/* ========================================================================
* JCommon : a free general purpose class library for the Java(tm) platform
* ========================================================================
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ---------------------------
* AbstractXmlReadHandler.java
* ---------------------------
* (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
*
* Original Author: Thomas Morgner;
* Contributor(s): David Gilbert (for Object Refinery Limited);
*
* $Id: AbstractXmlReadHandler.java,v 1.5 2008/09/10 09:20:16 mungady Exp $
*
* Changes (from 25-Nov-2003)
* --------------------------
* 25-Nov-2003 : Added Javadocs (DG);
*
*/
package org.jfree.xml.parser;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.jfree.util.Log;
/**
* A base class for implementing an {@link XmlReadHandler}.
*/
public abstract class AbstractXmlReadHandler implements XmlReadHandler {
/** The root handler. */
private RootXmlReadHandler rootHandler;
/** The tag name. */
private String tagName;
/** A flag indicating the first call. */
private boolean firstCall = true;
/**
* Creates a new handler.
*/
public AbstractXmlReadHandler() {
}
/**
* Initialises the handler.
*
* @param rootHandler the root handler.
* @param tagName the tag name.
*/
public void init(final RootXmlReadHandler rootHandler, final String tagName) {
if (rootHandler == null) {
throw new NullPointerException("Root handler must not be null");
}
if (tagName == null) {
throw new NullPointerException("Tag name must not be null");
}
this.rootHandler = rootHandler;
this.tagName = tagName;
}
/**
* This method is called at the start of an element.
*
* @param tagName the tag name.
* @param attrs the attributes.
*
* @throws SAXException if there is a parsing error.
* @throws XmlReaderException if there is a reader error.
*/
public final void startElement(final String tagName, final Attributes attrs)
throws XmlReaderException, SAXException {
if (this.firstCall) {
if (!this.tagName.equals(tagName)) {
throw new SAXException("Expected <" + this.tagName + ">, found <" + tagName + ">");
}
this.firstCall = false;
startParsing(attrs);
}
else {
final XmlReadHandler childHandler = getHandlerForChild(tagName, attrs);
if (childHandler == null) {
Log.warn ("Unknown tag <" + tagName + ">");
return;
}
childHandler.init(getRootHandler(), tagName);
this.rootHandler.recurse(childHandler, tagName, attrs);
}
}
/**
* This method is called to process the character data between element tags.
*
* @param ch the character buffer.
* @param start the start index.
* @param length the length.
*
* @throws SAXException if there is a parsing error.
*/
public void characters(final char[] ch, final int start, final int length) throws SAXException {
// nothing required
}
/**
* This method is called at the end of an element.
*
* @param tagName the tag name.
*
* @throws SAXException if there is a parsing error.
*/
public final void endElement(final String tagName) throws SAXException {
if (this.tagName.equals(tagName)) {
try {
doneParsing();
this.rootHandler.unwind(tagName);
}
catch (XmlReaderException xre) {
throw new SAXException(xre);
}
}
}
/**
* Starts parsing.
*
* @param attrs the attributes.
*
* @throws SAXException if there is a parsing error.
* @throws XmlReaderException ?
*/
protected void startParsing(final Attributes attrs)
throws SAXException, XmlReaderException {
// nothing required
}
/**
* Done parsing.
*
* @throws SAXException if there is a parsing error.
* @throws XmlReaderException if there is a reader error.
*/
protected void doneParsing() throws SAXException, XmlReaderException {
// nothing required
}
/**
* Returns the handler for a child element.
*
* @param tagName the tag name.
* @param atts the attributes.
*
* @return the handler or null, if the tagname is invalid.
*
* @throws SAXException if there is a parsing error.
* @throws XmlReaderException if there is a reader error.
*/
protected XmlReadHandler getHandlerForChild(final String tagName, final Attributes atts)
throws XmlReaderException, SAXException {
return null;
}
/**
* Returns the tag name.
*
* @return the tag name.
*/
public String getTagName() {
return this.tagName;
}
/**
* Returns the root handler for the parsing.
*
* @return the root handler.
*/
public RootXmlReadHandler getRootHandler() {
return this.rootHandler;
}
}