org.eclipse.persistence.sdo.helper.jaxb
Class JAXBHelperContext

java.lang.Object
  org.eclipse.persistence.sdo.helper.SDOHelperContext
      org.eclipse.persistence.sdo.helper.jaxb.JAXBHelperContext

All Implemented Interfaces:

commonj.sdo.helper.HelperContext

public class JAXBHelperContext
extends SDOHelperContext

The JAXBHelperContext is a bridge between POJOs and SDO DataObjects. The bridge is based on their corresponding XML representations. For the POJOs the XML representation is specified using JAXB annotations or object-to-XML mappings.

The following steps are required to create the JAXBHelperContext. The XML schema used in step #3 is the same one that the POJOs are mapped to. This step has been separated so that SDO annotations could be added to the XML schema.

Step #1 - Create the JAXBContext

 JAXBContext jaxbContext = JAXBContext.newInstance("com.example.customer");
 

Step #2 - Create the JAXBHelperContext

 JAXBHelperContext jaxbHelperContext = new JAXBHelperContext(jaxbContext);
 

Step #3 - Create the SDO Metadata from an XML Schema

 jaxbHelperContext.getXSDHelper().define(xmlSchema);
 

The JAXBHelperContext allows you to convert between POJOs and DataObjects using a wrap operation.

 Customer customer = new Customer();
 Address address new Address();
 address.setStreet("123 Any Street");
 customer.set(address);
 
 DataObject customerDO = jaxbHelperContext.wrap(customer);
 customerDO.getString("address/street");  // returns "123 Any Street"
 

The JAXBHelperContext allows you to convert between DataObjects and POJOs using an unwrap operation.

 Type customerType = jaxbHelperContext.getType(Customer.class);
 DataObject customerDO = jaxbHelperContext.getDataFactory().create(customerType);
 customerDO.set("first-name", "Jane");
 
 Customer customer = jaxbHelperContext.unwrap(customerDO);
 customer.getFirstName();  // returns "Jane"
 

Of course the POJOs may be JPA entities. Below is an example of wrapping the results of a JPA query.

 EntityManagerFactory emf = Persistence.createEntityManagerFactory("CustomerExample");      
 EntityManager em = emf.createEntityManager();
 List entities = em.createQuery("SELECT e FROM MyEntity e WHERE ...").getResultList();
 List dataObjects = hc.wrap(entities);
 

Constructor Summary

JAXBHelperContext(JAXBContext aJAXBContext)
Create a new instance of JAXBHelperContext

JAXBHelperContext(JAXBContext aJAXBContext, ClassLoader aClassLoader)
Create a new instance of JAXBHelperContext

Method Summary

Class	getClass(commonj.sdo.Type type) Return the wrapped class corresponding to the SDO type.
JAXBContext	getJAXBContext() Return the JAXBContext.
commonj.sdo.Type	getType(Class entityClass) Return the SDO type corresponding to the wrapped class.
List<Object>	unwrap(Collection<commonj.sdo.DataObject> dataObjects) Perform the unwrap operation on each of the DataObjects in the collection, and return the results as a List.
Object	unwrap(commonj.sdo.DataObject dataObject) Return the POJO that is wrapped by the DataObject.
List<commonj.sdo.DataObject>	wrap(Collection<Object> entities) Perform the wrap operation on each of the POJOs in the collection, and return the results as a List.
commonj.sdo.DataObject	wrap(Object entity) Return a DataObject that wraps a POJO.

Methods inherited from class org.eclipse.persistence.sdo.helper.SDOHelperContext

createResolvable, createResolvable, getCopyHelper, getDataFactory, getDataHelper, getEqualityHelper, getHelperContext, getHelperContext, getHelperContext, getIdentifier, getTypeHelper, getXMLHelper, getXSDHelper, makeDefaultContext, putHelperContext, putHelperContext, removeHelperContext, removeHelperContext, reset

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JAXBHelperContext

public JAXBHelperContext(JAXBContext aJAXBContext)

Create a new instance of JAXBHelperContext

Parameters:

aJAXBContext - - The JAXBContext representing the class to XML schema mapping.

JAXBHelperContext

public JAXBHelperContext(JAXBContext aJAXBContext,
                         ClassLoader aClassLoader)

Create a new instance of JAXBHelperContext

Parameters:

aJAXBContext - - The JAXBContext representing the class to XML schema mapping.

aClassLoader - - The ClassLoader containing the generated SDO classes/interfaces (if any).

Method Detail

getJAXBContext

public JAXBContext getJAXBContext()

Return the JAXBContext. The JAXBContext represents the Java class to XML schema information for the POJOs.

getType

public commonj.sdo.Type getType(Class entityClass)

Return the SDO type corresponding to the wrapped class.

 Type customerType = jaxbHelperContext.getType(Customer.class);
 DataObject customerDO = jaxbHelperContext.getDataFactory().create(customerType);
 

getClass

public Class getClass(commonj.sdo.Type type)

Return the wrapped class corresponding to the SDO type.

 Type customerType = jaxbHelperContext.getTypeHelper().getType("urn:customer", "customer");
 Class customerClass = jaxbHelperContext.getClass(customerType);
 

wrap

public commonj.sdo.DataObject wrap(Object entity)

Return a DataObject that wraps a POJO. This call should be made on the root POJO.

 Customer customer = new Customer();
 Address address new Address();
 address.setStreet("123 Any Street");
 customer.set(address);
 
 DataObject customerDO = jaxbHelperContext.wrap(customer);
 customerDO.getString("address/street");  // returns "123 Any Street"
 

Multiple calls to wrap for the same instance POJO return the same instance of DataObject, in other words the following is always true:

 jaxbHelperContext.wrap(customer123) == jaxbHelperContext.wrap(customer123)
 jaxbHelperContext.wrap(customer123) != jaxbHelperContext.wrap(customer456)
 

wrap

public List<commonj.sdo.DataObject> wrap(Collection<Object> entities)

Perform the wrap operation on each of the POJOs in the collection, and return the results as a List.

unwrap

public Object unwrap(commonj.sdo.DataObject dataObject)

Return the POJO that is wrapped by the DataObject.

 Type customerType = jaxbHelperContext.getType(Customer.class);
 DataObject customerDO = jaxbHelperContext.getDataFactory().create(customerType);
 DataObject addressDO = customerDO.create("address");
 addressDO.set("street", "123 Any Street");
 
 Customer customer = (Customer) jaxbHelperContext.unwrap(customerDO);
 customer.getAddress().getStreet();  // returns "123 Any Street"
 

Multiple calls to unwrap for the same DataObject must return the same instance of Object, in other words the following is always true:

 jaxbHelperContext.unwrap(customerDO123) == jaxbHelperContext.unwrap(customerDO123)
 jaxbHelperContext.unwrap(customerDO123) != jaxbHelperContext.unwrap(customerDO456)
 customer123 == jaxbHelperContext.unwrap(jaxbHelperContext.wrap(customer123))
 

unwrap

public List<Object> unwrap(Collection<commonj.sdo.DataObject> dataObjects)

Perform the unwrap operation on each of the DataObjects in the collection, and return the results as a List.