RootXmlWriteHandler


1   /* ========================================================================
2    * JCommon : a free general purpose class library for the Java(tm) platform
3    * ========================================================================
4    *
5    * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6    * 
7    * Project Info:  http://www.jfree.org/jcommon/index.html
8    *
9    * This library is free software; you can redistribute it and/or modify it 
10   * under the terms of the GNU Lesser General Public License as published by 
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12   * (at your option) any later version.
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14   * This library is distributed in the hope that it will be useful, but 
15   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
16   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
17   * License for more details.
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21   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
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23   *
24   * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
25   * in the United States and other countries.]
26   * 
27   * ------------------------
28   * RootXmlWriteHandler.java
29   * ------------------------
30   * (C) Copyright 2002-2005, by Object Refinery Limited.
31   *
32   * Original Author:  Peter Becker;
33   * Contributor(s):   -;
34   *
35   * $Id: RootXmlWriteHandler.java,v 1.5 2005/10/18 13:35:06 mungady Exp $
36   *
37   * Changes
38   * -------
39   * 23-Dec-2003 : Added missing Javadocs (DG);
40   *
41   */
42  package org.jfree.xml.writer;
43  
44  import java.awt.BasicStroke  ;
45  import java.awt.Color  ;
46  import java.awt.Font  ;
47  import java.awt.GradientPaint  ;
48  import java.awt.Insets  ;
49  import java.awt.Paint  ;
50  import java.awt.RenderingHints  ;
51  import java.awt.Stroke  ;
52  import java.awt.geom.Point2D  ;
53  import java.awt.geom.Rectangle2D  ;
54  import java.io.IOException  ;
55  import java.util.ArrayList  ;
56  import java.util.LinkedList  ;
57  import java.util.List  ;
58  import java.util.Stack  ;
59  import java.util.Vector  ;
60  
61  import org.jfree.util.ObjectUtilities;
62  import org.jfree.xml.util.ManualMappingDefinition;
63  import org.jfree.xml.util.MultiplexMappingDefinition;
64  import org.jfree.xml.util.MultiplexMappingEntry;
65  import org.jfree.xml.util.ObjectFactory;
66  import org.jfree.xml.util.SimpleObjectFactory;
67  import org.jfree.xml.writer.coretypes.BasicStrokeWriteHandler;
68  import org.jfree.xml.writer.coretypes.ColorWriteHandler;
69  import org.jfree.xml.writer.coretypes.FontWriteHandler;
70  import org.jfree.xml.writer.coretypes.GenericWriteHandler;
71  import org.jfree.xml.writer.coretypes.GradientPaintWriteHandler;
72  import org.jfree.xml.writer.coretypes.InsetsWriteHandler;
73  import org.jfree.xml.writer.coretypes.ListWriteHandler;
74  import org.jfree.xml.writer.coretypes.Point2DWriteHandler;
75  import org.jfree.xml.writer.coretypes.Rectangle2DWriteHandler;
76  import org.jfree.xml.writer.coretypes.RenderingHintsWriteHandler;
77  
78  /**
79   * A root handler for writing objects to XML format.
80   */
81  public abstract class RootXmlWriteHandler {
82  
83      /** A map containg the manual mappings. */
84      private SimpleObjectFactory classToHandlerMapping;
85  
86      /**
87       * Creates a new RootXmlWrite handler with the default mappings enabled.
