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/**
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 *        Name: DBSAXElement.java
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 *     Purpose: A Class that represents an XML element and its contents
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 *   Copyright: 2000 Regents of the University of California and the
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 *              National Center for Ecological Analysis and Synthesis
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 *     Authors: Matt Jones
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 *
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 *     Version: '$Id: DBSAXElement.java 51 2000-04-17 23:06:07Z jones $'
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 */
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package edu.ucsb.nceas.metacat;
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import java.sql.*;
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import java.io.IOException;
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import java.util.Hashtable;
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import java.util.Enumeration;
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/** 
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 * A Class that represents an XML element and its contents and
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 * can write its own representation to a database connection
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 */
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public class DBSAXElement extends BasicElement {
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    private Connection		conn;
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    /** 
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     * Construct a new element instance
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     *
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     * @param conn the JDBC Connection to which all information is written
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     * @param tagname the name of the element
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     * @param parent_id the parent id number for this element
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     */
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    public DBSAXElement (Connection conn, String tagname, 
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                         long parent_id) {
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      super(tagname, parent_id);
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      this.conn = conn;
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      writeElementToDB();
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    }
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    /** creates SQL code and inserts new element into DB connection */
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    private void writeElementToDB() {
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        try {
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          conn.setAutoCommit(false);
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          PreparedStatement pstmt;
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          if (getParentID() != 0) {
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            pstmt = conn.prepareStatement(
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                "INSERT INTO xml_nodes (nodeid, nodetype, " +
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                "nodename, parentnodeid) VALUES (null, ?, ?, ?)");
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          } else {
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            pstmt = conn.prepareStatement(
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                "INSERT INTO xml_nodes (nodeid, nodetype, nodename) " +
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                "VALUES (null, ?, ?)");
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          }
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          // Bind the values to the query
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          pstmt.setString(1, "ELEMENT");
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          pstmt.setString(2, getTagName());
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          if (getParentID() != 0) {
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            pstmt.setLong(3, getParentID());
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          }
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          // Do the insertion
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          pstmt.execute();
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          pstmt.close();
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          setElementID(getAssignedElementID());
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          conn.commit();
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          conn.setAutoCommit(true);
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        } catch (SQLException e) {
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          System.out.println(e.getMessage());
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        }
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    }
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    /** look up the assigned element id from DB connection */
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    private long getAssignedElementID() {
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        long assigned_id=0;
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        Statement stmt;
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        try {
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          stmt = conn.createStatement();
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          stmt.execute("SELECT xml_nodes_id_seq.currval FROM dual");
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          try {
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            ResultSet rs = stmt.getResultSet();
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            try {
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              boolean tableHasRows = rs.next();
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              if (tableHasRows) {
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                try {
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                  assigned_id = rs.getLong(1);
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                } catch (SQLException e) {
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                  System.out.println("Error with getInt: " + e.getMessage());
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                }
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              }
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            } catch (SQLException e) {
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              System.out.println("Error with next: " + e.getMessage());
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            }
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          } catch (SQLException e) {
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            System.out.println("Error with getrset: " + e.getMessage());
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          }
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          stmt.close();
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        } catch (SQLException e) {
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          System.out.println("Error getting id: " + e.getMessage());
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        }
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        // assign the new ID number
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        return assigned_id;
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    }
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    /** Add a new attribute to this element, or set its value */
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    public void setAttribute(String attName, String attValue) {
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      if (attName != null) {
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        // Enter the attribute in the hash table
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        super.setAttribute(attName, attValue);
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        // And enter the attribute in the database
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        try {
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          PreparedStatement pstmt = conn.prepareStatement(
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              "INSERT INTO xml_nodes (nodeid, nodetype, " +
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              "nodename, nodedata, parentnodeid) VALUES (null, ?, ?, ?, ?)");
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          // Bind the values to the query
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          pstmt.setString(1, "ATTRIBUTE");
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          pstmt.setString(2, attName);
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          pstmt.setString(3, attValue);
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          pstmt.setLong(4, getElementID());
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          // Do the insertion
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          pstmt.execute();
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          pstmt.close();
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        } catch (SQLException e) {
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          System.out.println(e.getMessage());
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        }
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      } else {
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        System.err.println("Attribute name must not be null!");
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      }
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    }
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    /** Write the element content to the db connection */
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    public void writeContentToDB() {
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        try {
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          PreparedStatement pstmt = conn.prepareStatement(
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                "UPDATE xml_nodes SET nodedata = ? WHERE nodeid = ?");
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          // Bind the values to the query
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          pstmt.setString(1, getContent());
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          pstmt.setLong(2, getElementID());
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          // Do the update
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          pstmt.execute();
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          pstmt.close();
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        } catch (SQLException e) {
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          System.out.println(e.getMessage());
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        }
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    }
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}
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