RendererFactory


1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  /* $Id: RendererFactory.java 426576 2006-07-28 15:44:37Z jeremias $ */
19   
20  package org.apache.fop.render;
21  
22  import java.io.OutputStream  ;
23  import java.util.Collections  ;
24  import java.util.Iterator  ;
25  import java.util.List  ;
26  import java.util.Map  ;
27  
28  import org.apache.avalon.framework.configuration.Configuration;
29  import org.apache.avalon.framework.configuration.ConfigurationException;
30  import org.apache.avalon.framework.container.ContainerUtil;
31  import org.apache.commons.logging.Log;
32  import org.apache.commons.logging.LogFactory;
33  
34  import org.apache.xmlgraphics.util.Service;
35  
36  import org.apache.fop.apps.FOPException;
37  import org.apache.fop.apps.FOUserAgent;
38  import org.apache.fop.area.AreaTreeHandler;
39  import org.apache.fop.fo.FOEventHandler;
40  
41  /**
42   * Factory for FOEventHandlers and Renderers.
43   */
44  public class RendererFactory {
45      
46      /** the logger */
47      private static Log log = LogFactory.getLog(RendererFactory.class);
48  
49      private Map   rendererMakerMapping = new java.util.HashMap  ();
50      private Map   eventHandlerMakerMapping = new java.util.HashMap  ();
51      
52      
53      /**
54       * Main constructor.
55       */
56      public RendererFactory() {
57          discoverRenderers();
58          discoverFOEventHandlers();
59      }
60      
61      /**
62       * Add a new RendererMaker. If another maker has already been registered for a
63       * particular MIME type, this call overwrites the existing one.
64       * @param maker the RendererMaker
65       */
66      public void addRendererMaker(AbstractRendererMaker maker) {
67          String  [] mimes = maker.getSupportedMimeTypes();
68          for (int i = 0; i < mimes.length; i++) {
69              //This overrides any renderer previously set for a MIME type
70              if (rendererMakerMapping.get(mimes[i]) != null) {
71                  log.trace("Overriding renderer for " + mimes[i] 
72                          + " with " + maker.getClass().getName());
73              }
74              rendererMakerMapping.put(mimes[i], maker);
75          }
76      }
77      
78      /**
79       * Add a new FOEventHandlerMaker. If another maker has already been registered for a
80       * particular MIME type, this call overwrites the existing one.
81       * @param maker the FOEventHandlerMaker
82       */
83      public void addFOEventHandlerMaker(AbstractFOEventHandlerMaker maker) {
84          String  [] mimes = maker.getSupportedMimeTypes();
85          for (int i = 0; i < mimes.length; i++) {
86              //This overrides any event handler previously set for a MIME type
87              if (eventHandlerMakerMapping.get(mimes[i]) != null) {
88                  log.trace("Overriding FOEventHandler for " + mimes[i] 
89                          + " with " + maker.getClass().getName());
90              }
91              eventHandlerMakerMapping.put(mimes[i], maker);
92          }
93      }
94      
95      /**
96       * Add a new RendererMaker. If another maker has already been registered for a
97       * particular MIME type, this call overwrites the existing one.
98       * @param className the fully qualified class name of the RendererMaker
99       */
100     public void addRendererMaker(String   className) {
101         try {
102             AbstractRendererMaker makerInstance
103                 = (AbstractRendererMaker)Class.forName(className).newInstance();
104             addRendererMaker(makerInstance);
105         } catch (ClassNotFoundException   e) {
106             throw new IllegalArgumentException  ("Could not find "
107                                                + className);
108         } catch (InstantiationException   e) {
109             throw new IllegalArgumentException  ("Could not instantiate "
110                                                + className);
111         } catch (IllegalAccessException   e) {
112             throw new IllegalArgumentException  ("Could not access "
113                                                + className);
114         } catch (ClassCastException   e) {
115             throw new IllegalArgumentException  (className
116                                                + " is not an "
117                                                + AbstractRendererMaker.class.getName());
118         }
119     }
120     
121     /**
122      * Add a new FOEventHandlerMaker. If another maker has already been registered for a
123      * particular MIME type, this call overwrites the existing one.
124      * @param className the fully qualified class name of the FOEventHandlerMaker
125      */
126     public void addFOEventHandlerMaker(String   className) {
127         try {
128             AbstractFOEventHandlerMaker makerInstance
129                 = (AbstractFOEventHandlerMaker)Class.forName(className).newInstance();
130             addFOEventHandlerMaker(makerInstance);
131         } catch (ClassNotFoundException   e) {
132             throw new IllegalArgumentException  ("Could not find "
133                                                + className);
134         } catch (InstantiationException   e) {
135             throw new IllegalArgumentException  ("Could not instantiate "
136                                                + className);
137         } catch (IllegalAccessException   e) {
138             throw new IllegalArgumentException  ("Could not access "
139                                                + className);
140         } catch (ClassCastException   e) {
141             throw new IllegalArgumentException  (className
142                                                + " is not an "
143                                                + AbstractFOEventHandlerMaker.class.getName());
144         }
145     }
146     
147     /**
148      * Returns a RendererMaker which handles the given MIME type.
149      * @param mime the requested output format
150      * @return the requested RendererMaker or null if none is available
151      */
152     public AbstractRendererMaker getRendererMaker(String   mime) {
153         AbstractRendererMaker maker
154             = (AbstractRendererMaker)rendererMakerMapping.get(mime);
155         return maker;
156     }
157     
158     /**
159      * Returns a FOEventHandlerMaker which handles the given MIME type.
