How to get error's line number while validating a XML file against a XML schema

Question

I\'m trying to validade a XML against a W3C XML Schema.

The following code does the job and reports when error occurs. But I\'m unable to get line number of the error. I

Answer 1

Assuming the final objective is to have a validated DOM instance, the previous answers would require XML documents to be read twice — first for validation, and then again to build the object tree. That's fine if the document is given as a file path, but it would require some sort of workaround if it were provided as an input stream, which in principle can only be read once.

A more efficient alternative is to use a validating parser to check the XML document against the schema as the object tree is built. See the code below for how to setup a schema-validating DOM parser:

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.w3c.dom.Document;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

public class XML {
    public static Document load(String xml, String xsd) {
        // The default error handler just prints errors to the standard error output. In
        // order to make the parser interrupt its work once a validation error is found,
        // we need to use a custom handler that throws an exception in response to any
        // reported issues.
        ErrorHandler errorHandler = new ErrorHandler() {
            @Override
            public void error(SAXParseException exception) throws SAXException {
                throw exception;
            }

            @Override
            public void fatalError(SAXParseException exception) throws SAXException {
                throw exception;
            }

            @Override
            public void warning(SAXParseException exception) throws SAXException {
                throw exception;
            }
        };

        try {
            SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
            Schema schema = factory.newSchema(new File(xsd));

            DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
            builderFactory.setNamespaceAware(true);
            builderFactory.setSchema(schema);

            DocumentBuilder builder = builderFactory.newDocumentBuilder();
            builder.setErrorHandler(errorHandler);

            InputStream input = new FileInputStream(xml);
            Document document = builder.parse(input);

            return document;
        }
        catch (SAXParseException e) {
          int row = e.getLineNumber();
          int col = e.getColumnNumber();
          String message = e.getMessage();
          System.out.println("Validation error at line " + row + ", column " + col + ": \"" + message + '"');
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    public static void main(String[] args) {
        String xml = args[0];
        String xsd = args[1];

        Document document = load(xml, xsd);
        boolean valid = (document != null);

        System.out.println("Document \"" + xml + "\" is " + (valid ? "" : "not ") + "valid against schema \"" + xsd + '"');
    }
}