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Difference between revisions of "EclipseLink/UserGuide/MOXy/Runtime/XML MetadataSource"

Line 53: Line 53:
  
 
JAXBContext xmlBindingsContext = JAXBContext.newInstance("org.eclipse.persistence.jaxb.xmlmodel");
 
JAXBContext xmlBindingsContext = JAXBContext.newInstance("org.eclipse.persistence.jaxb.xmlmodel");
−
FileReader bindingsFile = new FileReader("moxy-bindings.xml");
+
FileReader bindingsFile = new FileReader("xml-bindings.xml");
 
XmlBindings bindings = (XmlBindings) xmlBindingsContext.createUnmarshaller().unmarshal(bindingsFile);
 
XmlBindings bindings = (XmlBindings) xmlBindingsContext.createUnmarshaller().unmarshal(bindingsFile);
 
</source>
 
</source>
Line 81: Line 81:
  
 
   private final String XML_BINDINGS_PACKAGE = "org.eclipse.persistence.jaxb.xmlmodel";
 
   private final String XML_BINDINGS_PACKAGE = "org.eclipse.persistence.jaxb.xmlmodel";
−
   private final String METADATA_URL = "http://www.example.com/private/metadata/moxy-bindings.xml";
+
   private final String METADATA_URL = "http://www.example.com/private/metadata/xml-bindings.xml";
  
 
   public MyMetadataSource() {
 
   public MyMetadataSource() {

Revision as of 15:00, 7 July 2011

EclipseLink MOXy

XML MetadataSource

EclipseLink 2.3 introduces the concept of a MetadataSource, which is responsible for serving up EclipseLink metadata. This allows you to store mapping information outside of your application and have it retrieved when the application's JAXBContext is being created or refreshed.


Implementing a MetadataSource

To implement your own MetadataSource, you can:

  • Create a new class that implements the org.eclipse.persistence.jaxb.metadata.MetadataSource interface.
  • Create a new class that extends the org.eclipse.persistence.jaxb.metadata.MetadataSourceAdapter class. Using this method is preferred, as it will insulate you from future additions to the interface.


In either case, you will be responsible for implementing the following method: 

/**
 * Retrieve XmlBindings according to the JAXBContext bootstrapping information.
 *
 * @param properties - The properties passed in to create the JAXBContext
 * @param classLoader - The ClassLoader passed in to create the JAXBContext
 * @return the XmlBindings object representing the metadata
 */
XmlBindings getXmlBindings(Map<String, ?> properties, ClassLoader classLoader);


XmlBindings

Internally, EclipseLink metadata is stored in an XmlBindings object, which itself is mapped with JAXB. This means that you can actually use a JAXB unmarshaller to read external metadata and create an XmlBindings from it: 

package example;
 
import org.eclipse.persistence.jaxb.xmlmodel.XmlBindings;
 
...
 
JAXBContext xmlBindingsContext = JAXBContext.newInstance("org.eclipse.persistence.jaxb.xmlmodel");
FileReader bindingsFile = new FileReader("xml-bindings.xml");
XmlBindings bindings = (XmlBindings) xmlBindingsContext.createUnmarshaller().unmarshal(bindingsFile);


Example

The following example creates an XmlBindings object by unmarshalling from a URL: 

package example;
 
import java.net.URL;
import java.util.Map;
 
import javax.xml.bind.JAXBContext;
 
import org.eclipse.persistence.jaxb.metadata.MetadataSourceAdapter;
import org.eclipse.persistence.jaxb.xmlmodel.XmlBindings;
 
public class MyMetadataSource extends MetadataSourceAdapter {
 
   private JAXBContext bindingsContext;
   private URL bindingsUrl;
 
   private final String XML_BINDINGS_PACKAGE = "org.eclipse.persistence.jaxb.xmlmodel";
   private final String METADATA_URL = "http://www.example.com/private/metadata/xml-bindings.xml";
 
   public MyMetadataSource() {
      try {
         bindingsContext = JAXBContext.newInstance(XML_BINDINGS_PACKAGE);
         bindingsUrl = new URL(METADATA_URL);
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
   }
 
   @Override
   public XmlBindings getXmlBindings(Map<String, ?> properties, ClassLoader classLoader) {
      try {
         Unmarshaller u = bindingsContext.createUnmarshaller();
         XmlBindings bindings = (XmlBindings) u.unmarshal(bindingsUrl);
         return bindings;
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
   }
 
}


Specifying the MetadataSource

To use a MetadataSource in creating a JAXBContext, add it to the properties map with the key JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY: 

MetadataSource metadataSource = new MyMetadataSourceImpl();
 
Map<String, Object> properties = new HashMap<String, Object>(1);
properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, metadataSource);
 
JAXBContext jc = JAXBContext.newInstance(new Class[] { Customer.class }, properties);
Retrieved from "https://wiki.eclipse.org/index.php?title=EclipseLink/UserGuide/MOXy/Runtime/XML_MetadataSource&oldid=260414"

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