160      * @param mime the requested output format
161      * @return the requested FOEventHandlerMaker or null if none is available
162      */
163     public AbstractFOEventHandlerMaker getFOEventHandlerMaker(String   mime) {
164         AbstractFOEventHandlerMaker maker
165             = (AbstractFOEventHandlerMaker)eventHandlerMakerMapping.get(mime);
166         return maker;
167     }
168     
169     /**
170      * Creates a Renderer object based on render-type desired
171      * @param userAgent the user agent for access to configuration
172      * @param outputFormat the MIME type of the output format to use (ex. "application/pdf").
173      * @return the new Renderer instance
174      * @throws FOPException if the renderer cannot be properly constructed
175      */
176     public Renderer createRenderer(FOUserAgent userAgent, String   outputFormat) 
177                     throws FOPException {
178         if (userAgent.getRendererOverride() != null) {
179             return userAgent.getRendererOverride();
180         } else {
181             AbstractRendererMaker maker = getRendererMaker(outputFormat);
182             if (maker == null) {
183                 throw new UnsupportedOperationException  (
184                         "No renderer for the requested format available: " + outputFormat);
185             }
186             Renderer rend = maker.makeRenderer(userAgent);
187             rend.setUserAgent(userAgent);
188             String   mimeType = rend.getMimeType(); //Always use main MIME type for this
189             Configuration userRendererConfig = null;
190             if (mimeType != null) {
191                 userRendererConfig
192                     = userAgent.getUserRendererConfig(mimeType);
193             }
194             if (userRendererConfig != null) {
195                 try {
196                     ContainerUtil.configure(rend, userRendererConfig);
197                 } catch (ConfigurationException e) {
198                     throw new FOPException(e);
199                 }
200             }
201             return rend;
202         }
203     }
204     
205     
206     /**
207      * Creates FOEventHandler instances based on the desired output.
208      * @param userAgent the user agent for access to configuration
209      * @param outputFormat the MIME type of the output format to use (ex. "application/pdf").
210      * @param out the OutputStream where the output is written to (if applicable)
211      * @return the newly constructed FOEventHandler
212      * @throws FOPException if the FOEventHandler cannot be properly constructed
213      */
214     public FOEventHandler createFOEventHandler(FOUserAgent userAgent, 
215                 String   outputFormat, OutputStream   out) throws FOPException {
216 
217         if (userAgent.getFOEventHandlerOverride() != null) {
218             return userAgent.getFOEventHandlerOverride();
219         } else {
220             AbstractFOEventHandlerMaker maker = getFOEventHandlerMaker(outputFormat);
221             if (maker == null) {
222                 AbstractRendererMaker rendMaker = getRendererMaker(outputFormat);
223                 if (rendMaker == null && userAgent.getRendererOverride() == null) {
224                     throw new UnsupportedOperationException  (
225                             "Don't know how to handle \"" + outputFormat + "\" as an output format."
226                             + " Neither an FOEventHandler, nor a Renderer could be found"
227                             + " for this output format.");
228                 } else {
229                     if (out == null 
230                             && userAgent.getRendererOverride() == null 
231                             && rendMaker.needsOutputStream()) {
232                         throw new FOPException(
233                             "OutputStream has not been set");
234                     }
235                     //Found a Renderer so we need to construct an AreaTreeHandler.
236                     return new AreaTreeHandler(userAgent, outputFormat, out);
237                 }
238             } else {
239                 return maker.makeFOEventHandler(userAgent, out);
240             }
241         }
242     }
243     
244     /**
245      * @return an array of all supported MIME types
246      */
247     public String  [] listSupportedMimeTypes() {
248         List   lst = new java.util.ArrayList  ();
249         Iterator   iter = this.rendererMakerMapping.keySet().iterator();
250         while (iter.hasNext()) {
251             lst.add(((String  )iter.next()));
252         }
253         iter = this.eventHandlerMakerMapping.keySet().iterator();
254         while (iter.hasNext()) {
255             lst.add(((String  )iter.next()));
256         }
257         Collections.sort(lst);
258         return (String  [])lst.toArray(new String  [lst.size()]);
259     }
260     
261     /**
262      * Discovers Renderer implementations through the classpath and dynamically
263      * registers them.
264      */
265     private void discoverRenderers() {
266         // add mappings from available services
267         Iterator   providers
268             = Service.providers(Renderer.class);
269         if (providers != null) {
270             while (providers.hasNext()) {
271                 AbstractRendererMaker maker = (AbstractRendererMaker)providers.next();
272                 try {
273                     if (log.isDebugEnabled()) {
274                         log.debug("Dynamically adding maker for Renderer: " 
275                                 + maker.getClass().getName());
276                     }
277                     addRendererMaker(maker);
278                 } catch (IllegalArgumentException   e) {
279                     log.error("Error while adding maker for Renderer", e);
280                 }
281 
282             }
283         }
284     }
285     
286     /**
287      * Discovers FOEventHandler implementations through the classpath and dynamically
288      * registers them.
289      */
290     private void discoverFOEventHandlers() {
291         // add mappings from available services
292         Iterator   providers
293             = Service.providers(FOEventHandler.class);
294         if (providers != null) {
295             while (providers.hasNext()) {
296                 AbstractFOEventHandlerMaker maker = (AbstractFOEventHandlerMaker)providers.next();
297                 try {
298                     if (log.isDebugEnabled()) {
299                         log.debug("Dynamically adding maker for FOEventHandler: " 
300                                 + maker.getClass().getName());
301                     }
302                     addFOEventHandlerMaker(maker);
303                 } catch (IllegalArgumentException   e) {
304                     log.error("Error while adding maker for FOEventHandler", e);
305                 }
306 
307             }
308         }
309     }
310     
311 }
312
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