Java - HyperJaxb - From Xml (Jaxb) to database (Jpa)

Data

From the XML Schema Primer, download the purchase order schema example:

• the xsd: po.xsd
• the sample data XML file: po.xml

Project Structure

Download the basic project templates for Ant (hyperjaxb3-ejb-template-basic-0.5.6-ant-src.zip)

Directory Structure

• Unpack the basic project templates and import it into an Eclipse Java project
• Add the content of the lib directory in your class path
• Put your schema (*.xsd) and binding files (*.xjb) into src/main/resources.
• Put your XML samples (*.xml) into src/test/samples.

Run the build

• Run mvn clean install for Maven or ant clean install for Ant.

ant clean install

Buildfile: D:\workspace\HyperJaxb2\build.xml

clean:

generate-sources:
    [mkdir] Created dir: D:\workspace\HyperJaxb2\target\generated-sources\xjc
      [xjc] Consider using <depends>/<produces> so that XJC won't do unnecessary compilation
      [xjc] Compiling file:/D:/workspace/HyperJaxb2/src/main/resources/po.xsd
      [xjc] Writing output to D:\workspace\HyperJaxb2\target\generated-sources\xjc

compile:
    [mkdir] Created dir: D:\workspace\HyperJaxb2\target\classes
    [javac] D:\workspace\HyperJaxb2\build.xml:142: warning: 'includeantruntime' was not set, default
ing to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 5 source files to D:\workspace\HyperJaxb2\target\classes
     [copy] Copying 3 files to D:\workspace\HyperJaxb2\target\classes

test-compile:
    [mkdir] Created dir: D:\workspace\HyperJaxb2\target\test-classes
    [javac] D:\workspace\HyperJaxb2\build.xml:158: warning: 'includeantruntime' was not set, default
ing to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 5 source files to D:\workspace\HyperJaxb2\target\test-classes
     [copy] Copying 3 files to D:\workspace\HyperJaxb2\target\test-classes

test:
    [mkdir] Created dir: D:\workspace\HyperJaxb2\target\junit-reports
    [junit] Running RoundtripTest
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 1.372 sec

package:
      [jar] Building jar: D:\workspace\HyperJaxb2\target\hyperjaxb3-ejb-template-basic-ant-0.5.6.jar


install:

BUILD SUCCESSFUL
Total time: 9 seconds

Check generated content

We got produced from the XJC schema compiler and Hyperjaxb3 plugin:

• a set of Java files containing both JAXB and JPA annotations.

The class contains @Entity, @Table, @ManyToOne and few other annotations generated by the Hyperjaxb3 plugin. These annotations turn this class into an entity which can be persisted with JPA.

• a JPA persistence unit description in META-INF/persistence.xml in target/generated-sources/xjc which contains the generated entities.

Persistence.xml:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persistence version="1.0" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
                        http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd
                        http://java.sun.com/xml/ns/persistence/orm
                        http://java.sun.com/xml/ns/persistence/orm_1_0.xsd" 
    xmlns="http://java.sun.com/xml/ns/persistence" 
    xmlns:orm="http://java.sun.com/xml/ns/persistence/orm" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <persistence-unit name="generated">
        <class>generated.Items</class>
        <class>generated.Items$Item</class>
        <class>generated.PurchaseOrderType</class>
        <class>generated.USAddress</class>
    </persistence-unit>
</persistence>

Jaxb

• Creation of an instance of JAXB context with a JAXBContext.newInstance(…) call passing the context path. The context path is typically the package name of the generated classes.

// Context with the package name of the generated class as parameter
context = JAXBContext.newInstance("generated");
// A context with the class name of the root element is also possible
context = JAXBContext.newInstance(PurchaseOrderType.class);

• Creation of the Unmarshaller which call an unmarshall action

// Creation of an Unmarshaller
final Unmarshaller unmarshaller = context.createUnmarshaller();
// The Unmarshaller unmarshal
final Object object = unmarshaller.unmarshal(new File("src/test/samples/po.xml"));

• Cast of the object to retrieve the good type and test

// With a cast, we retrieve the final object (data type)
@SuppressWarnings("unchecked")
final PurchaseOrderType purchaseOrder = ((JAXBElement<PurchaseOrderType>) object).getValue();
// Test
System.out.println("Purchase Order Comment "+purchaseOrder.getComment());

Jpa

Creation of an entity manager factory by passing:

• the name of persistence unit (see META-INF/persistence.xml above)
• a properties file (in the resource persistence.properties) to define the database-specific properties

You can define the database connection in the persistence unit itself but to keep ORM mappings should be generic, case-specific. They are be kept separately.

final Properties persistenceProperties = new Properties();
InputStream is = null;

try {
	is = getClass().getClassLoader().getResourceAsStream("persistence.properties");
	persistenceProperties.load(is);
} finally {
	if (is != null) {
		try {
			is.close();
		} catch (IOException ignored) {
		}
	}
}

entityManagerFactory = Persistence.createEntityManagerFactory(
		"generated", persistenceProperties);

persistence.properties

persistence.properties are database and JPA provider specific. See: JPA - Persistence Properties

Code

/**
 * 
 */
package main.java;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import generated.ObjectFactory;
import generated.PurchaseOrderType;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

/**
 * @author gerard
 *
 */
public class Main {

    private static JAXBContext context;
    private static EntityManagerFactory entityManagerFactory;
    
    /**
     * @param args
     * @throws JAXBException 
     * @throws IOException 
     */
    public static void main(String[] args) throws JAXBException, IOException {
	
	context = JAXBContext.newInstance("generated");
	new ObjectFactory();
	
	// Unmarshaller
	final Unmarshaller unmarshaller = context.createUnmarshaller();
	// Unmarshal
	final Object object = unmarshaller.unmarshal(new File("src/test/samples/po.xml"));
	// Cast
	@SuppressWarnings("unchecked")
	final PurchaseOrderType purchaseOrder = ((JAXBElement<PurchaseOrderType>) object).getValue();
	
	System.out.println("Purchase Order Comment "+purchaseOrder.getComment());
	
	final Properties persistenceProperties = new Properties();
	InputStream is = null;

	try {
		is = new FileInputStream("src/resources/persistence.properties");
		persistenceProperties.load(is);
	} finally {
		if (is != null) {
			is.close();		
		}
	}
	System.out.println("Url "+persistenceProperties.getProperty("hibernate.connection.url"));
	
	entityManagerFactory = Persistence.createEntityManagerFactory(
			"generated", persistenceProperties);
	
	final EntityManager saveManager = entityManagerFactory
		.createEntityManager();
	saveManager.getTransaction().begin();
	saveManager.persist(purchaseOrder);
	saveManager.getTransaction().commit();
	saveManager.close();
	
	final Long id = purchaseOrder.getHjid();
	System.out.println("Purchase Order Id "+id);

    }

}

javax.xml.bind.UnmarshalException: unexpected element (uri…

The fact that it doesn't unmarshal, is clear in the error message: it expects a no-namespace element <{}Repository> as opposed to <{uri:“http://www.oracle.com/obis/repository”}Repository>.

Exception in thread "main" javax.xml.bind.UnmarshalException: unexpected element (uri:"http://www.oracle.com/obis/repository", local:"BusinessModel"). Expected elements are <{}Repository>
	at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:662)