XML validation against DTD

Question

Hi,
I have an application that receives XML from an external source. The XML received does not have the XML version and the doc type declaration lines. I want to validate the XML against a DTD.
One dirty way of doing this is to open the XML received and prepend the XML versions and doctype lines to it. And then parse the XML. But is it the right way to do it?
What I would like to know is that does the XML parser provide any API which can tell it to validate an XML document against a certain DTD.

Answer 1

Yes, there is an API to do this. You have to do something like this:
DocumentBuilderFactory dbf          =DocumentBuilderFactory.newInstance();
dbf.setValidating(true);
DocumentBuilder db = dbf.newDocumentBuilder();
XMLErrors eh = new XMLErrors(frame);
db.setErrorHandler(eh);
Document doc = db.parse(f);
(where f is the XML file)
In this example, the class XMLErrors is used as the ErrorHandler. XMLErrors extends the DefaultHandler class and provides the user with information about the various error levels. A call to the over-ridden "error" method notifies the user (using a Dialog box) that the document doesn't meet the DTD.
Hope this helps.