Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that validates XML documents

 *             This class is designed to be 'parser independent

 *             i.e. it uses only org.xml.sax classes

 *             It is tied to SAX 2.0 methods

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Dan Higgins, Matt Jones

 *    Release: @release@

 * 

 *   '$Author: jones $'

 *     '$Date: 2001-01-18 11:52:00 -0800 (Thu, 18 Jan 2001) $'

 * '$Revision: 669 $'

 *

 * 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;

import java.net.URL;

import java.net.MalformedURLException;

import java.util.*;

import java.io.*;

import java.lang.reflect.*;

import java.sql.*;

import org.w3c.dom.*;

import org.xml.sax.*;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.XMLReaderFactory;

import com.arbortext.catalog.*;

/**

 * Name: DBValidate.java

 *       Purpose: A Class that validates XML documents

 * 			   This class is designed to be parser independent

 *    			   i.e. it uses only org.xml.sax classes

 * 			   It is tied to SAX 2.0 methods

 *     Copyright: 2000 Regents of the University of California and the

 *                National Center for Ecological Analysis and Synthesis

 *                April 28, 2000

 *    Authors: Dan Higgins, Matt Jones

 */

public class DBValidate {

  static int WARNING = 0;

  static int ERROR=1;

  static int FATAL_ERROR=2;

  XMLReader parser;

  ErrorStorer ef;

  String xml_doc; // document to be parsed

  /** Construct a new validation object */

  public DBValidate(String parserName) {

    try {

      // Get an instance of the parser

      parser = XMLReaderFactory.createXMLReader(parserName);

      parser.setFeature("http://xml.org/sax/features/validation",true);

      //parser.setValidationMode(true);     // Oracle

    } catch (Exception e) {

      System.err.println("Could not create parser!!!");

    }

  }

  /** Construct a new validation object using an OASIS catalog file */

  public DBValidate(String parserName, String xmlcatalogfile)  {

    this(parserName);

    CatalogEntityResolver cer = new CatalogEntityResolver();

    try {

      Catalog myCatalog = new Catalog();

      myCatalog.loadSystemCatalogs();

      myCatalog.parseCatalog(xmlcatalogfile);

      cer.setCatalog(myCatalog);

    } catch (Exception e) {System.out.println("Problem creating Catalog!");}

    parser.setEntityResolver(cer);

  }

  /** Construct a new validation object using a database entity resolver */

  public DBValidate(String parserName, Connection conn) {

    this(parserName);

    DBEntityResolver dbresolver = new DBEntityResolver(conn);

    parser.setEntityResolver(dbresolver);

  }

  /** 

   * validate an xml document against its DTD

   *

   * @param doc the filename of the document to validate

   */

  public boolean validate(String doc) {

    xml_doc = doc;    

    ef = new ErrorStorer();

    ef.resetErrors();

    parser.setErrorHandler(ef);

    try {

      parser.parse((createURL(xml_doc)).toString());

    } catch (IOException e) {

      System.out.println("IOException:Could not parse :"+xml_doc);

      ParseError eip = null;

      eip = new ParseError("",0,0,

                "IOException:Could not parse :"+xml_doc);

      if (ef.errorNodes == null)  ef.errorNodes = new Vector();

      ef.errorNodes.addElement(eip);

    } catch (Exception e) {} 

      // {System.out.println("Exception parsing:Could not parse :"+xml_doc);} 

    if (ef != null && ef.getErrorNodes()!=null && 

      ef.getErrorNodes().size() > 0 ) {

      return false; 

    } else {

      return true;

    }

  }

  /** 

   * validate an xml document against its DTD

   *

   * @param xmldoc the String containing the xml document to validate

   */

  public boolean validateString(String xmldoc) {

    // string is actual XML here, NOT URL or file name    

    ef = new ErrorStorer();

    ef.resetErrors();

    parser.setErrorHandler(ef);

    InputSource is = new InputSource(new StringReader(xmldoc));

    try {

      parser.parse(is);

    }

    catch (Exception e) {System.out.println("Error in parsing!");}

    if (ef != null && ef.getErrorNodes()!=null && 

      ef.getErrorNodes().size() > 0 ) {

      return false; 

    } else {

      return true;

