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1   /*
2    * Copyright 2000-2001,2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.jetspeed.portal.portlets.viewprocessor;
17  
18  //standard java stuff
19  import java.io.Reader;
20  import java.io.StringReader;
21  import java.util.Enumeration;
22  import java.util.Hashtable;
23  import java.util.Iterator;
24  import java.io.IOException;
25  
26  //JAXP support
27  import javax.xml.parsers.DocumentBuilder;
28  import javax.xml.parsers.DocumentBuilderFactory;
29  
30  // Jetspeed api
31  import org.apache.jetspeed.cache.disk.JetspeedDiskCache;
32  import org.apache.jetspeed.capability.CapabilityMap;
33  import org.apache.jetspeed.capability.CapabilityMapFactory;
34  import org.apache.jetspeed.portal.Portlet;
35  import org.apache.jetspeed.portal.PortletException;
36  import org.apache.jetspeed.portal.portlets.GenericMVCContext;
37  import org.apache.jetspeed.services.logging.JetspeedLogFactoryService;
38  import org.apache.jetspeed.services.logging.JetspeedLogger;
39  import org.apache.jetspeed.services.rundata.JetspeedRunData;
40  import org.apache.jetspeed.util.JetspeedClearElement;
41  import org.apache.jetspeed.util.MimeType;
42  import org.apache.jetspeed.util.SimpleTransform;
43  import org.apache.jetspeed.xml.JetspeedXMLEntityResolver;
44  
45  // Element Construction Set
46  import org.apache.ecs.ConcreteElement;
47  
48  // Turbine api
49  import org.apache.turbine.util.RunData;
50  
51  // XML stuff
52  import org.w3c.dom.Document;
53  import org.w3c.dom.Node;
54  import org.w3c.dom.NodeList;
55  import org.xml.sax.InputSource;
56  import org.xml.sax.SAXException;
57  
58  /***
59   * Simple ViewProcessor which does a basic XSLT transform with the stylesheet parameter
60   * and the given URL.
61   * 
62   * @author tkuebler@cisco.com
63   * @version $Id: $
64   * @since 1.4b4
65   */
66  
67  public class XSLViewProcessor implements ViewProcessor
68  {
69  
70      /***
71       * Static initialization of the logger for this class
72       */    
73      private static final JetspeedLogger logger = JetspeedLogFactoryService.getLogger(XSLViewProcessor.class.getName());
74      
75      private static final String XMLDECL = "<?xml version=";
76      public static final String ERROR_NOT_VALID = "This does not appear to be an XML document";
77      public static final String INVALID_TYPE = "Unable to display for this browser";
78      protected Document document = null;
79      protected Hashtable stylesheets = null;
80      private Hashtable params = null;
81  
82      /***
83       * This method loads the init parameters and
84       * parse the document tied to this portlet
85       * 
86       * @param portlet
87       * @exception PortletException
88       */
89      public void init(Portlet portlet)
90      throws PortletException
91      {
92  
93          DocumentBuilder parser = null;
94          String url = null;
95  
96          // load stylesheets available
97          stylesheets = new Hashtable();
98          params = new Hashtable();
99  
100         Iterator i = portlet.getPortletConfig().getInitParameterNames();
101 
102         while (i.hasNext())
103         {
104 
105             String name = (String) i.next();
106             String base = MimeType.HTML.toString();
107 
108             if (name.startsWith("stylesheet"))
109             {
110 
111                 int idx = -1;
112 
113                 if ((idx = name.indexOf(".")) > -1)
114                 {
115                     base = name.substring(idx + 1, name.length());
116                 }
117 
118                 stylesheets.put(base, portlet.getPortletConfig().getInitParameter(name));
119             }
120             else
121             {
122                 params.put(name.toLowerCase(), portlet.getPortletConfig().getInitParameter(name));
123             }
124         }
125 
126         // read content, clean it, parse it and cache the DOM
127         try
128         {
129 
130             final DocumentBuilderFactory docfactory = DocumentBuilderFactory.newInstance();
131 
132             //Have it non-validating
133             docfactory.setValidating(false);
134             parser = docfactory.newDocumentBuilder();
135             parser.setEntityResolver(new JetspeedXMLEntityResolver());
136             url = portlet.getPortletConfig().getURL();
137 
138             String content = JetspeedDiskCache.getInstance().getEntry(url).getData();
139             CapabilityMap xmap = CapabilityMapFactory.getCapabilityMap(CapabilityMapFactory.AGENT_XML);
140 
141             // no cache yet // portlet.setContent( new JetspeedClearElement(content), xmap );
142             InputSource isrc = new InputSource(this.cleanse(content));
143             isrc.setSystemId(url);
144             isrc.setEncoding("UTF-8");
145             this.document = parser.parse(isrc);
146         }
147         catch (Throwable t)
148         {
149 
150             String message = "XSLViewProcessor:  Couldn't parse out XML document -> " + url;
151             logger.error(message, t);
152             throw new PortletException(t.getMessage());
153         }
154 
155     }
156 
157     /***
158      * This methods outputs the content of the portlet for a given
159      * request.
