Metacat

/**

 *        Name: DBSAXElement.java

 *     Purpose: A Class that represents an XML element and its contents

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

 *              National Center for Ecological Analysis and Synthesis

 *     Authors: Matt Jones

 *

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

 */

package edu.ucsb.nceas.metacat;

import java.sql.*;

import java.io.IOException;

import java.util.Hashtable;

import java.util.Enumeration;

/** 

 * A Class that represents an XML element and its contents and

 * can write its own representation to a database connection

 */

public class DBSAXElement extends BasicElement {

    private Connection		conn;

    /** 

     * Construct a new element instance

     *

     * @param conn the JDBC Connection to which all information is written

     * @param tagname the name of the element

     * @param parent_id the parent id number for this element

     */

    public DBSAXElement (Connection conn, String tagname, 

                         long parent_id, int nodeIndex) {

      super(tagname, parent_id, nodeIndex);

      this.conn = conn;

      writeElementToDB();

    }

    /** creates SQL code and inserts new element into DB connection */

    private void writeElementToDB() {

        try {

          conn.setAutoCommit(false);

          PreparedStatement pstmt;

          if (getParentID() != 0) {

            pstmt = conn.prepareStatement(

                "INSERT INTO xml_nodes (nodeid, nodetype, " +

                "nodename, parentnodeid, nodeindex) VALUES (null, ?, ?, ?, ?)");

          } else {

            pstmt = conn.prepareStatement(

                "INSERT INTO xml_nodes (nodeid, nodetype, nodename) " +

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

          }

          // Bind the values to the query

          pstmt.setString(1, "ELEMENT");

          pstmt.setString(2, getTagName());

          //pstmt.setInt(4, null);

          if (getParentID() != 0) {

            pstmt.setLong(3, getParentID());

            pstmt.setInt(4, getNodeIndex());

          }

          // Do the insertion

          pstmt.execute();

          pstmt.close();

          setElementID(getAssignedElementID());

          conn.commit();

          conn.setAutoCommit(true);

        } catch (SQLException e) {

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

        }

    }

    /** creates SQL code and inserts comment into DB connection */

    void writeCommentToDB(String data) {

        try {

          PreparedStatement pstmt;

          pstmt = conn.prepareStatement(

                "INSERT INTO xml_nodes (nodeid, nodetype, " +

                "nodename, parentnodeid, nodedata) VALUES (null, ?, null, ?, ?)");

          // Bind the values to the query

          pstmt.setString(1, "COMMENT");

          pstmt.setLong(2, getElementID());

          pstmt.setString(3, data);

          // Do the insertion

          pstmt.execute();

          pstmt.close();

        } catch (SQLException e) {

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

        }

    }

    /** look up the assigned element id from DB connection */

    private long getAssignedElementID() {

        long assigned_id=0;

        Statement stmt;

        try {

          stmt = conn.createStatement();

          stmt.execute("SELECT xml_nodes_id_seq.currval FROM dual");

          try {

            ResultSet rs = stmt.getResultSet();

            try {

              boolean tableHasRows = rs.next();

              if (tableHasRows) {

                try {

                  assigned_id = rs.getLong(1);

                } catch (SQLException e) {

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

                }

              }

            } catch (SQLException e) {

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

            }

          } catch (SQLException e) {

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

          }

          stmt.close();

        } catch (SQLException e) {

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

        }

        // assign the new ID number

        return assigned_id;

    }

    /** Add a new attribute to this element, or set its value */

    public void setAttribute(String attName, String attValue) {

      if (attName != null) {

        // Enter the attribute in the hash table

        super.setAttribute(attName, attValue);

        // And enter the attribute in the database

        try {

          PreparedStatement pstmt = conn.prepareStatement(

              "INSERT INTO xml_nodes (nodeid, nodetype, " +

              "nodename, nodedata, parentnodeid) VALUES (null, ?, ?, ?, ?)");

          // Bind the values to the query

          pstmt.setString(1, "ATTRIBUTE");

          pstmt.setString(2, attName);

          pstmt.setString(3, attValue);

          pstmt.setLong(4, getElementID());

          // Do the insertion

          pstmt.execute();

          pstmt.close();

        } catch (SQLException e) {

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

        }

      } else {

        System.err.println("Attribute name must not be null!");

      }

    }

    /** Write the element content to the db connection */

    public void writeContentToDB() {

        try {

          PreparedStatement pstmt = conn.prepareStatement(

                "UPDATE xml_nodes SET nodedata = ? WHERE nodeid = ?");

          // Bind the values to the query

          pstmt.setString(1, getContent());

          pstmt.setLong(2, getElementID());

          // Do the update

          pstmt.execute();

          pstmt.close();

        } catch (SQLException e) {

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

        }

    }

}