    }

  }

  /** provide a list of errors from the validation process */

  public String returnErrors() {

    StringBuffer errorstring = new StringBuffer();

    errorstring.append("<?xml version=\"1.0\" ?>\n");

    if (ef != null && ef.getErrorNodes()!=null && 

        ef.getErrorNodes().size() > 0 ) {

      Vector errors = ef.getErrorNodes();

      errorstring.append("<validationerrors>\n");

      for (Enumeration e = errors.elements() ; e.hasMoreElements() ;) {

        errorstring.append(

                      ((ParseError)(e.nextElement())).toXML());

      }

      errorstring.append("</validationerrors>\n");

    } else {

      errorstring.append("<valid />\n");

    }

    return errorstring.toString();

  }

  /** Create a URL object from either a URL string or a plain file name. */

  private URL createURL(String name) throws Exception {

    try {

      URL u = new URL(name);

      return u;

    } catch (MalformedURLException ex) {

    }

    URL u = new URL("file:" + new File(name).getAbsolutePath());

    return u;

  }    

  /** 

   * main method for testing 

   * <p>

   * Usage: java DBValidate <xmlfile or URL>

   */

  public static void main(String[] args) {

    if (args.length != 1) {

      System.out.println("Usage: java DBValidate <xmlfile or URL>");

      System.exit(0);

    }

    String doc = args[0];

    MetaCatUtil util = new MetaCatUtil();

    try {

      Connection conn = util.openDBConnection();

      DBValidate gxv = new DBValidate(util.getOption("saxparser"), conn);

      if (gxv.validate(doc)) {

        System.out.print(gxv.returnErrors());

      } else {

        System.out.print(gxv.returnErrors());

      }

    } catch (SQLException e) {

      System.out.println("<error>Couldn't open database connection.</error>");

    } catch (ClassNotFoundException e) {

      System.out.println("<error>Couldn't open database connection.</error>");

    }

  }

  /**

   * ErrorStorer has been revised here to simply create a Vector of 

   * ParseError objects

   *

   */

  class ErrorStorer implements ErrorHandler {

    //

    // Data

    //

    Vector errorNodes = null;

    /**

     * Constructor

     */

    public ErrorStorer() {

    }

    /**

     * The client is is allowed to get a reference to the Hashtable,

     * and so could corrupt it, or add to it...

     */

    public Vector getErrorNodes() {

        return errorNodes;

    }

    /**

     * The ParseError object for the node key is returned.

     * If the node doesn't have errors, null is returned.

     */

    public Object getError() {

        if (errorNodes == null)

            return null;

        return errorNodes;

    }

    /**

     * Reset the error storage.

     */

    public void resetErrors() {

        if (errorNodes != null)

        errorNodes.removeAllElements();

    }

    /***/

    public void warning(SAXParseException ex) {

        handleError(ex, WARNING);

    }

    public void error(SAXParseException ex) {

        handleError(ex, ERROR);

    }

    public void fatalError(SAXParseException ex) throws SAXException {

        handleError(ex, FATAL_ERROR);

    }

    private void handleError(SAXParseException ex, int type) {

      // System.out.println("!!! handleError: "+ex.getMessage());

      if (errorNodes == null) {

        errorNodes = new Vector();

      }

      ParseError eip = null;

      eip = new ParseError(ex.getSystemId(), ex.getLineNumber(),

                           ex.getColumnNumber(), ex.getMessage());

      // put it in the Hashtable.

      errorNodes.addElement(eip);

    }

  }

  /**

   * The ParseError class wraps up all the error info from

   * the ErrorStorer's error method.

   *

   * @see ErrorStorer

   */

  class ParseError extends Object {

    //

    // Data

    //

    String fileName;

    int lineNo;

    int charOffset;

    String msg;

    /**

     * Constructor

     */

    public ParseError(String fileName, int lineNo, int charOffset, String msg) {

      this.fileName=fileName;

      this.lineNo=lineNo;

      this.charOffset=charOffset;

      this.msg=msg;

    }

    //

    // Getters...

    //

    public String getFileName() { return fileName; }

    public int getLineNo() { return lineNo; }

    public int getCharOffset() { return charOffset;}

    public String getMsg() { return msg; }

    public void setMsg(String s) { msg = s; }

    /** Return the error message as an xml fragment */

    public String toXML() {

      StringBuffer err = new StringBuffer();

      err.append("<error>\n");

      err.append("<filename>").append(getFileName()).append("</filename>\n");

      err.append("<line>").append(getLineNo()).append("</line>\n");

      err.append("<offset>").append(getCharOffset()).append("</offset>\n");

      err.append("<message>").append(getMsg()).append("</message>\n");

      err.append("</error>\n");

      return err.toString();

    }

  }

}