Metacat

/**

 *        Name: DBSAXHandler.java

 *     Purpose: A Class that implements org.xml.sax.EntityResolver interface

 *              for resolving external entities

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

 *              National Center for Ecological Analysis and Synthesis

 *     Authors: Jivka Bojilova

 *

 *     Version: '$Id: DBEntityResolver.java 74 2000-05-05 00:37:58Z jones $'

 */

package edu.ucsb.nceas.metacat;

import org.xml.sax.*;

import java.sql.*;

import java.net.URL;

import java.net.MalformedURLException;

import java.util.Stack;

import java.util.EmptyStackException;

/** 

 * A database aware Class implementing EntityResolver interface for the SAX parser to

 * call when processing the XML stream and intercepting any external entities

 * (including the external DTD subset and external parameter entities, if any) before including them.

 */

public class DBEntityResolver implements EntityResolver

{

   static String doctype = null;

   static Connection conn = null;

   private int pIdCounter = 0;

   private long currentElementNo;

   /** Construct an instance of the DBEntityResolver clas

    *

    * @param conn the JDBC connection to which information is written

    */

   public DBEntityResolver(Connection conn)

   {

      this.conn = conn;

   }

   /** The Parser call this method before opening any external entity 

     * except the top-level document entity (including the external DTD subset,

     * external entities referenced within the DTD, and external entities referenced 

     * within the document element)*/

   public InputSource resolveEntity (String publicId, String systemId)

            throws MalformedURLException

   {

     String dbSystemId;

     if (publicId != null) {

        pIdCounter += 1;

        currentElementNo = DBSAXHandler.elementNo;

        System.out.println("from DBEntityResolver: current element is " + DBSAXHandler.elementNo);

        System.out.println("from DBEntityResolver: " + pIdCounter + " " + publicId);

        // look at the db XML Catalog and get dbSystemId by this publicId

        if (currentElementNo == 0) {

            doctype = publicId;

            dbSystemId = getDTDSystemID (conn, publicId);

            if (dbSystemId == "")

                // register publicId in db and use the provided systemId

                if (systemId != "") {

                    System.out.println("from DBEntityResolver: " + systemId);

                    new URL(systemId);

                    registerDTDPublicID (conn, publicId, systemId);

                    return null;

                }

            new URL(dbSystemId);

            System.out.println("from DBEntityResolver: db System ID: " + dbSystemId);

            return new InputSource(dbSystemId);

        } 

        else {

            // look at the db XML Catalog and get dbSystemId by this publicId for a given doctype

            dbSystemId = getEntitySystemID (conn, doctype, publicId);

            if (dbSystemId == "")

                // register publicId in db for a given doctype and use the provided systemId

                if (systemId != "") {

                    System.out.println("from DBEntityResolver: " + systemId);

                    new URL(systemId);

                    registerEntityPublicID (conn, doctype, publicId, systemId);

                    return null;

                }

            new URL(dbSystemId);

            System.out.println("from DBEntityResolver: db System ID: " + dbSystemId);

            return new InputSource(dbSystemId);

        }  

     }

     if ( systemId != null) {

        System.out.println("from DBEntityResolver: " + systemId);

        new URL(systemId);

     }

     // use the default behaviour

     return null;

   }

   /** Look at db XML Catalog to get System ID (if any) for that Public ID.

     * Return empty string if there are not */

   private String getDTDSystemID (Connection conn, String publicId)

   {

        String system_id = "";

        Statement stmt;

        try {

          stmt = conn.createStatement();

          stmt.execute("SELECT system_id FROM xml_catalog_entities a, xml_catalog b " + 

                       "WHERE a.entity_type = 'DTD' AND a.source_doctype = b.doctype AND b.doctype = '" + publicId + "'");

          try {

            ResultSet rs = stmt.getResultSet();

            try {

              boolean tableHasRows = rs.next();

              if (tableHasRows) {

                try {

                  system_id = rs.getString(1);

                } catch (SQLException e) {

                  System.out.println("DBEntityResolver.getDTDSystemID() - Error with getString: " + e.getMessage());

                }

              }

            } catch (SQLException e) {

              System.out.println("DBEntityResolver.getDTDSystemID() - Error with next: " + e.getMessage());

            }

          } catch (SQLException e) {

            System.out.println("DBEntityResolver.getDTDSystemID() - Error with getrset: " + e.getMessage());

          }

          stmt.close();

        } catch (SQLException e) {

          System.out.println("DBEntityResolver.getDTDSystemID() - Error getting id: " + e.getMessage());

        }

        // return the selected System ID

        return system_id;

   }

   /** Register Public ID in db XML Catalog */

   private void registerDTDPublicID (Connection conn, String publicId, String systemId)

   {

        try {

          conn.setAutoCommit(false);

          PreparedStatement pstmt;

          pstmt = conn.prepareStatement(

                "INSERT INTO xml_catalog (doctype) VALUES (?)");

          // Bind the values to the query

          pstmt.setString(1, publicId);

          // Do the insertion

          pstmt.execute();

          pstmt.close();

          pstmt = conn.prepareStatement(

                "INSERT INTO xml_catalog_entities (entity_id, entity_type, source_doctype, system_id) " +

                "VALUES (null, 'DTD', ?, ?)");

          // Bind the values to the query

          pstmt.setString(1, publicId);

          pstmt.setString(2, systemId);

          // Do the insertion

          pstmt.execute();

          pstmt.close();

          conn.commit();

          conn.setAutoCommit(true);

        } catch (SQLException e) {

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

        }

   }

   /** Look at db XML Catalog to get System ID (if any) for that Public ID and doctype.

     * Return empty string if there are not */

   private String getEntitySystemID (Connection conn, String doctype, String publicId)

   {

        String system_id = "";

        Statement stmt;

        try {

          stmt = conn.createStatement();

          stmt.execute("SELECT system_id FROM xml_catalog_entities " + 

                       "WHERE entity_type = 'ENTITY' AND source_doctype = '" + doctype + "' AND public_id = '" + publicId + "'");

          try {

            ResultSet rs = stmt.getResultSet();

            try {

              boolean tableHasRows = rs.next();

              if (tableHasRows) {

                try {

                  system_id = rs.getString(1);

                } catch (SQLException e) {

                  System.out.println("DBEntityResolver.getEntitySystemID() - Error with getString: " + e.getMessage());

                }

              }

            } catch (SQLException e) {

              System.out.println("DBEntityResolver.getEntitySystemID() - Error with next: " + e.getMessage());

            }

          } catch (SQLException e) {

            System.out.println("DBEntityResolver.getEntitySystemID() - Error with getrset: " + e.getMessage());

          }

          stmt.close();

        } catch (SQLException e) {

          System.out.println("DBEntityResolver.getEntitySystemID() - Error getting id: " + e.getMessage());

        }

        // return the selected System ID number

        return system_id;

   }

   /** Register Public ID in db XML Catalog */

   private void registerEntityPublicID (Connection conn, String doctype, String publicId, String systemId)

   {

        try {

          conn.setAutoCommit(false);

          PreparedStatement pstmt;

          pstmt = conn.prepareStatement(

                "INSERT INTO xml_catalog_entities (entity_id, entity_name, entity_type, source_doctype, public_id, system_id) " +

                "VALUES (null, null, 'ENTITY', ?, ?, ?)");

          // Bind the values to the query

          pstmt.setString(1, doctype);

          pstmt.setString(2, publicId);

          pstmt.setString(3, systemId);

          // Do the insertion

          pstmt.execute();

          pstmt.close();

          conn.commit();

          conn.setAutoCommit(true);

        } catch (SQLException e) {

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

        }

   }

}