EclipseLink/UserGuide/MOXy/Runtime/Bootstrapping/Single Project/From sessions.xml using DynamicEntities

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Dynamic Bootstrapping (Single Project) from sessions.xml (EclipseLink project)

With EclipseLink dynamic MOXy, you can bootstrapping from an EclipseLink project specified in sessions.xml file. In this scenario, your specifies only Java class names -- not the actual Java classes, as shown here:

CORRECT:

customerDescriptor.setJavaClassName("mynamespace.Customer");
...
addressMapping.setReferenceClassName("mynamespace.Address");

INCORRECT: <sorce lang="java"> customerDescriptor.setJavaClass(mynamespace.Customer.class); ... addressMapping.setReferenceClass(mynamespace.Address.class); </source>

You map these "imaginary" classes to XML. EclipseLink dynamically generates the classes in memory, when buildingn the DynamicJAXBContext.

Add your EclipseLink project to the EclipseLink sessions.xml file. Use the following API to pass the session's name to the DynamicJAXBContextFactory and create your DynamicJAXBContext:

/**
 * Create a <tt>DynamicJAXBContext</tt>, using an EclipseLink <tt>sessions.xml</tt> as the metadata source.
 * The <tt>sessionNames</tt> parameter is a colon-delimited list of session names within the
 * <tt>sessions.xml</tt> file.  <tt>Descriptors</tt> in this session's <tt>Project</tt> must <i>not</i>
 * have <tt>javaClass</tt> set, but <i>must</i> have <tt>javaClassName</tt> set.
 *
 * @param sessionNames
 *      A colon-delimited <tt>String</tt> specifying the session names from the <tt>sessions.xml</tt> file.
 * @param classLoader
 *      The application's current class loader, which will be used to first lookup
 *      classes to see if they exist before new <tt>DynamicTypes</tt> are generated.  Can be
 *      <tt>null</tt>, in which case <tt>Thread.currentThread().getContextClassLoader()</tt> will be used.
 * @param properties
 *      Map of properties to use when creating a new <tt>DynamicJAXBContext</tt>.  Can be null.
 *
 * @return
 *      A new instance of <tt>DynamicJAXBContext</tt>.
 *
 * @throws JAXBException
 *      if an error was encountered while creating the <tt>DynamicJAXBContext</tt>.
 */
public static DynamicJAXBContext createContext(String sessionNames, ClassLoader classLoader, 
   Map<String, ?> properties) throws JAXBException

Example

This example shows an EclipseLink MOXy project in code. Notice that:

• The package name of the generated classes will be com.mypackage.
  • If you were importing from an XSD, you would have used the default namespace to build the package, resulting in mynamespace instead.
• The first-name element in XML will be mapped to the fName field in Java
  • If you were importing from an XSD, the generated field name would have been firstName.
• A null address will be represented by xsi:nil="true" in XML.

package mynamespace;
 
import org.eclipse.persistence.oxm.NamespaceResolver;
import org.eclipse.persistence.oxm.XMLConstants;
import org.eclipse.persistence.oxm.XMLDescriptor;
 
import org.eclipse.persistence.oxm.mappings.XMLDirectMapping;
import org.eclipse.persistence.oxm.mappings.XMLCompositeObjectMapping;
 
public class CustomerProject extends org.eclipse.persistence.sessions.Project {
 
   public CustomerProject() {
      super();
 
      NamespaceResolver nsResolver = new NamespaceResolver();
      nsResolver.put("ns0", "mynamespace");
      nsResolver.put("xsi", XMLConstants.SCHEMA_INSTANCE_URL);
 
      XMLDescriptor customerDescriptor = new XMLDescriptor();
      customerDescriptor.setJavaClassName("mynamespace.Customer");
      customerDescriptor.setDefaultRootElement("customer");
      customerDescriptor.setNamespaceResolver(nsResolver);
 
      XMLDirectMapping firstNameMapping = new XMLDirectMapping();
      firstNameMapping.setAttributeName("fName");
      firstNameMapping.setXPath("first-name/text()");
      customerDescriptor.addMapping(firstNameMapping);
      // ...
 
      XMLCompositeObjectMapping addressMapping = new XMLCompositeObjectMapping();
      addressMapping.setAttributeName("address");
      addressMapping.setXPath("address");
      addressMapping.setReferenceClassName("mynamespace.Address");
      addressMapping.getNullPolicy().setNullRepresentedByXsiNil(true);
      addressMapping.getNullPolicy().setMarshalNullRepresentation(XMLNullRepresentationType.XSI_NIL);
      customerDescriptor.addMapping(addressMapping);
 
      XMLDescriptor addressDescriptor = new XMLDescriptor();
      addressDescriptor.setJavaClassName("mynamespace.Address");
      // ...
 
      this.addDescriptor(customerDescriptor);
      this.addDescriptor(addressDescriptor);
   }
 
}

Here is the 'sessions.xml that includes the project:

<?xml version="1.0" encoding="US-ASCII"?>
<sessions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ...>
   <session xsi:type="database-session">
      <name>MyCustomerProject</name>
      <primary-project xsi:type="class">mynamespace.CustomerProject</primary-project>
   </session>
</sessions>

Now, you instantiate a DynamicJAXBContext using the session name and begin working with the DynamicEntities:

DynamicJAXBContext dContext = DynamicJAXBContextFactory.createContext("MyCustomerProject", null, null);
 
DynamicEntity newCustomer = dContext.newDynamicEntity("com.mypackage.Customer");
newCustomer.set("fName", "Bob");
...
dContext.createMarshaller().marshal(newCustomer, System.out);

You can specify multiple Session names when bootstrapping from an EclipseLink project, by using:

DynamicJAXBContextFactory.createContext("ProjectA:ProjectB", null, null);

This creates a single DynamicJAXBContext that is aware of Mappings and Descriptors from both Projects.

Version: 2.2.0 DRAFT
Other versions...

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