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/**
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* Name: DBSAXHandler.java
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* Purpose: A Class that handles the SAX XML events as they
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* are generated from XML documents
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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 org.xml.sax.*;
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import java.sql.*;
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import java.util.Stack;
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import java.util.EmptyStackException;
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// Extensions to the SAX Interfaces for Namespace support.
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import oracle.xml.parser.v2.DefaultXMLDocumentHandler;
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import oracle.xml.parser.v2.NSName;
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import oracle.xml.parser.v2.SAXAttrList;
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import oracle.xml.parser.v2.SAXParser;
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/**
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* A database aware Class implementing callback bethods for the SAX parser to
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* call when processing the XML stream and generating events
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*/
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public class DBSAXHandler extends DefaultXMLDocumentHandler
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{
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private boolean debug = false;
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private boolean stackCreated = false;
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private Stack elementStack;
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private Connection conn = null;
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/** Construct an instance of the handler class
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*
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* @param conn the JDBC connection to which information is written
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*/
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public DBSAXHandler(Connection conn)
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{
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this.conn = conn;
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// Create the stack for keeping track of element context
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// if it doesn't already exist
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if (!stackCreated) {
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elementStack = new Stack();
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stackCreated = true;
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}
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}
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/** SAX Handler that is called at the start of each XML element */
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public void startElement(NSName name, SAXAttrList atts) throws SAXException
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{
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// Use the methods getQualifiedName(), getLocalName(), getNamespace()
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// and getExpandedName() in NSName interface to get Namespace
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// information.
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String qName;
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String localName;
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String nsName;
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String expName;
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DBSAXElement parentElement;
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DBSAXElement currentElement;
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qName = name.getQualifiedName();
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localName = name.getLocalName();
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nsName = name.getNamespace();
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expName = name.getExpandedName();
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// Get a reference to the parent element for the id
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long parent_id;
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try {
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parentElement = (DBSAXElement)elementStack.peek();
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parent_id = parentElement.getElementID();
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} catch (EmptyStackException e) {
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parent_id = 0;
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}
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// Create the current element representation
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currentElement = new DBSAXElement(conn, localName, parent_id);
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// Add all of the attributes
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for (int i=0; i<atts.getLength(); i++)
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{
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// Use the methods getQualifiedName(), getLocalName(), getNamespace()
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// and getExpandedName() in SAXAttrList interface to get Namespace
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// information.
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qName = atts.getQualifiedName(i);
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localName = atts.getLocalName(i);
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nsName = atts.getNamespace(i);
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expName = atts.getExpandedName(i);
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// You can get the type and value of the attributes either
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// by index or by the Qualified Name.
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String type = atts.getType(qName);
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String value = atts.getValue(qName);
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currentElement.setAttribute(localName, value);
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}
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// Add the element to the stack, so that any text data can be
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// added as it is encountered
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elementStack.push(currentElement);
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}
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/** SAX Handler that is called for each XML text node */
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public void characters(char[] cbuf, int start, int len)
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{
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DBSAXElement currentElement = (DBSAXElement)elementStack.peek();
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currentElement.appendContent(cbuf,start,len);
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}
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/**
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* SAX Handler that is called for each XML text node that is Ignorable
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* white space
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*/
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public void ignorableWhitespace(char[] cbuf, int start, int len)
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{
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}
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/** SAX Handler that is called at the end of each XML element */
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public void endElement(NSName name) throws SAXException
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{
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// Use the methods getQualifiedName(), getLocalName(), getNamespace()
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// and getExpandedName() in NSName interface to get Namespace
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// information.
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String expName = name.getExpandedName();
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// Get the element from the stack
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DBSAXElement currentElement = (DBSAXElement)elementStack.pop();
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// Write the content of the element to the database
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currentElement.writeContentToDB();
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}
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/** Debug routine */
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private void db(int flag) {
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if (debug) {
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System.err.println("DEBUG POSITION " + flag);
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}
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}
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}
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