Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that stores xml schema information 

 *  Copyright: 2008 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Jing Tao

 * 

 *   '$Author: leinfelder $'

 *     '$Date: 2008-09-26 15:43:57 -0700 (Fri, 26 Sep 2008) $'

 * '$Revision: 4399 $'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.service;

import java.io.IOException;

import java.io.InputStream;

import java.util.Vector;

import org.xml.sax.Attributes;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.DefaultHandler;

import org.xml.sax.helpers.XMLReaderFactory;

import edu.ucsb.nceas.metacat.properties.PropertyService;

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

/**

 * A class will parse an schema file to get information - such as included 

 * xsd files in this schema

 * @author tao

 *

 */

public class XMLSchemaParser extends DefaultHandler

{

  private static String INCLUDE = "include";

  private static String SCHEMALOCATION = "schemaLocation";

  private Vector<String> includedSchemaFilePaths = new Vector<String>();

  private InputStream schemaIn = null;

  private XMLReader parser = null;

  /**

   * Constructor

   * @param schemaIn the schema content as an InputStream object

   */

  public XMLSchemaParser(InputStream schemaIn) throws SAXException, PropertyNotFoundException

  {

    this.schemaIn =schemaIn;

    initParser();

  }

  /*

   * Initialize sax parser

   */

  private void initParser() throws SAXException, PropertyNotFoundException

  {   

    // Get an instance of the parser

     String parserName = PropertyService.getProperty("xml.saxparser");

     parser = XMLReaderFactory.createXMLReader(parserName);

     parser.setContentHandler(this);

  }

  /**

   * Parse the schema file

   * @throws SAXException if some sax related exception happens

   * @throws IOException if the schema content couldn't be found

   */

  public void parse() throws SAXException, IOException

  {

    parser.parse(new InputSource(schemaIn));

  }

  /**

   * Get the included schema file paths in this schema

   * @return the included schema file paths

   */

  public Vector<String> getIncludedSchemaFilePathes()

  {

    return includedSchemaFilePaths;

  }

  /** SAX Handler that is called at the start of each XML element */

  public void startElement(String uri, String localName, String qName,

          Attributes atts) throws SAXException

  {

    if(localName != null && localName.equals(INCLUDE) && atts != null)

    {

      for (int i = 0; i < atts.getLength(); i++) 

      {

        String attributeName = atts.getQName(i);

        if(attributeName != null && attributeName.equals(SCHEMALOCATION))

        {

          String attributeValue = atts.getValue(i);

          if(attributeValue != null || !attributeValue.trim().equals(""))

          {

            includedSchemaFilePaths.add(attributeValue);

          }

        }

      }

    }

  }

}