I am using JAXB to bind XML to Java for an application that I am writing. I have an element called measure which contains two amount elements called amount and maxAmount, with which I want to model a lower and an upper limiting value. amount and maxAmount are otherwise identical and I would like them to be implemented with the same class when unmarshalled into Java.
The following is an extract from the XML schema which I feed to JAXB:
<xsd:attributeGroup name="AmountAttributes">
<xsd:attribute name="quantity" type="xsd:decimal"/>
<xsd:attribute name="numerator" type="xsd:nonNegativeInteger"/>
<xsd:attribute name="denominator" type="xsd:positiveInteger"/>
</xsd:attributeGroup>
<xsd:element name="measure">
<xsd:complexType>
<xsd:sequence>
<xsd:element minOccurs="0" name="amount">
<xsd:complexType>
<xsd:attributeGroup ref="mpr:AmountAttributes"/>
</xsd:complexType>
</xsd:element>
<xsd:element minOccurs="0" name="maxAmount">
<xsd:complexType>
<xsd:attributeGroup ref="mpr:AmountAttributes"/>
</xsd:complexType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
JAXB creates from this a more elaborate version of the following:
public class Measure {
protected Measure.Amount amount;
protected Measure.MaxAmount maxAmount;
public static class Measure.Amount {}
public static class Measure.MaxAmount {}
}
Measure.Amount and Measure.MaxAmount are identical except for their names, but - of course - as far as Java is concerned they have little to do with each other.
Is there a way of making JAXB use the same class for both amount and maxAmount?
Just to come completely clean ;-) I should mention that I generate the XML schema from RNC using Trang. If the answer to the question is "change the XML schema", I have the supplementary question "how do I change the RNC to produce that XML schema?". My RNC looks like this:
AmountAttributes =
QuantityAttribute?
& attribute numerator { xsd:nonNegativeInteger }?
& attribute denominator { xsd:positiveInteger }?
QuantityAttribute = attribute quantity { xsd:decimal }
Measure =
element measure {
element amount { AmountAttributes }?,
element maxAmount { AmountAttributes }?
}+
I use RNC because I find it simpler to understand, but if the solution to my problem means just using XML Schema, so be it.
Steve
