import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;

// A Simple SAX Application using JAXP with Namespace support
public class SimpleSchema{
	private SAXParserFactory factory; // Creates parser object
	private SAXParser parser; // Holds a parser object
	private XMLReader xmlReader; // Object that parses the file
	private DefaultHandler handler; // Defines the handler for this parser
	private boolean valid = true;
	
	// Set schema constants
    static final String JAXP_SCHEMA_LANGUAGE =
        "http://java.sun.com/xml/jaxp/properties/schemaLanguage";
    static final String W3C_XML_SCHEMA =         "http://www.w3.org/2001/XMLSchema";
    static final String JAXP_SCHEMA_SOURCE =         "http://java.sun.com/xml/jaxp/properties/schemaSource";

	
	public SimpleSchema() throws SAXException{
		try{
			factory = SAXParserFactory.newInstance();
			factory.setValidating(true);
		    factory.setNamespaceAware(true);
			
			if (factory.isValidating()){
				System.out.println("The parser is validating");
			}
			
			//Create Parser
			parser = factory.newSAXParser();
			
			// Enable Schemas
			parser.setProperty(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
			
			//Create XMLReader
			xmlReader = parser.getXMLReader();
						
			ContentHandler cHandler = new MyDefaultHandler();
			ErrorHandler eHandler = new MyDefaultHandler();
			
			xmlReader.setContentHandler(cHandler);
			xmlReader.setErrorHandler(eHandler);
			
		}  catch (ParserConfigurationException e){
			e.printStackTrace();
		} catch (SAXException e){
			e.printStackTrace();
		}
	}
	
	public void parseDocument(String xmlFile){
		try{
			xmlReader.parse(xmlFile);
			if (valid) {
				System.out.println("Document is valid!");
			}
		} catch (SAXException e){
			e.printStackTrace();
		} catch (IOException e){
			e.printStackTrace();
		} catch (Exception e){
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args){
        try {
            if (args.length != 1) {
                System.out.println(
                    "Usage: java SimpleSchema " +
                    "[XML Document Filename]");
                System.exit(0);
            }
			SimpleSchema xmlApp = new SimpleSchema();
			xmlApp.parseDocument(args[0]);
        } catch (SAXException e){
			e.printStackTrace();
		} catch (Exception e) {
            e.printStackTrace();
        }
	}
	
	class MyDefaultHandler extends DefaultHandler{
		private CharArrayWriter buff = new CharArrayWriter();
		private String errMessage = "";
		/* With a handler class, just override the methods you need to use
		*/

		// Start Error Handler code here
		public void warning(SAXParseException e) {
			System.out.println("Warning Line " + e.getLineNumber() + ": " + e.getMessage() + "\n");
		}
		
		public void error(SAXParseException e) {
			errMessage = new String("Error Line " + e.getLineNumber() + ": " + e.getMessage() + "\n");
			System.out.println(errMessage);
			valid = false;
		}

		public void fatalError(SAXParseException e) {
			errMessage = new String("Error Line " + e.getLineNumber() + ": " + e.getMessage() + "\n");
			System.out.println(errMessage);
			valid = false;
		}
	}
}