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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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