package demo;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import java.io.IOException;
import java.io.InputStream;

import org.jdom.Document;
import org.jdom.JDOMException;

import org.jdom.input.SAXBuilder;

import org.jdom.output.XMLOutputter;

/**
 * Class ValidDocument provides an XML document validated a schema.
 * @author David Morris
 */
public class ValidDocument {
    public Document build(InputStream xmlFile, String xmlSchema)
        throws JDOMException, IOException {
        // Create new SAXBuilder, using default parser
        SAXBuilder builder =
            new SAXBuilder("org.apache.xerces.parsers.SAXParser", true);
      builder.setEntityResolver(new SchemaLoader());

        // Uncommenting the following line ensures that the document received stands alone
        // builder.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
        builder.setFeature(
            "http://apache.org/xml/features/validation/schema",
            true);
        builder.setProperty(
            "http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation",
            "file:///" + xmlSchema);

        Document doc = builder.build(xmlFile);

        return doc;
    }

    public static void main(String[] args) {
        if (args.length < 2) {
            System.err.println(
                "Usage: java demo.ValidDocument <fileLocation> <xmlSchemaLocation>");
        }

        try {
            InputStream xmlFile =
                Thread
                    .currentThread()
                    .getContextClassLoader()
                    .getResourceAsStream(
                    args[0]);
                    ValidDocument vd = new ValidDocument();
            Document doc = vd.build(xmlFile, args[1]);

            // Output the document to System.out
            XMLOutputter outputter = new XMLOutputter();
            outputter.output(doc, System.out);
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }

        System.exit(0);
    }
    public class SchemaLoader implements EntityResolver {
        public InputSource resolveEntity(String publicId, String systemId)
            throws IOException, SAXException {
            if (systemId.toLowerCase().endsWith(".xsd")) {
                InputStream is = 
                Thread
                    .currentThread()
                    .getContextClassLoader()
                    .getResourceAsStream(systemId.substring(8)); // Drop file:///
                return new InputSource(is);
            } else {
                return null;
            }
        }
    }
}