How can I use factored-out .xsd files from a resource jar to specify a JAXB schema?

Question

I am unmarshalling an XML file into a JAXB-generated Java object. I would like the unmarshaller to validate the file against the schema in the process. The schema's .xsd file is inside a dependencies .jar file. I set the schema like so:

ClassLoader classLoader = getClass().getClassLoader();
InputStream schemaStream = classLoader.getResourceAsStream(schemaFilePath);
StreamSource schemaSource = new StreamSource(schemaStream);
Schema schema = factory.newSchema(schemaSource);
unmarshaller.setSchema(schema);

That mostly works except for one issue. The schema has some complex types factored out into other .xsd files. The unmarshaller doesn't appear to be able to find the factored-out .xsd files because when I attempt to set the schema I'm getting the SAXException:

Cannot resolve the name 'tns:FactoredOutType' to a(n) 'type definition' component.

Note: This works fine when running from eclipse, when it references the .xsd files from the target folder instead of from the .jar file.

Anybody have any ideas how I can get the factored-out .xsd files working for a schema that is in a dependency's .jar file?

Edit:

In case it's helpful information, the top-level .xsd is in a model folder, and the type it references is in model/common, so I reference the top-level .xsd as:

"model/TopLevel.xsd"

... and inside it, it references the factored-out .xsd as:

"common/FactoredOut.xsd"

Answer 1

I ended up fixing the issue by switching my call to newSchema from passing a StreamSource to passing a URL, which preserved the base URI so the included types could still be found (as @PetruGardea mentioned in his comment). The resulting code looks like this:

URL schemaURL = objectType.getClassLoader().getResource(schemaPath);
if (schemaURL != null) {
    Schema schema = factory.newSchema(schemaURL);
    unmarshaller.setSchema(schema);
}

Thank you all for your help!

Answer 2

We have a number XSDs that import/include others. We get this to work by passing them all to the SchemaFactory explicitly, rather than relying on the import to work and find it on the classpath. Here is what the code looks like:

    try (InputStream xsdStream0 = ClaimLoadService.class.getResourceAsStream("/a.xsd");
            InputStream xsdStream1 = ClaimLoadService.class.getResourceAsStream("/b.xsd");
            InputStream xsdStream2 = ClaimLoadService.class.getResourceAsStream("/c.xsd");
            InputStream xsdStream3 = ClaimLoadService.class.getResourceAsStream("/d.xsd");
            InputStream xsdStream4 = ClaimLoadService.class.getResourceAsStream("/e.xsd");) {
        SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        schema = sf.newSchema(new Source[] { new StreamSource(xsdStream0), new StreamSource(xsdStream1),
                new StreamSource(xsdStream2), new StreamSource(xsdStream3), new StreamSource(xsdStream4) });
        ...
    } catch (SAXException | IOException | JAXBException e) {
        logger.log(Level.INFO, e.getMessage(), e);
    }

Another thing that we sometimes have to do in order to make JAXB entirely happy is to ensure that the importing schema actually references the imported types. I don't recall the exact error that indicates we need to do the workaround, but perhaps this is what you are hitting. It is cheesy, but we do this as a workaround:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns="http://blah" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:name="http://blahblah" targetNamespace="http://blah"
elementFormDefault="qualified">

    <xs:import namespace="http://blahblah" />

    ...

    <xs:element name="ReferencesToMakeTheseElementsVisibleToThisJaxbContext">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="Business" type="name:type" minOccurs="0" />
                ...
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>

Basically, we create a complexType just for the purpose of explicitly referencing some of the imported types. We only have to do this when the type is not otherwise directly referenced.

Answer 3

Usually, the XML-related APIs have one means to allow the programmer specify location of auxiliary files which is called resource resolution. In the case of Schema, I think you must implement a LSResourceResolver and pass it to SchemaFactory.setResourceResolver before invoking newSchema.