88       */
89      public RootXmlWriteHandler() {
90          this.classToHandlerMapping = new SimpleObjectFactory();
91  
92          // set up handling for Paint objects
93          final MultiplexMappingEntry[] paintEntries = new MultiplexMappingEntry[2];
94          paintEntries[0] = new MultiplexMappingEntry("color", Color  .class.getName());
95          paintEntries[1] = new MultiplexMappingEntry("gradientPaint", GradientPaint  .class.getName());
96          addMultiplexMapping(Paint  .class, "type", paintEntries);
97          addManualMapping(GradientPaint  .class, GradientPaintWriteHandler.class);
98          addManualMapping(Color  .class, ColorWriteHandler.class);
99  
100         // set up handling for Point2D objects
101         final MultiplexMappingEntry[] point2DEntries = new MultiplexMappingEntry[2];
102         point2DEntries[0] = new MultiplexMappingEntry("float", Point2D.Float  .class.getName());
103         point2DEntries[1] = new MultiplexMappingEntry("double", Point2D.Double  .class.getName());
104         addMultiplexMapping(Point2D  .class, "type", point2DEntries);
105         addManualMapping(Point2D.Float  .class, Point2DWriteHandler.class);
106         addManualMapping(Point2D.Double  .class, Point2DWriteHandler.class);
107 
108         // set up handling for Stroke objects
109         final MultiplexMappingEntry[] strokeEntries = new MultiplexMappingEntry[1];
110         strokeEntries[0] = new MultiplexMappingEntry("basic", BasicStroke  .class.getName());
111         addMultiplexMapping(Stroke  .class, "type", strokeEntries);
112         addManualMapping(BasicStroke  .class, BasicStrokeWriteHandler.class);
113 
114         // set up handling for Rectangle2D objects
115         final MultiplexMappingEntry[] rectangle2DEntries = new MultiplexMappingEntry[2];
116         rectangle2DEntries[0] = new MultiplexMappingEntry(
117             "float", Rectangle2D.Float  .class.getName()
118         );
119         rectangle2DEntries[1] = new MultiplexMappingEntry(
120             "double", Rectangle2D.Double  .class.getName()
121         );
122         addMultiplexMapping(Rectangle2D  .class, "type", rectangle2DEntries);
123         addManualMapping(Rectangle2D.Float  .class, Rectangle2DWriteHandler.class);
124         addManualMapping(Rectangle2D.Double  .class, Rectangle2DWriteHandler.class);
125 
126         // set up handling for List objects
127         final MultiplexMappingEntry[] listEntries = new MultiplexMappingEntry[4];
128         listEntries[0] = new MultiplexMappingEntry("array-list", ArrayList  .class.getName());
129         listEntries[1] = new MultiplexMappingEntry("linked-list", LinkedList  .class.getName());
130         listEntries[2] = new MultiplexMappingEntry("vector", Vector  .class.getName());
131         listEntries[3] = new MultiplexMappingEntry("stack", Stack  .class.getName());
132         addMultiplexMapping(List  .class, "type", listEntries);
133         addManualMapping(LinkedList  .class, ListWriteHandler.class);
134         addManualMapping(Vector  .class, ListWriteHandler.class);
135         addManualMapping(ArrayList  .class, ListWriteHandler.class);
136         addManualMapping(Stack  .class, ListWriteHandler.class);
137 
138         // handle all other direct mapping types
139         addManualMapping(RenderingHints  .class, RenderingHintsWriteHandler.class);
140         addManualMapping(Insets  .class, InsetsWriteHandler.class);
141         addManualMapping(Font  .class, FontWriteHandler.class);
142     }
143 
144     /**
145      * Returns the object factory.
146      * 
147      * @return the object factory.
148      */
149     protected abstract ObjectFactory getFactoryLoader();
150 
151     /**
152      * Adds a new manual mapping to this handler.
153      *
154      * This method provides support for the manual mapping. The manual mapping
155      * will become active before the multiplexers were queried. This facility
156      * could be used to override the model definition.
157      *
158      * @param classToWrite the class, which should be handled
159      * @param handler the write handler implementation for that class.
160      */
161     protected void addManualMapping(final Class   classToWrite, final Class   handler) {
162         if (handler == null) {
163             throw new NullPointerException  ("handler must not be null.");
164         }
165         if (classToWrite == null) {
166             throw new NullPointerException  ("classToWrite must not be null.");
167         }
168         if (!XmlWriteHandler.class.isAssignableFrom(handler)) {
169             throw new IllegalArgumentException  ("The given handler is no XmlWriteHandler.");
170         }
171 
172         this.classToHandlerMapping.addManualMapping
173             (new ManualMappingDefinition(classToWrite, null, handler.getName()));
174     }
175 
176     /**
177      * Adds a multiplex mapping.
178      * 
179      * @param baseClass  the base class.
180      * @param typeAttr  the type attribute.
181      * @param mdef  the mapping entries.
182      */
183     protected void addMultiplexMapping(final Class   baseClass,
184                                        final String   typeAttr,
185                                        final MultiplexMappingEntry[] mdef) {
186         
187         this.classToHandlerMapping.addMultiplexMapping(
188             new MultiplexMappingDefinition(baseClass, typeAttr, mdef)
189         );
190         
191     }
192 
193     /**
194      * Tries to find the mapping for the given class. This will first check
195      * the manual mapping and then try to use the object factory to resolve
196      * the class parameter into a write handler.
197      *
198      * @param classToWrite the class for which to find a handler.
199      * @return the write handler, never null.
200      * @throws XMLWriterException if no handler could be found for the given class.
