Metacat

/**

 *        Name: DBSAXHandler.java

 *     Purpose: A Class that handles the SAX XML events as they

 *              are generated from XML documents

 *   Copyright: 2000 Regents of the University of California and the

 *              National Center for Ecological Analysis and Synthesis

 *     Authors: Matt Jones

 *

 *     Version: '$Id: DBSAXHandler.java 133 2000-06-07 22:40:05Z jones $'

 */

package edu.ucsb.nceas.metacat;

import org.xml.sax.*;

import java.sql.*;

import java.util.Stack;

import java.util.EmptyStackException;

// Extensions to the SAX Interfaces for Namespace support.

import oracle.xml.parser.v2.DefaultXMLDocumentHandler;

import oracle.xml.parser.v2.NSName;

import oracle.xml.parser.v2.SAXAttrList;

import oracle.xml.parser.v2.SAXParser;

import oracle.xml.parser.v2.DTD;

/** 

 * A database aware Class implementing callback bethods for the SAX parser to

 * call when processing the XML stream and generating events

 */

public class DBSAXHandler extends DefaultXMLDocumentHandler {

   static int elementNo = 0;

   static String docname = null;

   private String doctype;

   private String systemid;

   private boolean 	debug 	= false;

   private boolean 	stackCreated = false;

   private Stack 	elementStack;

   private Connection	conn = null;

   /** Construct an instance of the handler class 

    *

    * @param conn the JDBC connection to which information is written

    */

   public DBSAXHandler(Connection conn) {

      this.conn = conn;

      // Create the stack for keeping track of element context

      // if it doesn't already exist

      if (!stackCreated) {

        elementStack = new Stack();

        stackCreated = true;

      }

   }

   /** SAX Handler that receives notification of beginning of the document */

   public void startDocument() throws SAXException {

    if (debug) {

      System.out.println("start Document");

    }

    // Create the document node represantation as root

    DBSAXElement documentNode = new DBSAXElement(conn, docname, 0, 0);

    // Add the element to the stack, so that any text data can be 

    // added as it is encountered

    elementStack.push(documentNode);

   }

   /** SAX Handler that receives notification of end of the document */

   public void endDocument() throws SAXException {

    if (debug) {

      System.out.println("end Document");

    }

   }

   /** SAX Handler that receives notification of DTD. Sets the DTD */

   public void setDoctype(DTD dtd) throws SAXException {

     // here is a bug: dtd.getPublicId() and dtd.getSustemId() 

     // always return null.

     docname = dtd.getName();

     doctype = dtd.getPublicId();

     systemid = dtd.getSystemId();

     if (debug) {

       System.out.println("DOCNAME: " + docname);

       System.out.println("DOCTYPE: " + doctype);

       System.out.println("  SYSID: " + systemid);

     }

   }

   /** 

    * SAX Handler that receives notification of end of DTD 

    * All events in DTDHandler about all unparsed entities and the 

    * event in EntityResolver for the DTD file declaration appear 

    * between setDoctype and endDoctype. The rest of parsable external 

    * entities inside DTD file appear later in the elements from where 

    * they are referred to. 

    */

   public void endDoctype() throws SAXException {

     if (debug) {

       System.out.println("end of DOCTYPE");

     }

   }

   /** SAX Handler that is called at the start of each XML element */

   public void startElement(NSName name, SAXAttrList atts) throws SAXException {

      // Use the methods getQualifiedName(), getLocalName(), getNamespace()

      // and getExpandedName() in NSName interface to get Namespace

      // information.

      String qName;

      String localName;

      String nsName;

      String expName;

      DBSAXElement parentElement;

      DBSAXElement currentElement;

      qName = name.getQualifiedName();

      localName = name.getLocalName();

      nsName = name.getNamespace();

      expName = name.getExpandedName();

      elementNo++;

      // Get a reference to the parent element for the id

      long parent_id;

      int nodeIndex;

      try {

        parentElement = (DBSAXElement)elementStack.peek();

        parent_id = parentElement.getElementID();

        nodeIndex = parentElement.incChildNum();

      } catch (EmptyStackException e) {

        parent_id = 0;

        nodeIndex = 0;

      }

      // Document representation that points to the root document node

      if (elementNo == 1) {

        // If no DOCTYPE declaration: docname = root element name 

        if (docname == null)

            docname = localName;

        else if (doctype == null)

            doctype = DBEntityResolver.doctype;

        DBSAXElement documentNode = (DBSAXElement)elementStack.peek();

        documentNode.writeNodename(docname);

        new DBSAXDocument(conn, documentNode.getElementID(), docname, doctype);

      }      

      // Create the current element representation

      currentElement = new DBSAXElement(conn, localName, parent_id, nodeIndex);

      // Add all of the attributes

      for (int i=0; i<atts.getLength(); i++)

      {

         // Use the methods getQualifiedName(), getLocalName(), getNamespace()

         // and getExpandedName() in SAXAttrList interface to get Namespace

         // information.

         qName = atts.getQualifiedName(i);

         localName = atts.getLocalName(i);

         nsName = atts.getNamespace(i);

         expName = atts.getExpandedName(i);

         // You can get the type and value of the attributes either

         // by index or by the Qualified Name.

         String type = atts.getType(qName);

         String value = atts.getValue(qName);

         currentElement.setAttribute(localName, value);

      }      

      // Add the element to the stack, so that any text data can be 

      // added as it is encountered

      elementStack.push(currentElement);

   }

   /** SAX Handler that is called for each XML text node */

   public void characters(char[] cbuf, int start, int len) {

      DBSAXElement currentElement = (DBSAXElement)elementStack.peek();

      int nodeIndex = currentElement.incChildNum();

      String data = new String(cbuf, start, len);

      // Write the content of the element to the database

      currentElement.writeChildNodeToDB("TEXT", null, data, nodeIndex);

   }

   /** 

    * SAX Handler that is called for each XML text node that is Ignorable

    * white space

    */

   public void ignorableWhitespace(char[] cbuf, int start, int len) {

   }

   /** 

    * SAX Handler called once for each comment found: 

    * node that comment may occur before or after the root element.

    * For now works only for comments after the root element. 

    */

   public void comment(String data) throws SAXException {

      DBSAXElement currentElement = (DBSAXElement)elementStack.peek();

      int nodeIndex = currentElement.incChildNum();

      currentElement.writeChildNodeToDB("COMMENT", null, data, nodeIndex);

   }

   /** 

    * SAX Handler called once for each processing instruction found: 

    * node that PI may occur before or after the root element.

    */

   public void processingInstruction(String target, String data) 

          throws SAXException {

      DBSAXElement currentElement = (DBSAXElement)elementStack.peek();

      int nodeIndex = currentElement.incChildNum();

      currentElement.writeChildNodeToDB("PI", target, data, nodeIndex);

   }

   /** SAX Handler that is called at the end of each XML element */

   public void endElement(NSName name) throws SAXException {

      // Use the methods getQualifiedName(), getLocalName(), getNamespace()

      // and getExpandedName() in NSName interface to get Namespace

      // information.

      String expName = name.getExpandedName();

      // Get the element from the stack

      DBSAXElement currentElement = (DBSAXElement)elementStack.pop();

   }

   /** Debug routine */

   private void db(int flag) {

     if (debug) {

       System.err.println("DEBUG POSITION " + flag);

     }

   }   

}