Description David McCann 2010-08-12 13:12:03 EDT

A null pointer occurs when a transformation mapping is configured with a method name for that attribute transformer and a transformer class for the field transformer:

    XMLTransformationMapping mapping = new XMLTransformationMapping();
    mapping.setAttributeName("normalHours");
    mapping.setAttributeTransformation("myMethod");
    mapping.addFieldTransformer("start/text()", 
                                 new StartTransformer());      


The exception is:
___________________________________________________________________________

javax.xml.bind.JAXBException: 
Descriptor Exceptions: 
---------------------------------------------------------

Exception [EclipseLink-182] (Eclipse Persistence Services - 2.2.0.qualifier): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: The class, [org.example.StartTimeTransformer] cannot be used as a FieldTransformer.
Internal Exception: java.lang.NullPointerException
Mapping: org.eclipse.persistence.oxm.mappings.XMLTransformationMapping[normalHours]
Descriptor: XMLDescriptor(org.example.Employee --> [DatabaseTable(employee)])

Runtime Exceptions: 
---------------------------------------------------------

 - with linked exception:
[Exception [EclipseLink-0] (Eclipse Persistence Services - 2.2.0.qualifier): org.eclipse.persistence.exceptions.IntegrityException
Descriptor Exceptions: 
---------------------------------------------------------

Exception [EclipseLink-182] (Eclipse Persistence Services - 2.2.0.qualifier): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: The class, [org.example.StartTimeTransformer] cannot be used as a FieldTransformer.
Internal Exception: java.lang.NullPointerException
Mapping: org.eclipse.persistence.oxm.mappings.XMLTransformationMapping[normalHours]
Descriptor: XMLDescriptor(org.example.Employee --> [DatabaseTable(employee)])

Runtime Exceptions: 
---------------------------------------------------------
]
	at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:247)
	at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:207)
	at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:104)
	at org.eclipse.persistence.testing.jaxb.externalizedmetadata.ExternalizedMetadataTestCases.createContext(ExternalizedMetadataTestCases.java:576)
	at org.eclipse.persistence.testing.jaxb.externalizedmetadata.mappings.xmltransformation.XmlTransformationTestCases.testMethodSetOnType(XmlTransformationTestCases.java:147)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at junit.framework.TestCase.runTest(TestCase.java:168)
	at junit.framework.TestCase.runBare(TestCase.java:134)
	at junit.framework.TestResult$1.protect(TestResult.java:110)
	at junit.framework.TestResult.runProtected(TestResult.java:128)
	at junit.framework.TestResult.run(TestResult.java:113)
	at junit.framework.TestCase.run(TestCase.java:124)
	at junit.framework.TestSuite.runTest(TestSuite.java:232)
	at junit.framework.TestSuite.run(TestSuite.java:227)
	at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:79)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.2.0.qualifier): org.eclipse.persistence.exceptions.IntegrityException
Descriptor Exceptions: 
---------------------------------------------------------

Exception [EclipseLink-182] (Eclipse Persistence Services - 2.2.0.qualifier): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: The class, [org.example.StartTimeTransformer] cannot be used as a FieldTransformer.
Internal Exception: java.lang.NullPointerException
Mapping: org.eclipse.persistence.oxm.mappings.XMLTransformationMapping[normalHours]
Descriptor: XMLDescriptor(org.example.Employee --> [DatabaseTable(employee)])

Runtime Exceptions: 
---------------------------------------------------------

	at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:471)
	at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:406)
	at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.postConnectDatasource(DatabaseSessionImpl.java:667)
	at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.login(DatabaseSessionImpl.java:628)
	at org.eclipse.persistence.oxm.XMLContext.<init>(XMLContext.java:213)
	at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:336)
	at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:245)
	... 23 more

___________________________________________________________________________

The issue occurs due to the following check in the convertClassNamesToClasses method:

...
if (this.attributeTransformerClassName == null) {
    return;
}
...

This check prevents the field transformers from having their class names converted to classes if the attribute transformer class name is null (which it is in this case), which leads to the null pointer mentioned above.

One possible solution follows:

    public void convertClassNamesToClasses(ClassLoader classLoader){
        super.convertClassNamesToClasses(classLoader);

        if (this.attributeTransformerClassName != null) {
            Class attributeTransformerClass = null;
            try{
                if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
                    try {
                        attributeTransformerClass = (Class)AccessController.doPrivileged(new PrivilegedClassForName(attributeTransformerClassName, true, classLoader));
                    } catch (PrivilegedActionException exception) {
                        throw ValidationException.classNotFoundWhileConvertingClassNames(attributeTransformerClassName, exception.getException());
                    }
                } else {
                    attributeTransformerClass = org.eclipse.persistence.internal.security.PrivilegedAccessHelper.getClassForName(attributeTransformerClassName, true, classLoader);
                }
            } catch (ClassNotFoundException exc){
                throw ValidationException.classNotFoundWhileConvertingClassNames(attributeTransformerClassName, exc);
            }
            this.setAttributeTransformerClass(attributeTransformerClass);
        }
        
        for (Enumeration stream = getFieldTransformations().elements(); stream.hasMoreElements();) {
            FieldTransformation transformation = (FieldTransformation)stream.nextElement();
            if (transformation instanceof TransformerBasedFieldTransformation) {
                TransformerBasedFieldTransformation transformer = (TransformerBasedFieldTransformation)transformation;
                String transformerClassName = transformer.getTransformerClassName(); 
                if (transformerClassName == null) {
                    return;
                }
                Class transformerClass = null;
                try{
                    if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
                        try {
                            transformerClass = (Class)AccessController.doPrivileged(new PrivilegedClassForName(transformerClassName, true, classLoader));
                        } catch (PrivilegedActionException exception) {
                            throw ValidationException.classNotFoundWhileConvertingClassNames(transformerClassName, exception.getException());
                        }
                    } else {
                        transformerClass = org.eclipse.persistence.internal.security.PrivilegedAccessHelper.getClassForName(transformerClassName, true, classLoader);
                    }
                } catch (ClassNotFoundException exc){
                    throw ValidationException.classNotFoundWhileConvertingClassNames(transformerClassName, exc);
                }
                transformer.setTransformerClass(transformerClass);
            }
        }
    }

Note that this suggested change has not been fully tested.