Refreshing Metadata

Introduced in EclipseLink MOXy 2.3, you can refresh the JAXBContext metadata at runtime. This allows you to make changes to existing mappings in a live application environment and see those changes immediately without having to create a new JAXBContext.

In order to use the Metadata Refresh feature, your metadata information must be provided in one of the following formats:

• javax.xml.transform.Source

• org.w3c.dom.Node

• org.eclipse.persistence.jaxb.metadata.MetadataSource

<?xml version="1.0"?>
<xml-bindings
      xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="example">
    <java-types>
        <java-type name="Root">
            <java-attributes>
                <xml-element java-attribute="name" name="orig-name"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>
 

The JAXBContext is created in the standard way:

 
...
ClassLoader classLoader = ClassLoader.getSystemClassLoader();
 
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
DocumentBuilder db = dbf.newDocumentBuilder();
InputStream metadataStream = classLoader.getResourceAsStream("example/eclipselink-oxm.xml";
Document metadataDocument = db.parse(metadataStream);
metadataStream.close();
 
Map<String, Object> props = new HashMap<String, Object>(1);
props.put(JAXBContextProperties.OXM_METADATA_SOURCE, metadataDocument);
JAXBContext context = JAXBContextFactory.createContext(new Class[] { Root.class }, props);
...
 

At this point, if we were to marshal a Root object to XML, it would look like this:

<root>
    <orig-name>RootName</orig-name>
</root>
 

For this example, we will modify the metadata Document directly to change the XML name for the name field. We can then refresh the metadata using the refreshMetadata() API:

...
Element xmlElementElement = (Element) metadataDocument.getElementsByTagNameNS("http://www.eclipse.org/eclipselink/xsds/persistence/oxm", "xml-element").item(0);
xmlElementElement.setAttribute("name", "new-name");
JAXBHelper.getJAXBContext(jc).refreshMetadata();
...
 

After refreshing metadata, the same Root object will be marshalled as follows:

<root>
      <new-name>RootName</new-name>
</root>