It's excellent and it builds all Java classes from DB Schema.
Here some info on how to handle entities in JPA:
http://www.oracle.com/technology/products/ias/toplink/jpa/howto/create-modify-delete.html
If you want to ose other tools (not recommended)
Download:
http://www.oracle.com/technology/products/ias/toplink/index.html
Tutorial standalone:
http://www.oracle.com/technology/products/ias/toplink/doc/11110/tutorial/intro/standalone/intro_tutorial.htm
Run Workbench :
C:\apps\toplink_111130_en\utils\workbench\workbench.cmd
Unfortunately Workbench is not JPA aware.
This http://download.oracle.com/docs/cd/E13224_01/wlw/docs103/guide/ormworkbench/conGeneratingEJB3Mappings.html#creating_mappings_from_schema will explain you how to generate the JPA annotated Java classes from an existing database schema.
This is a JDeveloper demo on JPA
http://www.oracle.com/technology/products/jdev/viewlets/1013/ejb_30_viewlet_swf.html
An interesting JPA plugin for Eclipse (99 USD)
http://objectgeneration.com/eclipse/index.html
EclipseLink gives you JPA in Eclipse
http://wiki.eclipse.org/EclipseLink
Now let's setup a standalone application; I am using a schema SCOTT with username SCOTT and password TIGER on my local machine
CREATE TABLE test_entity (
entity_id NUMBER(10),
entity_name VARCHAR2(30),
entity_description VARCHAR2(50)
);
The JPA entity class:
package my.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.Table;
import javax.persistence.Column;
import javax.persistence.Id;
/** JPA Annotation linking DB table to Java Class. */
@Entity
@Table(name = "TEST_ENTITY", schema = "SCOTT")
public class TestEntity implements Serializable {
/** The Constant serialVersionUID. */
private static final long serialVersionUID = 1L;
/** The testEntity id. */
@Id
@Column(name = "ENTITY_ID")
private int entityId;
/** The testEntity name. */
@Column(name = "ENTITY_NAME")
private String entityName;
/** The testEntity description. */
@Column(name = "ENTITY_DESCRIPTION")
private String entityDescription;
/**
* Instantiates a new testEntity.
*/
public TestEntity() {}
/**
* Setter for the testEntity variable.
*
* @param entityId - the new value
*/
public void setTestEntityId(int entityId) {
this.entityId = entityId;
}
/**
* Getter for the testEntity variable.
*
* @return int
*/
public int getEntityId() {
return entityId;
}
/**
* Setter for the entityName variable.
*
* @param entityName - the new value
*/
public void setEntityName(String entityName) {
this.entityName = entityName;
}
/**
* Getter for entityName variable.
*
* @return String
*/
public String getEntityName() {
return entityName;
}
/**
* Setter for entityDescription variable.
*
* @param entityDescription - the new value
*/
public void setEntityDescription(String entityDescription) {
this.entityDescription = entityDescription;
}
/**
* Gettter for entityDescription variable.
*
* @return String
*/
public String getEntityDescription() {
return entityDescription;
}
}
use these jars:
commons-logging-api.jar
commons-logging.jar
odbc14.jar
toplink-essentials.jar
the persistence.xml should be:
oracle.toplink.essentials.PersistenceProvider jdbc/localXE my.entity.TestEntity
and this is the test client:
package my.entity;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityNotFoundException;
import javax.persistence.Persistence;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class TestEntityHandler implements Serializable {
/** Default Serial Version UID. */
private static final long serialVersionUID = 1L;
/** The Default Class LOGGER. */
private static final Log LOGGER = LogFactory.getFactory().getInstance(
TestEntityHandler.class.getName());
/** The entity manager factory. */
private static EntityManagerFactory entityManagerFactory = null;
/** The Entity Manager for JAXB container managed persistence. */
protected EntityManager em = null;
/** The testEntity. */
private TestEntity testEntity = null;
/**
* Public constructor.
*/
public TestEntityHandler() { testEntity = new TestEntity(); }
/**
* Initialise and return the JAXB EntityManager to be used by this Class instance.
