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. It always returns -1.

Is there a easy way to get the line number?

import java.io.File;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;

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

    public class XMLValidation {

        public static void main(String[] args) {

            try {
                DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
                Document document = parser.parse(new File("myxml.xml"));

                SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
                Source schemaFile = new StreamSource(new File("myschema.xsd"));

                Schema schema = factory.newSchema(schemaFile);

                Validator validator = schema.newValidator();

                validator.validate(new DOMSource(document));

            } catch (SAXParseException e) {
                System.out.println(e.getLineNumber());
                e.printStackTrace();

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

Sivas

Mads, that other post relates to C#, not java. – Sivas

Answer 1

I found this

http://www.herongyang.com/XML-Schema/Xerces2-XSD-Validation-with-XMLReader.html

that appears to provide the following details(to include line numbers)

Error:
   Public ID: null
   System ID: file:///D:/herong/dictionary_invalid_xsd.xml
   Line number: 7
   Column number: 22
   Message: cvc-datatype-valid.1.2.1: 'yes' is not a valid 'boolean' 
   value.

using this code:

/**
 * XMLReaderValidator.java
 * Copyright (c) 2002 by Dr. Herong Yang. All rights reserved.
 */
import java.io.IOException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
class XMLReaderValidator {
   public static void main(String[] args) {
      String parserClass = "org.apache.xerces.parsers.SAXParser";
      String validationFeature 
         = "http://xml.org/sax/features/validation";
      String schemaFeature 
         = "http://apache.org/xml/features/validation/schema";
      try {
         String x = args[0];
         XMLReader r = XMLReaderFactory.createXMLReader(parserClass);
         r.setFeature(validationFeature,true);
         r.setFeature(schemaFeature,true);
         r.setErrorHandler(new MyErrorHandler());
         r.parse(x);
      } catch (SAXException e) {
         System.out.println(e.toString()); 
      } catch (IOException e) {
         System.out.println(e.toString()); 
      }
   }
   private static class MyErrorHandler extends DefaultHandler {
      public void warning(SAXParseException e) throws SAXException {
         System.out.println("Warning: "); 
         printInfo(e);
      }
      public void error(SAXParseException e) throws SAXException {
         System.out.println("Error: "); 
         printInfo(e);
      }
      public void fatalError(SAXParseException e) throws SAXException {
         System.out.println("Fattal error: "); 
         printInfo(e);
      }
      private void printInfo(SAXParseException e) {
         System.out.println("   Public ID: "+e.getPublicId());
         System.out.println("   System ID: "+e.getSystemId());
         System.out.println("   Line number: "+e.getLineNumber());
         System.out.println("   Column number: "+e.getColumnNumber());
         System.out.println("   Message: "+e.getMessage());
      }
   }
}

Reincarnate

thanks for your answer, but where should I put the XSD file? – Mazurka

Answer 2

Replace this line:

validator.validate(new DOMSource(document));

by

validator.validate(new StreamSource(new File("myxml.xml")));

will let the SAXParseException contain line number & column number

Reflate

Answer 3

Try using a SAXLocator http://download.oracle.com/javase/1.5.0/docs/api/org/xml/sax/Locator.html Parsers are not required to supply one, but if they do it should report line numbers

I think your code should include:

 // this will be called when XML-parser starts reading
    // XML-data; here we save reference to current position in XML:
    public void setDocumentLocator(Locator locator) {
        this.locator = locator;
    }

(see http://www.java-tips.org/java-se-tips/org.xml.sax/using-xml-locator-to-indicate-current-parser-pos.html)

The parser will give you a locator which you can then use to get the line number. It's probably worth printing/debugging when this happens to see if you have a valid locator

Mesocratic

I saw that Locator interface, but I was unable to relate the Locator and the Validator. The problem remains unsolved here. – Sivas

You will probbaly have to set the Locator. Here is an example. exampledepot.com/egs/org.xml.sax/SetLocator.html I can't guarantee it will work. If the locator does work you could set it on every sax event and read the latest successful event – Mesocratic

Cache: web.archive.org/web/20120919100052/http://www.exampledepot.com/… – Daniels

Answer 4

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 + '"');
    }
}

Rossiter