201      */
202     protected XmlWriteHandler getMapping(final Class   classToWrite) throws XMLWriterException {
203 
204         if (classToWrite == null) {
205             throw new NullPointerException  ("ClassToWrite is null.");
206         }
207 
208         // search direct matches, first the direct definitions ...
209         ManualMappingDefinition manualMapping =
210             this.classToHandlerMapping.getManualMappingDefinition(classToWrite);
211         if (manualMapping == null) {
212             // search the manual mappings from the xml file.
213             manualMapping = getFactoryLoader().getManualMappingDefinition(classToWrite);
214         }
215         if (manualMapping != null) {
216             return loadHandlerClass(manualMapping.getWriteHandler());
217         }
218 
219 
220         // multiplexer definitions can be safely ignored here, as they are used to
221         // map parent classes to more specific child classes. In this case, we already
222         // know the child class and can look up the handler directly.
223 
224         // of course we have to check for multiplexers later, so that we can apply
225         // the mutiplex-attributes.
226 
227         // and finally try the generic handler matches ...
228         if (this.classToHandlerMapping.isGenericHandler(classToWrite)) {
229             return new GenericWriteHandler(
230                 this.classToHandlerMapping.getFactoryForClass(classToWrite)
231             );
232         }
233         if (getFactoryLoader().isGenericHandler(classToWrite)) {
234             return new GenericWriteHandler(getFactoryLoader().getFactoryForClass(classToWrite));
235         }
236 
237         throw new XMLWriterException("Unable to handle " + classToWrite);
238     }
239 
240     /**
241      * Writes the given object with the specified tagname. This method will
242      * do nothing, if the given object is null.
243      *
244      * @param tagName  the tagname for the xml-element containing the object
245      * definition. The tagname must not be null.
246      * @param object  the object which should be written.
247      * @param baseClass  the base class.
248      * @param writer  the xml writer used to write the content, never null.
249      * 
250      * @throws IOException if an IOException occures.
251      * @throws XMLWriterException if an object model related error occures during
252      * the writing.
253      */
254     public void write(final String   tagName, final Object   object, final Class   baseClass, final XMLWriter writer)
255         throws IOException  , XMLWriterException {
256         if (object == null) {
257             return;
258         }
259         if (tagName == null) {
260             throw new NullPointerException  ("RootXmlWriteHandler.write(..) : tagName is null");
261         }
262         if (writer == null) {
263             throw new NullPointerException  ("RootXmlWriteHandler.write(..) : writer is null");
264         }
265         if (!baseClass.isInstance(object)) {
266             throw new ClassCastException  ("Object is no instance of " + baseClass);
267         }
268         final Class   classToWrite = object.getClass();
269         final XmlWriteHandler handler = getMapping(classToWrite);
270         handler.setRootHandler(this);
271 
272         String   attributeName = null;
273         String   attributeValue = null;
274 
275         // find multiplexer for this class...
276         MultiplexMappingDefinition mplex =
277             getFactoryLoader().getMultiplexDefinition(baseClass);
278         if (mplex == null) {
279             mplex = this.classToHandlerMapping.getMultiplexDefinition(baseClass);
280         }
281         if (mplex != null) {
282             final MultiplexMappingEntry entry =
283                 mplex.getEntryForClass(classToWrite.getName());
284             if (entry != null) {
285                 attributeName = mplex.getAttributeName();
286                 attributeValue = entry.getAttributeValue();
287             }
288             else {
289                 throw new XMLWriterException(
290                     "Unable to find child mapping for multiplexer " 
291                     + baseClass + " to child " + classToWrite
292                 );
293             }
294         }
295 
296         handler.write(tagName, object, writer, attributeName, attributeValue);
297         writer.allowLineBreak();
298     }
299 
300     /**
301      * Loads the given class, and ignores all exceptions which may occur
302      * during the loading. If the class was invalid, null is returned instead.
303      *
304      * @param className the name of the class to be loaded.
305      * @return the class or null.
306      * 
307      * @throws XMLWriterException if there is a writer exception.
308      */
309     protected XmlWriteHandler loadHandlerClass(final String   className)
310         throws XMLWriterException {
311         if (className == null) {
312             throw new XMLWriterException("LoadHanderClass: Class name not defined");
313         }
314         try {
315             final Class   c = ObjectUtilities.getClassLoader(getClass()).loadClass(className);
316             return (XmlWriteHandler) c.newInstance();
317         }
318         catch (Exception   e) {
319             // ignore buggy classes for now ..
320             throw new XMLWriterException("LoadHanderClass: Unable to instantiate " + className, e);
321         }
322     }
323     
324 }
325
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