Question

Here’s a trivial excerpt from my XSD file

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="ns"
    xmlns:tns="sns" elementFormDefault="qualified">

  <element name="document">
        <attribute name="title" use="required"/>
  </element>
</schema>

I use the maven-jaxb2-plugin to generate Java classes from this. The Document class has a getTitle() method to return the text of the title attribute.

I want to add an additional method to Document:

public String getStrippedTitle() {
   return getTitle().replaceAll("\\s+", "");
}

I want my extra method to appear on the unmarshalled object (rather than me just calling it or writing a wrapper class) because I want to pass the top-level unmarshalled object off to a string template and have it iterate over sub-elements calling my extra method.

I found instructions but they tell me to set a property on the Unmarshaller and my (Mac OS X, Java 7) implementation doesn’t appear to support any properties.

How should I do this?

Answer 1

Following the link the Brian Henry gave, I found I could perform binding customization inline in my schema file to do what I wanted. The effect is exactly the same as Brian’s solution, but it doesn’t require a reference to a reference to com.sun.xml.internal.

First, the schema file gets modified somewhat:

<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="ns"
    xmlns:tns="sns" elementFormDefault="qualified"
    xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
jaxb:version="2.0">

  <element name="document">
      <annotation>
          <appinfo>
              <jaxb:class implClass="DocumentEx" />
          </appinfo>
      </annotation>
      <attribute name="title" use="required"/>
  </element>
</schema>

When the schema gets compiled into Java code, the generated ObjectFactory will refer to DocumentEx instead of Document. DocumentEx is a class I create, which looks like this:

public class DocumentEx extends Document {
   public String getStrippedTitle() {
       return getTitle().replaceAll("\\s+", "");
   }
}

Document (the class I’m extending) is still generated by the schema-to-Java compiler. Now when I unmarshall a document I actually get a DocumentEx object:

    JAXBContext jaxbContext = JAXBContext.newInstance("com.example.xml");
    Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
    unmarshaller.setSchema(testSchema);
    DocumentEx doc = (DocumentEx)unmarshaller.unmarshal(xmlFile);

There is some (hard-to-parse) documentation for this at Oracle and some helpful examples at O’Reilly.