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Issues with EclipseLink MOXy OSGi bundle

I am working on a a very simple Eclipse Plug-in with which uses EclipseLink's MOXy for XML binding (marshalling/unmarshalling). I get a couple of errors when I try to marshall a simple class (Person.java) during the starting process of the plugin (Activator.java). Here's the code:

CODE:

Person.java

package test_rcp;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Person {

    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

}

Activator.java

package test_rcp;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;

import org.eclipse.ui.plugin.AbstractUIPlugin;
import org.osgi.framework.BundleContext;

public class Activator extends AbstractUIPlugin {

    public void start(BundleContext context) throws Exception {
        super.start(context);
        plugin = this;

        // Just to make sure EclipseLink is already loaded
        System.out.println(org.eclipse.persistence.Version.getVersion());

        Person p1 = new Person();
        p1.setName("John Dewey");
        p1.setAge(54);
        JAXBContext jc = JAXBContext.newInstance("test_rcp",Person.class.getClassLoader());

         Marshaller marshaller = jc.createMarshaller();
         marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
         marshaller.marshal(p1, System.out);
    }
}

MANIFEST.MF

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Test-RCP
Bundle-SymbolicName: Test-RCP; singleton:=true
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: test_rcp.Activator
Require-Bundle: org.eclipse.ui,
 org.eclipse.core.runtime,
 org.eclipse.persistence.core,
 org.eclipse.persistence.moxy;bundle-version="2.4.1"
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.7

The package test_rcp also contains jaxb.index and jaxb.properties:

jaxb.index

Person

jaxb.properties

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

PROBLEM:

Running the plug-in however throws the following exception:

javax.xml.bind.JAXBException: Provider org.eclipse.persistence.jaxb.JAXBContextFactory could not be instantiated: 
javax.xml.bind.JAXBException: Provider class org.eclipse.persistence.jaxb.JAXBContextFactory could not be instantiated:
 javax.xml.bind.JAXBException:
 ClassCastException: attempting to cast bundleresource://43.fwk583158213/javax/xml/bind/JAXBContext.class to jar:file:/usr/lib/jvm/java-7-oracle/jre/lib/rt.jar!/javax/xml/bind/JAXBContext.class.  Please make sure that you are specifying the proper ClassLoader.

I understand that the problem arises from the fact that two class loaders have loaded javax.xml.bind package, but I cannot figure out why and how to avoid this.

Morover, by using JAXBContextFactory instead of JAXBContext.newInstance(as suggested here), i.e.:

JAXBContext jc = org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(new Class[] {Person.class}, null);

I would get the following exception:

java.lang.LinkageError: loader constraint violation:
loader (instance of org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) previously
initiated loading for a different type with name "javax/xml/bind/JAXBContext"

I have already tried out following solutions with no success:

https://stackoverflow.com/a/12943115/2295964

https://stackoverflow.com/a/11797373/2295964

I would really appreciate if someone could help me getting out of this misery!

Solution

  • You need to ensure that you import the javax.xml.bind bundle instead of getting the JAXB APIs from the JRE.