Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that transforms an XML text document

 *             into a another type using XSL

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones

 *

 *   '$Author: jones $'

 *     '$Date: 2000-06-26 03:35:05 -0700 (Mon, 26 Jun 2000) $'

 * '$Revision: 203 $'

 */

package edu.ucsb.nceas.metacat;

import java.io.*;

import java.net.URL;

import java.net.MalformedURLException;

import java.sql.*;

import java.util.Stack;

import oracle.xml.parser.v2.XSLStylesheet;

import oracle.xml.parser.v2.XSLException;

import oracle.xml.parser.v2.XSLProcessor;

import oracle.xml.parser.v2.XMLDocument;

import oracle.xml.parser.v2.DOMParser;

/** 

 * A Class that transforms XML documents utitlizing XSL style sheets

 */

public class DBTransform {

  private Connection	conn = null;

  /**

   * construct a DBTransform instance.

   *

   * Generally, one calls transformXMLDocument() after constructing the instance

   *

   * @param conn the database connection from which to lookup the public ids

   */

  public DBTransform( Connection conn ) 

                  throws IOException, 

                         SQLException, 

                         ClassNotFoundException

  {

    this.conn = conn;

  }

  /**

   * Transform an XML document using the stylesheet reference from the db

   *

   * @param doc the document to be transformed

   * @param sourcetype the document type of the source

   * @param targettype the target document type

   */

  public void transformXMLDocument(String doc, String sourcetype, 

                String targettype, PrintWriter pw) {

    // Look up the stylesheet for this type combination

    String xsl_system_id = getSystemId("XSL", sourcetype, targettype);

    if (xsl_system_id != null) {

      // Create a stylesheet from the system id that was found

      try {

        XSLStylesheet style = new XSLStylesheet(new URL(xsl_system_id), null);

        DOMParser dp = new DOMParser();

        dp.setValidationMode(false);

        dp.parse((Reader)(new StringReader(doc)));

        new XSLProcessor().processXSL(style, dp.getDocument(), pw);

      } catch (Exception e) {

        pw.println(xsl_system_id + "Error transforming document:\n" + 

                   e.getMessage());

      }

    } else {

      // No stylesheet registered form this document type, so just return the 

      // XML stream we were passed

      pw.print(doc);

    }

  }

  /**

   * Lookup a stylesheet reference from the db catalog

   *

   * @param objecttype the type of the object we want to retrieve

   * @param sourcetype the document type of the source

   * @param targettype the document type of the target

   */

  public String getSystemId(String objecttype, String sourcetype, 

                String targettype) {

    // Look up the System ID of a particular object

    PreparedStatement pstmt;

    String the_system_id = null;

    try {

      pstmt =

        conn.prepareStatement("SELECT system_id " +

                "FROM xml_catalog " +

                "WHERE entry_type LIKE ? " +

                "AND source_doctype LIKE ? " +

                "AND target_doctype LIKE ? ");

      // Bind the values to the query

      pstmt.setString(1, objecttype);

      pstmt.setString(2, sourcetype);

      pstmt.setString(3, targettype);

      pstmt.execute();

      try {

        ResultSet rs = pstmt.getResultSet();

        try {

          boolean tableHasRows = rs.next();

          if (tableHasRows) {

            try {

              the_system_id = rs.getString(1);

            } catch (SQLException e) {

              System.out.println("Error with getString: " + e.getMessage());                }

          } else {

            the_system_id = null; 

          }

        } catch (SQLException e) {

          System.err.println("Error with next: " + e.getMessage());

          return ("Error with next: " + e.getMessage());

        }

      } catch (SQLException e) {

        System.err.println("Error with getrset: " + e.getMessage());

        return ("Error with getrset: " + e.getMessage());

      }

      pstmt.close();

    } catch (SQLException e) {

      System.err.println("Error getting id: " + e.getMessage());

      return ("Error getting id: " + e.getMessage());

    }

    return the_system_id;

  }

  /**

   * the main routine used to test the transform utility.

   *

   * Usage: java DBTransform

   */

  static public void main(String[] args) {

     if (args.length > 0)

     {

        System.err.println("Wrong number of arguments!!!");

        System.err.println("USAGE: java DBTransform");

        return;

     } else {

        try {

          // Open a connection to the database

          MetaCatUtil   util = new MetaCatUtil();

          Connection dbconn = util.openDBConnection();

          // Create a test document

          StringBuffer testdoc = new StringBuffer();

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

          testdoc.append("<eml-dataset><metafile_id>NCEAS-0001</metafile_id>");

          testdoc.append("<dataset_id>DS001</dataset_id>");

          testdoc.append("<title>My test doc</title></eml-dataset>");

          // Transform the document to the new doctype

          DBTransform dbt = new DBTransform(dbconn);

          dbt.transformXMLDocument(testdoc.toString(), 

                                   "-//NCEAS//eml-dataset//EN", 

                                   "-//W3C//HTML//EN", 

                                   new PrintWriter(System.out));

        } catch (Exception e) {

          System.err.println("EXCEPTION HANDLING REQUIRED");

          System.err.println(e.getMessage());

          e.printStackTrace(System.err);

        }

     }

  }

  private void dbg(int position) {

    System.err.println("Debug flag: " + position);

  }

}

/**

 * '$Log$

 * 'Revision 1.7.2.2  2000/06/25 23:38:16  jones

 * 'Added RCSfile keyword

 * '

 * 'Revision 1.7.2.1  2000/06/25 23:34:18  jones

 * 'Changed documentation formatting, added log entries at bottom of source files

 * ''

 */