001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
025 * in the United States and other countries.]
026 *
027 * -----------------
028 * ValueHandler.java
029 * -----------------
030 * (C) Copyright 2003-2008, by Object Refinery Limited and Contributors.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   Luke Quinane;
034 *
035 * Changes
036 * -------
037 * 23-Jan-2003 : Version 1 (DG);
038 * 25-Nov-2003 : Patch to handle 'NaN' values (DG);
039 *
040 */
041
042package org.jfree.data.xml;
043
044import org.xml.sax.Attributes;
045import org.xml.sax.SAXException;
046import org.xml.sax.helpers.DefaultHandler;
047
048/**
049 * A handler for reading a 'Value' element.
050 */
051public class ValueHandler extends DefaultHandler implements DatasetTags {
052
053    /** The root handler. */
054    private RootHandler rootHandler;
055
056    /** The item handler. */
057    private ItemHandler itemHandler;
058
059    /** Storage for the current CDATA */
060    private StringBuffer currentText;
061
062    /**
063     * Creates a new value handler.
064     *
065     * @param rootHandler  the root handler.
066     * @param itemHandler  the item handler.
067     */
068    public ValueHandler(RootHandler rootHandler, ItemHandler itemHandler) {
069        this.rootHandler = rootHandler;
070        this.itemHandler = itemHandler;
071        this.currentText = new StringBuffer();
072    }
073
074    /**
075     * The start of an element.
076     *
077     * @param namespaceURI  the namespace.
078     * @param localName  the element name.
079     * @param qName  the element name.
080     * @param atts  the attributes.
081     *
082     * @throws SAXException for errors.
083     */
084    public void startElement(String namespaceURI,
085                             String localName,
086                             String qName,
087                             Attributes atts) throws SAXException {
088
089        if (qName.equals(VALUE_TAG)) {
090            // no attributes to read
091            clearCurrentText();
092        }
093        else {
094            throw new SAXException("Expecting <Value> but found " + qName);
095        }
096
097    }
098
099    /**
100     * The end of an element.
101     *
102     * @param namespaceURI  the namespace.
103     * @param localName  the element name.
104     * @param qName  the element name.
105     *
106     * @throws SAXException for errors.
107     */
108    public void endElement(String namespaceURI,
109                           String localName,
110                           String qName) throws SAXException {
111
112        if (qName.equals(VALUE_TAG)) {
113            Number value;
114            try {
115                value = Double.valueOf(this.currentText.toString());
116                if (((Double) value).isNaN()) {
117                    value = null;
118                }
119            }
120            catch (NumberFormatException e1) {
121                value = null;
122            }
123            this.itemHandler.setValue(value);
124            this.rootHandler.popSubHandler();
125        }
126        else {
127            throw new SAXException("Expecting </Value> but found " + qName);
128        }
129
130    }
131
132    /**
133     * Receives some (or all) of the text in the current element.
134     *
135     * @param ch  character buffer.
136     * @param start  the start index.
137     * @param length  the length of the valid character data.
138     */
139    public void characters(char[] ch, int start, int length) {
140        if (this.currentText != null) {
141            this.currentText.append(String.copyValueOf(ch, start, length));
142        }
143    }
144
145    /**
146     * Returns the current text of the textbuffer.
147     *
148     * @return The current text.
149     */
150    protected String getCurrentText() {
151        return this.currentText.toString();
152    }
153
154    /**
155     * Removes all text from the textbuffer at the end of a CDATA section.
156     */
157    protected void clearCurrentText() {
158        this.currentText.delete(0, this.currentText.length());
159    }
160
161}