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/**
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* Name: ReaderElement.java
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* Purpose: A Class that represents an XML element and its contents,
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* and can build itself from a database connection
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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: '$Id$'
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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.Vector;
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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,
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* and can build itself from a database connection
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*/
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public class ReaderElement extends BasicElement {
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private Connection conn;
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private Vector children;
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/**
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* Construct a new ReaderElement instance
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*
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* @param conn the database connection to use to initialize
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*/
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public ReaderElement (Connection conn) {
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this.conn = conn;
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this.children = new Vector();
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}
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/**
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* Construct a new ReaderElement instance
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*
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* @param conn the database connection to use to initialize
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* @param nodeid the element_id for the node to be created
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*/
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public ReaderElement (Connection conn, long nodeid) {
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this(conn);
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//Lookup data for self
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setElementInfo(nodeid);
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//Create child nodes (elements or attributes)
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setChildrenNodes(nodeid);
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}
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/**
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* Construct a new ReaderElement instance
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*
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* @param conn the database connection to use to initialize
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* @param nodeid the element_id for the node to be created
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* @param parentnodeid the id of the parent node
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* @param nodename the name of the element
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* @param nodedata the text content of the node
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*/
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public ReaderElement (Connection conn, long nodeid, long parentnodeid,
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String nodename, String nodedata) {
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this(conn);
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setElementID(nodeid);
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setParentID(parentnodeid);
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setTagName(nodename);
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appendContent(nodedata);
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// Create child nodes (elements or attributes)
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setChildrenNodes(nodeid);
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}
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/** Look up the info needed to construct this element from the DB */
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private void setElementInfo(long nodeid) {
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long element_id=0;
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long parentnodeid=0;
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String nodetype=null;
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String nodename=null;
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String nodedata=null;
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PreparedStatement pstmt;
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try {
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pstmt =
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conn.prepareStatement("SELECT nodeid,parentnodeid,nodetype, " +
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"nodename,nodedata FROM xml_nodes WHERE nodeid = ?");
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// Bind the values to the query
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pstmt.setLong(1, nodeid);
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pstmt.execute();
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try {
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ResultSet rs = pstmt.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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element_id = rs.getLong(1);
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parentnodeid = rs.getLong(2);
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nodetype = rs.getString(3);
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nodename = rs.getString(4);
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nodedata = rs.getString(5);
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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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pstmt.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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if (nodetype.equals("ELEMENT")) {
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setElementID(element_id);
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setParentID(parentnodeid);
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setTagName(nodename);
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appendContent(nodedata);
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}
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}
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/** Look up each child node from the DB and and create it */
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private void setChildrenNodes(long nodeid) {
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long element_id=0;
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long parentnodeid=0;
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String nodetype=null;
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String nodename=null;
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String nodedata=null;
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PreparedStatement pstmt;
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try {
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pstmt =
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conn.prepareStatement("SELECT nodeid,parentnodeid,nodetype, " +
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"nodename,nodedata FROM xml_nodes WHERE parentnodeid = ?");
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// Bind the values to the query
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pstmt.setLong(1, nodeid);
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pstmt.execute();
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try {
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ResultSet rs = pstmt.getResultSet();
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try {
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boolean tableHasRows = rs.next();
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while (tableHasRows) {
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try {
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element_id = rs.getLong(1);
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parentnodeid = rs.getLong(2);
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nodetype = rs.getString(3);
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nodename = rs.getString(4);
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nodedata = rs.getString(5);
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if (nodetype.equals("ELEMENT")) {
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ReaderElement child = new ReaderElement(conn,
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element_id,parentnodeid,nodename,nodedata);
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children.add(child);
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} else if (nodetype.equals("ATTRIBUTE")) {
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setAttribute(nodename,nodedata);
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}
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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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// Advance to the next record in the cursor
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tableHasRows = rs.next();
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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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pstmt.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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}
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/**
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* String representation for display purposes (recursively descends through
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* children to create an XML subtree)
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*/
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public String toString ()
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{
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StringBuffer value = new StringBuffer();
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value.append('<');
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value.append(getTagName());
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value.append(getAttributes().toString());
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value.append('>');
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// Process children recursively here
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// Or do it in ReaderElement using a stack so we don;t have the
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// whole thing in memory at once?
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ReaderElement child = null;
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Enumeration e = children.elements();
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while (e.hasMoreElements()) {
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child = (ReaderElement)e.nextElement();
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value.append(child);
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}
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String cont = getContent();
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if (!cont.equals("null")) {
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value.append(cont);
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}
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value.append("</");
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value.append(getTagName());
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value.append('>');
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return value.toString();
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}
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}
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