Java XML Schema validation - ResourceResolver trouble
I am trying to build a component into a web application that will validate different XML documents against a set of schemas.
I have the validator class in java package com.example.xml and then I have a "package" for the schemas com.example.xml.Schemas where they are organized according to the namespace along with any included schemas, like so:
com.example.xml/SchemaValidator.java
com.example.xml.Schemas/2008/07/05/Message.xsd
com.example.xml.Schemas/2008/07/05/Person.xsd
com.example.xml.Schemas/2008/07/05/Address.xsd
com.example.xml.Schemas/2010/09/21/Message.xsd
com.example.xml.Schemas/2010/09/21/Organization.xsd
com.example.xml.Schemas/2010/09/21/Person.xsd
com.example.xml.Schemas/2010/09/21/Address.xsd
So most of the document-elements are called Message but in different namespaces and different internals. Via a mapping I can determine where the correct schema is located, and then I load the XSD matching the root element name - but to make the parser able to read the included schemas, I made an attempt at an org.w3c.dom.ls.LSResourceResolver implementation to fetch the correct files based on the systemId.
public class ResourceResolver implements LSResourceResolver {
private String basePath;
public ResourceResolver( String baseDirectory ){
basePath = baseDirectory;
if( !basePath.endsWith("/")){
basePath += "/";
}
}
@Override
public LSInput resolveResource(String type, String namespaceURI, String publicId, String systemId, String baseURI) {
System.out.println("Resolving: " + type + ", " + namespaceURI + ", " + publicId + ", " + systemId + ", " + baseURI + " (basepath:" + basePath + ")");
String mypath = basePath + systemId;
InputStream resourceAsStream = getClass().getResourceAsStream(mypath);
if( resourceAsStream == null){ System.out.println("Ups! Stream is null"); }
String contents = null;
byte[] bytes = null;
try {
bytes = new byte[resourceAsStream.available()];
resourceAsStream.read(bytes);
contents = new String(bytes, Charset.forName("UTF-8"));
} catch (IOException e) { }
finally{
try { resourceAsStream.close(); }
catch (IOException e) { }
}
Input xmlInput = new Input(resourceAsStream, type, namespaceURI, publicId, systemId, basePath);
xmlInput.setStringData(contents); // avoid problems with inputstream position
return xmlInput;
}
}
And my ResourceResolver is used this way:
public boolean validate(Document doc, String xsdPath) throws SAXException, IOException, ParserConfigurationException {
SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
String rootElmtName = doc.getDocumentElement().getLocalName();
String resourcePath = "/com/example/xml/" + xsdPath ;
InputStream topSchema = getClass().getResourceAsStream(xsdPath + "/" + rootElmtName + ".xsd");
Source schemaSource = new StreamSource(topSchema);
ResourceResolver resolver = new ResourceResolver(resourcePath);
schemaFactory.setResourceResolver(resolver);
Schema schema = schemaFactory.newSchema(schemaSource);
Validator validator = schema.newValidator();
validator.setResourceResolver(resolver);
Source source = new DOMSource(doc);
ValidationErrorHandler handler = new ValidationErrorHandler();
validator.setErrorHandler(handler);
validator.validate(source);
if(handler.hasErrors()){
for( ValidationError e : handler.getErrors()){
log(e);
}
return false;
}
return true;
}
However, it doesn't work! It resolves a few schema resources and then stops I tried setting a breakpoint in Eclipse in my resource resolver, and the inputstream is not null - it points to the right file containing a XSD. So something in the Java XML parser classes must expect some other behavior from my resolver.
Resolving: http://www.w3.org/2001/XMLSchema, http://com/example/xml/schemas/2005/08/07/, null, Letters.xsd, file:///com/example/xml/Schemas/2005/08/07/Message.xsd (basepath:/com/example/xml/Schemas/2005/08/07/)
Resolving: http://www.w3.org/2001/XMLSchema, http://com/example/xml/schemas/2005/08/07/, null, GeneralElements.xsd, file:///com/example/xml/Schemas/2005/08/07/Message.xsd (basepath:/com/example/xml/Schemas/2005/08/07/)
Resolving: http://www.w3.org/2001/XMLSchema, http://com/example/xml/schemas/2005/08/07/, null, GeneralTypes.xsd, file:///com/example/xml/Schemas/2005/08/07/Message.xsd (basepath:/com/example/xml/Schemas/2005/08/07/)
Exception in thread "main" org.xml.sax.SAXParseException: src-resolve: Cannot resolve the name 'Letters' to a(n) 'group' component.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:195)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:131)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:384)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.reportSchemaErr(XSDHandler.java:2537)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.reportSchemaError(XSDHandler.java:2528)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.getGlobalDecl(XSDHandler.java:1472)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDGroupTraverser.traverseLocal(XSDGroupTraverser.java:72)
The contents of the Message.xsd contains a bit like this:
<xs:include schemaLocation="Letters.xsd"/>
<xs:include schemaLocation="GeneralElements.xsd"/>
<xs:include schemaLocation="GeneralTypes.xsd"/>
<xs:element name="Message">
-and the Letters.xsd also contains
<xs:include schemaLocation="GeneralElements.xsd"/>
<xs:include schemaLocation="GeneralTypes.xsd"/>
<xs:group name="Letters">
The outline is of the ResourceResolver and Input classes are from another SO post - so I might have misunderstood something.
Is it the proper way I have created the resource resolver, or have I missed something completely?
