Validating against a Schema with JAXB
- by fwgx
I've been looking for solutions to this problem for far too long considering how easy it sounds so I've come for some help.
I have an XML Schema which I have used with xjc to create my JAXB binding. This works fine when the XML is well formed. Unfortunately it also doesn't complain when the XML is not well formed. I cannot figure out how to do proper full validation against the schema when I try to unmarshall an XML file.
I have managed to use a ValidationEventCollector to handle events, which works for XML parsing errors such as mismatched tags but doesn't raise any events when there is a tag that is required but is completely absent.
From what I have seen validation can be done againsta schema, but you must know the path to the schema in order to pass it into the setSchema() method. The problem I have is that the path to the schema is stored in the XML header and I can't knwo at run time where the schema is going to be. Which is why it's stored in the XML file:
<?xml version="1.0" encoding="utf-8"?>
<DDSSettings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="/a/big/long/path/to/a/schema/file/DDSSettings.xsd">
<Field1>1</Field1>
<Field2>-1</Field2>
...etc
Every example I see uses setValidating(true), which is now deprecated, so throws an exception.
This is the Java code I have so far, which seems to only do XML validation, not schema validation:
try
{
JAXBContext jc = new JAXBContext()
{
private final JAXBContext jaxbContext = JAXBContext.newInstance("blah");
@Override
public Unmarshaller createUnmarshaller() throws JAXBException
{
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
ValidationEventCollector vec = new ValidationEventCollector()
{
@Override
public boolean handleEvent(ValidationEvent event) throws RuntimeException
{
ValidationEventLocator vel = event.getLocator();
if (event.getSeverity() == event.ERROR || event.getSeverity() == event.FATAL_ERROR)
{
String error = "XML Validation Exception: " + event.getMessage() + " at row: " + vel.getLineNumber() + " column: " + vel.getColumnNumber();
System.out.println(error);
}
m_unmarshallingOk = false;
return false;
}
};
unmarshaller.setEventHandler(vec);
return unmarshaller;
}
@Override
public Marshaller createMarshaller() throws JAXBException
{
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
@SuppressWarnings("deprecation")
public Validator createValidator() throws JAXBException
{
throw new UnsupportedOperationException("Not supported yet.");
}
};
Unmarshaller unmarshaller = jc.createUnmarshaller();
m_ddsSettings = (com.ultra.DDSSettings)unmarshaller.unmarshal(new File(xmlfileName));
}
catch (UnmarshalException ex)
{
Logger.getLogger(UniversalDomainParticipant.class.getName()).log(
Level.SEVERE,
null, ex);
}
catch (JAXBException ex)
{
Logger.getLogger(UniversalDomainParticipant.class.getName()).log(
Level.SEVERE,
null, ex);
}
So what is the proper way to do this validation? I was expecting there to be a validate() method on the JAXB generated classes, but I guess that would be too simple for Java.
