Metacat

/**

 *      Name: DBSAXNode.java

 *   Purpose: A Class that represents an XML node 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: DBSAXNode.java 168 2000-06-16 03:20:41Z 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 node and its contents and

 * can write its own representation to a database connection

 */

public class DBSAXNode extends BasicNode {

  private Connection		conn;

  /** 

   * Construct a new node instance for DOCUMENT nodes

   *

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

   * @param tagname the name of the node

   */

  public DBSAXNode (Connection conn, String tagname) {

    super(tagname);

    this.conn = conn;

    writeChildNodeToDB("DOCUMENT", tagname, null);

    setNodeID(getAssignedNodeID());

    setRootNodeID(getNodeID());

  }

  /** 

   * Construct a new node instance for ELEMENT nodes

   *

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

   * @param tagname the name of the node

   * @param parentNode the parent node for this node being created

   */

  public DBSAXNode (Connection conn, String tagname, 

                    DBSAXNode parentNode, DBSAXNode rootNode, DBSAXDocument currentDocument) {

    super(tagname);

    setParentID(parentNode.getNodeID());

    setRootNodeID(rootNode.getNodeID());

    setDocID(currentDocument.getDocID());

    setNodeIndex(parentNode.incChildNum());

    this.conn = conn;

    writeChildNodeToDB("ELEMENT", getTagName(), null);

    setNodeID(getAssignedNodeID());

  }

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

  public void writeChildNodeToDB(String nodetype, String nodename,

                                 String data) {

    try {

      PreparedStatement pstmt;

      if (nodetype == "DOCUMENT") {

        pstmt = conn.prepareStatement(

            "INSERT INTO xml_nodes " +

            "(nodeid, nodetype, nodename) " +

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

      } else {

        pstmt = conn.prepareStatement(

            "INSERT INTO xml_nodes " +

            "(nodeid, nodetype, nodename, " +

            "parentnodeid, rootnodeid, docid, nodedata, nodeindex) " +

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

      }

      // Bind the values to the query

      pstmt.setString(1, nodetype);

      pstmt.setString(2, nodename);

      if (nodetype != "DOCUMENT") {

        if (nodetype == "ELEMENT") {

          pstmt.setLong(3, getParentID());

          pstmt.setLong(4, getRootNodeID());

          pstmt.setString(5, getDocID());

          pstmt.setString(6, data);

          pstmt.setInt(7, getNodeIndex());

        } else {

          pstmt.setLong(3, getNodeID());

          pstmt.setLong(4, getRootNodeID());

          pstmt.setString(5, getDocID());

          pstmt.setString(6, data);

          pstmt.setInt(7, incChildNum());

        }

      }

      // Do the insertion

      pstmt.execute();

      pstmt.close();

    } catch (SQLException e) {

      System.err.println("Error inserting node: (" + nodetype + ", " +

                                                     nodename + ", " + 

                                                     data + ")" );

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

    }

  }

  /** 

   * creates SQL code to put nodename for the document node 

   * into DB connection 

   */

  public void writeNodename(String nodename) {

      try {

        PreparedStatement pstmt;

        pstmt = conn.prepareStatement(

              "UPDATE xml_nodes set nodename = ? " +

              "WHERE nodeid = ?");

        // Bind the values to the query

        pstmt.setString(1, nodename);

        pstmt.setLong(2, getNodeID());

        // Do the insertion

        pstmt.execute();

        pstmt.close();

      } catch (SQLException e) {

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

      }

  }

  /** 

   * creates SQL code to put root node id for the document node 

   * into DB connection 

   */

  public void writeRootNodeID(long rootnode_id) {

      try {

        PreparedStatement pstmt;

        pstmt = conn.prepareStatement(

              "UPDATE xml_nodes set rootnodeid = ? " +

              "WHERE nodeid = ?");

        // Bind the values to the query

        pstmt.setLong(1, rootnode_id);

        pstmt.setLong(2, getNodeID());

        // Do the insertion

        pstmt.execute();

        pstmt.close();

      } catch (SQLException e) {

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

      }

  }

  /** 

   * creates SQL code to put doc ID for the document node and for comment/PI nodes under document node

   * into DB connection 

   */

  public void writeDocID(String doc_id) {

      try {

        PreparedStatement pstmt;

        pstmt = conn.prepareStatement(

              "UPDATE xml_nodes set docid = ? " +

              "WHERE nodeid = ?");

        // Bind the values to the query

        pstmt.setString(1, doc_id);

        pstmt.setLong(2, getNodeID());

        // Do the insertion

        pstmt.execute();

        pstmt.close();

        // for comments and PI on the top

        pstmt = conn.prepareStatement(

              "UPDATE xml_nodes set docid = ? " +

              "WHERE parentnodeid = ?");

        // Bind the values to the query

        pstmt.setString(1, doc_id);

        pstmt.setLong(2, getNodeID());

        // Do the insertion

        pstmt.execute();

        pstmt.close();

      } catch (SQLException e) {

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

      }

  }

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

  private long getAssignedNodeID() {

      long assigned_id=0;

      Statement stmt;

      try {

        stmt = conn.createStatement();

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

        ResultSet rs = stmt.getResultSet();

        boolean tableHasRows = rs.next();

        if (tableHasRows) {

          assigned_id = rs.getLong(1);

        }

        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 node, 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

      writeChildNodeToDB("ATTRIBUTE", attName, attValue);

    } else {

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

    }

  }

}