Jaxb package-info ignored when using Java 10

I'm struggling with this, and any information would be greatly appreciated. I have a project that has been using JAXB for some time to construct a Java Model from an XML Schema and uses that model. This has been working in Java 8 for some tie now.

However, I've upgraded to Open JDK 10 and I get this error when I attempt to Unmarshall an XML file into the Java objects....

java.lang.IllegalArgumentException: javax.xml.bind.UnmarshalException: unexpected element (uri:"http://www.minestar.cat.com/namespace/units",
 local:"units"). Expected elements are <{}units>
        at minestar.units.schema.parser.UnitsXmlParser.readXml(UnitsXmlParser.java:31)
        at minestar.units.javagenerator.JavaGeneratorPlugin.execute(JavaGeneratorPlugin.java:41)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:154)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:146)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
        at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:956)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:290)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:194)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: javax.xml.bind.UnmarshalException: unexpected element (uri:"http://www.minestar.cat.com/namespace/units", local:"units"). Expected
 elements are <{}units>
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:741)
        at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:262)
        at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:257)
        at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportUnexpectedChildElement(Loader.java:124)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext$DefaultRootLoader.childElement(UnmarshallingContext.java:1149)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext._startElement(UnmarshallingContext.java:574)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.startElement(UnmarshallingContext.java:556)
        at com.sun.xml.bind.v2.runtime.unmarshaller.SAXConnector.startElement(SAXConnector.java:168)
        at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:509)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:374)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl$NSContentDriver.scanRootElementHook(XMLNSDocumentScanner
Impl.java:613)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScan
nerImpl.java:3058)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:821)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:602)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:112)
        at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:5
32)
        at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:888)
        at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:824)
        at java.xml/com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
        at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
        at java.xml/com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:635)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:258)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:229)
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:170)
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:209)
        at minestar.units.schema.parser.UnitsXmlParser.readXml(UnitsXmlParser.java:29)
        ... 23 more

I am using the maven-jaxb2-plugin to generate the sources, and they look fine. I have upgraded to the latest version of this plugin (at the time of this writing, 0.14.0). The classes are generated fine, and there is a package-info.java class generated and compiled into the resulting jar. The class in question looks like this at the top

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "dimensions",
    "quantityTypes"
})
@XmlRootElement(name = "units")
public class Units {

    @XmlElement(name = "dimension")
    protected List<Dimension> dimensions;
    @XmlElement(name = "quantityType")
    protected List<QuantityType> quantityTypes;

And the package-info.java looks like this

@javax.xml.bind.annotation.XmlSchema(namespace = "http://www.minestar.cat.com/namespace/units", elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)
package minestar.units.schema;

Because this is Java 10, I have added direct dependency entries to javax.xml.bind:jaxb-api:2.3.0, com.sun.xml.bind:jaxb-core:2.3.0 and com.sun.xml.bind:jaxb-impl:2.3.0.

I have tried changing JAXB implementation from the RI to Eclipse MOXy, but that made no difference.

As a test, I edited the generated Units.java class file above, adding the namespace attribute to the @XmlRootElement annotation...

@XmlRootElement(namespace = "http://www.minestar.cat.com/namespace/units", name = "units")
public class Units {

When this java file is compiled and used downstream, the XML file can be parsed. I do not receive the UnmarshalException. However, this source file is generated so I cannot rely on these changes staying put. Additionally, from everything that I have read from much more-informed people than myself, the package-info.class file (which is in the JAR file) should make the namespace value in the annotation unnecessary.

If there is something I have not set up correctly, I would be grateful for any assistance in getting this working in Java 10.

Thanks for any help, Ed

回答1:

I'm actually currently facing the same problem on Java 9.

Adding com.sun.xml.bind.backupWithParentNamespace system property makes it work, but I feel this is working around the problem.

I looked at the Java 9 source(have not looked at the Java 10 source yet), and it's inside the java.lang.Package.getPackageInfo() method that it tries to load the package-info class using:

...
String cn = packageName() + ".package-info";
Module module = module();
...
c = loader.loadClass(module, cn);
...

If I substitute it with

...
c = loader.loadClass(cn);
...

it manages to load it fine and all is well.

To me it looks like a JDK bug.

The latest maven-jaxb2-plugin does have the following option to turn off package-level annotations:

<packageLevelAnnotations>false</packageLevelAnnotations>

This resolved my problem.

Other XJC plugins seems to use "-npa" argument to turn off package-level annotations

回答2:

I have found the following solution for the same issue in my project with JDK 9:

    JAXBContext ctx = JAXBContext.newInstance(YOUR_CLASS.class);
    Unmarshaller unmarshaller = ctx.createUnmarshaller();
    SAXParserFactory sax = SAXParserFactory.newInstance();
    sax.setNamespaceAware(false); // This line is important!
    XMLReader reader = sax.newSAXParser().getXMLReader();
    Source source = new SAXSource(reader, new InputSource(new StringReader(xml)));
    return (YOUR_CLASS) unmarshaller.unmarshal(source);