DTD Info and Related Errors when Validating (XSD Schema) -- Can They Be Ignored?

Question

So I've got a large amount of XML files. For years they've caused trouble because the people that write them do them by hand, so errors naturally occurred. It's high time we get around to validating them and providing feedback on what's wrong when trying to use these XML files.

I'm using the SAX parser and getting a list of errors.

Below is my code

  BookValidationErrorHandler errorHandler = new BookValidationErrorHandler();

        SAXParserFactory factory = SAXParserFactory.newInstance();
        factory.setValidating(true);
        factory.setNamespaceAware(true);

        SchemaFactory schemaFactory = 
            SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");

        factory.setSchema(schemaFactory.newSchema(
            new Source[] {new StreamSource("test.xsd")}));


        javax.xml.parsers.SAXParser parser = factory.newSAXParser();
        org.xml.sax.XMLReader reader = parser.getXMLReader();

        reader.setErrorHandler(errorHandler);
        reader.parse(new InputSource("bad.xml"));

The first couple errors are always:

Line Number: 2: Document is invalid: no grammar found. Line Number: 2: Document root element "credits", must match DOCTYPE root "null".

We can't possibly go and edit these thousands of XML files that needed to be checked.

Is there anything I can easily add to the front of the source to prevent this? Is there a way to tell the parser to ignore these DTD related errors? Not even sure what the grammar one means. I sort of understand what the second one means.

score 8 · Accepted Answer · edited Jan 25 '17 at 17:21

8

Setting setValidating(true) requests DTD validation and causes a failure if no DTD exists. If you only want schema validation and not DTD validation then use setValidating(false). From the Javadoc for setValidating():

To use modern schema languages such as W3C XML Schema or RELAX NG instead of DTD, you can configure your parser to be a non-validating parser by leaving the setValidating(boolean) method false, then use the setSchema(Schema) method to associate a schema to a parser.

edited Jan 25 '17 at 17:21

user812786

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answered Mar 04 '11 at 08:59

Michael Kay

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I've changed the validation to false and I'm getting Line Number: 3: cvc-elt.1: Cannot find the declaration of element 'credits'. This *clearly* as day exists in my XML file. Very frustrating. – bobber205 Mar 04 '11 at 19:28
1

@bobber does it exist in the XSD file? That's where the validator is looking for the declaration. – xan Mar 10 '11 at 01:34
What if I don't know what the schema is before hand? For example, I may want to accept documents which conform to both `my-schema-v1.xsd` and `my-schema-v2.xsd` and select the appropriate schema for validation at run time based on the schema specified in the root element's attributes. – daiscog Jan 21 '15 at 16:37
Ah, I've found the [answer](http://stackoverflow.com/a/28073224/889583) in the [oracle docs](http://docs.oracle.com/javase/tutorial/jaxp/sax/validation.html) myself, and there's no need to use `setValidating(false)`. – daiscog Jan 21 '15 at 17:25

score 0 · Answer 2 · answered Jan 21 '15 at 17:24

You can still use a validating parser and you don't need to preset the schema in the parser, if you are using a JAXP-compliant parser and you configure it correctly as per the Oracle documentation:

SAXParserFactory spf = SAXParserFactory.newInstance();
spf.setNamespaceAware(true);
spf.setValidating(true);
SAXParser saxParser = spf.newSAXParser();
// Important step next:  Tell the parser which XML schema-definition language to expect:
saxParser.setProperty("http://java.sun.com/xml/jaxp/properties/schemaLanguage", "http://www.w3.org/2001/XMLSchema");
// Now when we parse a file without a DTD, we no longer get an error 
// (as long as an XSD schema is defined in the file):
saxParser.parse(source, handler);

score 0 · Answer 3 · answered Apr 20 '11 at 08:22

in these dais I had the same problem; I found this thread looking for a solution. My solution was to use an EntityResolver. Seems like set the Schema is not enought... not for me at least. This is an EntityResolver example:

public class CustomResolver implements EntityResolver {
    @Override
    public InputSource resolveEntity(String publicId, String systemId) 
            throws SAXException, IOException {

        if (systemId.equals("http://namespace1.example.com/ex1")) {
            return new InputSource("xsd_for_namespace1_path"));
        } else if (systemId.equals("http://namespace2.example.com/ex2")) {
            return new InputSource("xsd_for_namespace2_path"));
        } else if (systemId.equals("http://namespace3.example.com/ex3")) {
            return new InputSource("xsd_for_namespace3_path")); 
        }

        return null;
    }
}

I disable the setValidating() property too. This is my parser configuration:

SAXParserFactory saxpf = SAXParserFactory.newInstance();
saxpf.setNamespaceAware(true);
saxpf.setSchema(getSchema());
saxpf.setValidating(false);
SAXParser saxParser = saxpf.newSAXParser();
saxParser.getParser().setEntityResolver(new XSDResolver());

The method getSchema() instantiate a Schema like you do in your code but with more sources.

I hope that it can help who found that same error.

I forgot one thing! If the xml have the schemaLocaltion="Namespace path" EntityResolver wasn't necessary in validation process; the same code without the resolver setting works for me. I've the feeling that setSchema is useless but i refuse to accept it. — Leo, Apr 20 '11 at 08:35

DTD Info and Related Errors when Validating (XSD Schema) -- Can They Be Ignored?

3 Answers3