CUSTOMER"/>
      <xs:enumeration value="NEW_CUSTOMER"/>
      <xs:enumeration value="VIP"/>
      <xs:enumeration value="NORMAL"/>
   </xs:restriction>
</xs:simpleType>

If your enum constant names themselves are sufficient for the XML representation, you can simply use the @XmlEnum annotation:

Example 4-41 Using the @XmlEnum Annotation

package example;
 
import javax.xml.bind.annotation.*;
 
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {
   private CustomerType type = CustomerType.NEW_CUSTOMER;
 
   @XmlEnum(String.class)
   private enum CustomerType { PROMO_CUSTOMER, NEW_CUSTOMER, VIP, NORMAL }
 
   ...
}

Example 4-42 shows how to define this mapping in EclipseLink OXM Metadata:

Example 4-42 Sample XML Mapping

...
<xml-enums>
   <xml-enum java-enum="CustomerType" value="java.lang.String">
      <xml-enum-value java-enum-value="PROMO_CUSTOMER">PROMO_CUSTOMER</xml-enum-value>
      <xml-enum-value java-enum-value="NEW_CUSTOMER">NEW_CUSTOMER</xml-enum-value>
      <xml-enum-value java-enum-value="VIP">VIP</xml-enum-value>
      <xml-enum-value java-enum-value="NORMAL">NORMAL</xml-enum-value>
   </xml-enum>
</xml-enums>
 
<java-types>
   <java-type name="Customer">
      <xml-root-element name="customer"/>
      <java-attributes>
         <xml-element java-attribute="type" type="CustomerType"/>
      </java-attributes>
   </java-type>
</java-types>
...

When marshalled to XML, a Customer would look like this:

<customer>
   <type>NEW_CUSTOMER</type>
</customer>

Mapping Enums to Custom XML Values

Given the following XML schema enumeration:

Example 4-43 Sample XML Schema

<xs:simpleType name="CustomerType">
   <xs:restriction base="xs:int">
      <xs:enumeration value="1"/>
      <xs:enumeration value="2"/>
      <xs:enumeration value="3"/>
      <xs:enumeration value="4"/>
   </xs:restriction>
</xs:simpleType>

To model this in Java, the @XmlEnumValue annotation is used to provide an XML value for each enum constant:

Example 4-44 Using the @XmlEnumValue Annotation

package example;
 
import javax.xml.bind.annotation.*;
 
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {
 
   private CustomerType type = CustomerType.NEW_CUSTOMER;
 
   @XmlEnum(Integer.class)
   private enum CustomerType { 
      @XmlEnumValue("1") PROMO_CUSTOMER, 
      @XmlEnumValue("2") NEW_CUSTOMER, 
      @XmlEnumValue("3") VIP,
      @XmlEnumValue("4") NORMAL;
 
      ...
}

Example 4-45 shows how to define this mapping in EclipseLink OXM Metadata:

Example 4-45 Sample XML Mapping

...
<xml-enums>
   <xml-enum java-enum="CustomerType" value="java.lang.Integer">
      <xml-enum-value java-enum-value="PROMO_CUSTOMER">1</xml-enum-value>
      <xml-enum-value java-enum-value="NEW_CUSTOMER">2</xml-enum-value>
      <xml-enum-value java-enum-value="VIP">3</xml-enum-value>
      <xml-enum-value java-enum-value="NORMAL">4</xml-enum-value>
   </xml-enum>
</xml-enums>
 
<java-types>
   <java-type name="Customer">
      <xml-root-element name="customer"/>
      <java-attributes>
         <xml-element java-attribute="type" type="CustomerType"/>
      </java-attributes>
   </java-type>
</java-types>
...

When marshalled to XML, a new Customer would look like this:

<customer>
   <type>2</type>
</customer>