DebugHandler

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 * Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id$
 */
package org.exolab.castor.xml;

import java.io.PrintWriter;
import java.io.Writer;

import org.xml.sax.AttributeList;
import org.xml.sax.DocumentHandler;
import org.xml.sax.Locator;

/**
 * A Simple SAX1 DocumentHandler that intercepts SAX events and prints them to the console. This
 * class is not used during normal Castor operation, but exists so that during debugging one can
 * replace a normal DocumentHandler with this one (which will proxy to the correct DocumentHandler).
 * <p>
 * FIXME: As Castor moves internally to the SAX2 interface, this class should also be updated for
 * SAX2.
 *
 * @author <a href="mailto:kvisco@intalio.com">Keith Visco</a>
 * @version $Revision$ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
 */
public class DebugHandler implements DocumentHandler {

  /** The writer to report events to. */
  private Writer _out = null;
  /** The DocumentHandler to forward events to. */
  private DocumentHandler _handler = null;

  /**
   * Creates a new DebugHandler which forwards events to the given document handler.
   *
   * @param handler the DocumentHandler to forward events to
   */
  public DebugHandler(final DocumentHandler handler) {
    this(handler, null);
  }

  /**
   * Creates a new DebugHandler which forwards events to the given document handler.
   *
   * @param handler the DocumentHandler to forward events to
   * @param out the Writer to print debug information to
   */
  public DebugHandler(final DocumentHandler handler, final Writer out) {
    if (out == null) {
      this._out = new PrintWriter(System.out);
    }
    this._handler = handler;
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#characters(char[], int, int) request to
   * the proxy that is provided, printing debugging information before doing the proxy.
   */
  public void characters(final char[] ch, final int start, final int length)
      throws org.xml.sax.SAXException {
    try {
      _out.write(ch, start, length);
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.characters(ch, start, length);
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#endDocument() request to the proxy that
   * is provided, printing debugging information before doing the proxy.
   */
  public void endDocument() throws org.xml.sax.SAXException {
    try {
      _out.write("#endDocument\n");
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.endDocument();
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#endElement(String) request to the proxy
   * that is provided, printing debugging information before doing the proxy.
   */
  public void endElement(final String name) throws org.xml.sax.SAXException {
    try {
      _out.write("</");
      _out.write(name);
      _out.write(">\n");
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.endElement(name);
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#ignorableWhitespace(char[], int, int)
   * request to the proxy that is provided, printing debugging information before doing the proxy.
   */
  public void ignorableWhitespace(final char[] ch, final int start, final int length)
      throws org.xml.sax.SAXException {
    if (_handler != null) {
      _handler.ignorableWhitespace(ch, start, length);
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#processingInstruction(String, String)
   * request to the proxy that is provided, printing debugging information before doing the proxy.
   */
  public void processingInstruction(final String target, final String data)
      throws org.xml.sax.SAXException {
    try {
      _out.write("--#processingInstruction\n");
      _out.write("target: ");
      _out.write(target);
      _out.write(" data: ");
      _out.write(data);
      _out.write('\n');
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.processingInstruction(target, data);
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#setDocumentLocator(Locator) request to
   * the proxy that is provided, printing debugging information before doing the proxy.
   */
  public void setDocumentLocator(final Locator locator) {
    if (_handler != null) {
      _handler.setDocumentLocator(locator);
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#startDocument() request to the proxy that
   * is provided, printing debugging information before doing the proxy.
   */
  public void startDocument() throws org.xml.sax.SAXException {
    try {
      _out.write("#startDocument\n");
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.startDocument();
    }
  }

  /**
   * {@inheritDoc} Proxies the org.sax.xml.DocumentHandler#startElement(String, AttributeList)
   * request to the proxy that is provided, printing debugging information before doing the proxy.
   */
  public void startElement(final String name, final AttributeList atts)
      throws org.xml.sax.SAXException {
    try {
      _out.write('<');
      _out.write(name);
      if (atts != null && atts.getLength() > 0) {
        for (int i = 0; i < atts.getLength(); i++) {
          _out.write(' ');
          _out.write(atts.getName(i));
          _out.write("=\"");
          _out.write(atts.getValue(i));
          _out.write("\"");
        }
      }
      _out.write(">\n");
      _out.flush();
    } catch (java.io.IOException ioe) {
      ioe.printStackTrace();
    }

    if (_handler != null) {
      _handler.startElement(name, atts);
    }
  }

}