001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, 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 2003-2005, by Object Refinery Limited and Contributors.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   Luke Quinane;
034     *
035     * $Id: ValueHandler.java,v 1.3.2.1 2005/10/25 21:36:10 mungady Exp $
036     *
037     * Changes
038     * -------
039     * 23-Jan-2003 : Version 1 (DG);
040     * 25-Nov-2003 : Patch to handle 'NaN' values (DG);
041     *
042     */
043    
044    package org.jfree.data.xml;
045    
046    import org.xml.sax.Attributes;
047    import org.xml.sax.SAXException;
048    import org.xml.sax.helpers.DefaultHandler;
049    
050    /**
051     * A handler for reading a 'Value' element.
052     */
053    public class ValueHandler extends DefaultHandler implements DatasetTags {
054    
055        /** The root handler. */
056        private RootHandler rootHandler;
057    
058        /** The item handler. */
059        private ItemHandler itemHandler;
060    
061        /** Storage for the current CDATA */
062        private StringBuffer currentText;
063    
064        /**
065         * Creates a new value handler.
066         *
067         * @param rootHandler  the root handler.
068         * @param itemHandler  the item handler.
069         */
070        public ValueHandler(RootHandler rootHandler, ItemHandler itemHandler) {
071            this.rootHandler = rootHandler;
072            this.itemHandler = itemHandler;
073            this.currentText = new StringBuffer();
074        }
075    
076        /**
077         * The start of an element.
078         *
079         * @param namespaceURI  the namespace.
080         * @param localName  the element name.
081         * @param qName  the element name.
082         * @param atts  the attributes.
083         *
084         * @throws SAXException for errors.
085         */
086        public void startElement(String namespaceURI,
087                                 String localName,
088                                 String qName,
089                                 Attributes atts) throws SAXException {
090    
091            if (qName.equals(VALUE_TAG)) {
092                // no attributes to read
093                clearCurrentText();
094            }
095            else {
096                throw new SAXException("Expecting <Value> but found " + qName);
097            }
098    
099        }
100    
101        /**
102         * The end of an element.
103         *
104         * @param namespaceURI  the namespace.
105         * @param localName  the element name.
106         * @param qName  the element name.
107         *
108         * @throws SAXException for errors.
109         */
110        public void endElement(String namespaceURI,
111                               String localName,
112                               String qName) throws SAXException {
113    
114            if (qName.equals(VALUE_TAG)) {
115                Number value;
116                try {
117                    value = Double.valueOf(this.currentText.toString());
118                    if (((Double) value).isNaN()) {
119                        value = null;
120                    }
121                } 
122                catch (NumberFormatException e1) {
123                    value = null;
124                }
125                this.itemHandler.setValue(value);
126                this.rootHandler.popSubHandler();
127            }
128            else {
129                throw new SAXException("Expecting </Value> but found " + qName);
130            }
131    
132        }
133    
134        /**
135         * Receives some (or all) of the text in the current element.
136         *
137         * @param ch  character buffer.
138         * @param start  the start index.
139         * @param length  the length of the valid character data.
140         */
141        public void characters(char[] ch, int start, int length) {
142            if (this.currentText != null) {
143                this.currentText.append(String.copyValueOf(ch, start, length));
144            }
145        }
146    
147        /**
148         * Returns the current text of the textbuffer.
149         *
150         * @return The current text.
151         */
152        protected String getCurrentText() {
153            return this.currentText.toString();
154        }
155    
156        /**
157         * Removes all text from the textbuffer at the end of a CDATA section.
158         */
159        protected void clearCurrentText() {
160            this.currentText.delete(0, this.currentText.length());
161        }
162    
163    }