In my XML file I have some entities such as ’
So I have created a DTD tag for my XML document to define these entities. Below is the Java code used to read the XML file.
SAXBuilder builder = new SAXBuilder();
URL url = new URL("http://127.0.0.1:8080/sample/subject.xml");
InputStream stream = url.openStream();
org.jdom.Document document = builder.build(stream);
Element root = document.getRootElement();
Element name = root.getChild("name");
result = name.getText();
System.err.println(result);
How can I change the Java code to retrieve a DTD over HTTP to allow the parsing of my XML document to be error free?
Simplified example of the xml document.
<main>
<name>hello ‘ world ’ foo & bar </name>
</main>
One way to do this would be to read the document and then validate it with the transformer:
import java.net.URL;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
public class ValidateWithExternalDTD {
private static final String URL = "http://127.0.0.1:8080/sample/subject.xml";
private static final String DTD = "http://127.0.0.1/YourDTD.dtd";
public static void main(String args[]) {
try {
DocumentBuilderFactory factory= DocumentBuilderFactory.newInstance();
factory.setValidating(true);
DocumentBuilder builder = factory.newDocumentBuilder();
// Set the error handler
builder.setErrorHandler(new org.xml.sax.ErrorHandler() {
public void fatalError(SAXParseException spex)
throws SAXException {
// output error and exit
spex.printStackTrace();
System.exit(0);
}
public void error(SAXParseException spex)
throws SAXParseException {
// output error and continue
spex.printStackTrace();
}
public void warning(SAXParseException spex)
throws SAXParseException {
// output warning and continue
spex.printStackTrace();
}
});
// Read the document
URL url = new URL(ValidateWithExternalDTD.URL);
Document xmlDocument = builder.parse(url.openStream());
DOMSource source = new DOMSource(xmlDocument);
// Use the tranformer to validate the document
StreamResult result = new StreamResult(System.out);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, ValidateWithExternalDTD.DTD);
transformer.transform(source, result);
// Process your document if everything is OK
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
Another way would be to replace the XML title with the XML title plus the DTD reference
Replace this:
<?xml version = "1.0"?>
with this:
<?xml version = "1.0"?><!DOCTYPE ...>
Of course you would replace the first occurance only and not try to go through the whole xml document
You have to instantiate the SAXBuilder by passing true(validate) to its constructor:
SAXBuilder builder = new SAXBuilder(true);
or call:
builder.setValidation(true)