160      * 
161      * @param context
162      * @return the content to be displayed to the user-agent
163      */
164     public Object processView(GenericMVCContext context)
165     {
166 
167         try
168         {
169             init((Portlet) context.get("portlet"));
170         }
171         catch (PortletException pe)
172         {
173             logger.error("XSLViewProcessor - error: " + pe.getMessage(), pe);
174         }
175 
176         RunData data = (RunData) context.get("data");
177         CapabilityMap map = ((JetspeedRunData) data).getCapability();
178         String type = map.getPreferredType().toString();
179         ConcreteElement content = new JetspeedClearElement(INVALID_TYPE);
180         String stylesheet = (String) stylesheets.get(type);
181 
182         if (stylesheet != null)
183         {
184 
185             try
186             {
187                 content = new JetspeedClearElement(SimpleTransform.transform(this.document, stylesheet, this.params));
188 
189                 // no caching yet // setContent( content, map );
190             }
191             catch (SAXException e)
192             {
193                 logger.error("SAXException", e);
194                 content = new JetspeedClearElement(e.getMessage());
195             }
196         }
197         else
198         {
199             content = new JetspeedClearElement("stylesheet not defined");
200         }
201 
202         return content;
203     }
204 
205     /***
206      * This portlet supports has many types as those
207      * it has stylesheets defined for in its parameters
208      * 
209      * @param mimeType the MIME type queried
210      * @return true if the portlet knows how to display
211      *         content for mimeType
212      * @see Portlet#supportsType
213      */
214     public boolean supportsType(MimeType mimeType)
215     {
216 
217         Enumeration en = stylesheets.keys();
218 
219         while (en.hasMoreElements())
220         {
221 
222             String type = (String) en.nextElement();
223 
224             if (type.equals(mimeType.toString()))
225             {
226 
227                 return true;
228             }
229         }
230 
231         return false;
232     }
233 
234     /***
235      * Utility method for traversing the document parsed
236      * DOM tree and retrieving a Node by tagname
237      * 
238      * @param start  the parent node for the search
239      * @param name   the tag name to be searched for
240      * @return the first child node of start whose tagname
241      *         is name
242      */
243     protected Node getNode(Node start, String name)
244     {
245 
246         NodeList list = start.getChildNodes();
247 
248         for (int i = 0; i < list.getLength(); ++i)
249         {
250 
251             Node node = list.item(i);
252 
253             if (node.getNodeName().equals(name))
254             {
255 
256                 return node;
257             }
258         }
259 
260         return null;
261     }
262 
263     /***
264      *  Given a URL to some content, clean the content to Xerces can handle it
265      *  better.  Right now this involves:
266      * <ul>
267      *     <li>
268      *         If the document doesn't begin with "&lt;?xml version=" truncate the
269      *         content until this is the first line
270      *     </li>
271      * 
272      * </ul>
273      * 
274      * @param content
275      * @return 
276      * @exception IOException
277      */
278     protected Reader cleanse(String content)
279     throws IOException
280     {
281 
282         String filtered = null;
283         int start = content.indexOf(XMLDECL);
284 
285         if (start <= 0)
286         {
287             filtered = content;
288         }
289         else
290         {
291             filtered = content.substring(start, content.length());
292         }
293 
294         return new StringReader(filtered);
295     }
296 }