*
* @return - a valid [initialised] EntityManager instance
*/
private EntityManager initialiseEntityManager() {
try {
if (em == null) {
em = getEntityManager();
LOGGER.info("Initialised Entity Manager: " + em);
}
} catch (Exception e) {
LOGGER.error("Failed to initialise EntityManager instance! ... " + e, e);
}
return em;
}
/**
* Persist a new instance of the Entity.
*/
public void create() {
initialiseEntityManager();
em.getTransaction().begin();
em.persist(testEntity);
em.getTransaction().commit();
//em.close();
}
/**
* Persist updated details of an existing instance of the Entity.
*/
public void update() {
initialiseEntityManager();
em.getTransaction().begin();
em.merge(testEntity);
em.getTransaction().commit();
// This next step should not be necessary; but sometimes update is not propagated !??
em.getTransaction().begin();
refreshEntity(testEntity);
em.getTransaction().commit();
//em.close();
}
/**
* Delete an existing instance of the Entity from the system.
*/
public void delete() {
initialiseEntityManager();
em.getTransaction().begin();
em.remove(testEntity);
em.getTransaction().commit();
//em.close();
}
/**
* Gets the testEntity.
*
* @return the testEntity
*/
public TestEntity getTestEntity() {
return testEntity;
}
/**
* Sets the testEntity.
*
* @param testEntity_ the new testEntity
*/
public void setTestEntity(TestEntity testEntity_) {
this.testEntity = testEntity_;
}
// Everything below belongs in other Class(es), reproduced here for simplicity.
/**
* Gets the entity manager.
*
* @return the entity manager
*/
private EntityManager getEntityManager () {
try {
if (entityManagerFactory == null) {
LOGGER.info("Attempting to create EntityManger ... ");
Map override = new HashMap();
// Override the provider used for persistence
override.put("provider", "oracle.toplink.essentials.PersistenceProvider");
// This name must correspond to value in META-INF/persistence.xml
entityManagerFactory = Persistence.createEntityManagerFactory("myPersistenceUnit");
}
EntityManager entityManager = null;
entityManager = entityManagerFactory.createEntityManager();
LOGGER.info("Returning EntityManger instance:= " + entityManager);
return entityManager;
} catch (Exception e) {
LOGGER.error("Exception in PersistenceManager.getEntityManager: " + e, e);
}
return null;
}
/**
* Refresh the entity from database.
*
* @param TestEntity - abstract class (substituted at runtime) that is to be refreshed
*/
protected void refreshEntity(TestEntity testEntity) {
try {
em.refresh(testEntity);
} catch(EntityNotFoundException ex){
LOGGER.debug("Failed to refresh entity; this may not be a problem");
}
}
/**
* Close the EntityManager instance.
*/
public void closeEM() {
em.close();
}
public static void main(String args[]) {
TestEntityHandler testEntityHandler = new TestEntityHandler();
TestEntity testEntity = new TestEntity();
testEntity.setTestEntityId(500);
testEntity.setEntityName("PierreLuigi");
testEntity.setEntityDescription("This is a test");
testEntityHandler.setTestEntity(testEntity);
testEntityHandler.create();
LOGGER.info("Created new TestEntity; check database now ... ");
try {
Thread.sleep(10000);
LOGGER.info("Resuming ... ");
} catch(InterruptedException e) {
e.printStackTrace();
}
// Before continuing check database to ensure that object was created.
testEntity.setEntityName("PierreLuigi Vernetto");
testEntityHandler.setTestEntity(testEntity);
testEntityHandler.getTestEntity().setEntityDescription("This is a second test (UPDATE)");
testEntityHandler.update();
LOGGER.info("Updated new TestEntity; check database now ... ");
try {
Thread.sleep(10000);
LOGGER.info("Resuming ... ");
} catch(InterruptedException e) {
e.printStackTrace();
}
// Before continuing check database to ensure that object was updated.
testEntity.setEntityName("Pierluigi Vernetto is stupid");
testEntity.setEntityDescription("This is a second test (UPDATE)");
testEntityHandler.delete();
LOGGER.info("Deleted new TestEntity.");
testEntityHandler.closeEM();
// Now check that the object was deleted.
}
}
