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Java > Open Source Codes > org > blojsom > plugin > xpath > XPathPlugin


1 /**
2  * Copyright (c) 2003-2006, David A. Czarnecki
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  * Redistributions of source code must retain the above copyright notice, this list of conditions and the
9  * following disclaimer.
10  * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
11  * following disclaimer in the documentation and/or other materials provided with the distribution.
12  * Neither the name of "David A. Czarnecki" and "blojsom" nor the names of its contributors may be used to
13  * endorse or promote products derived from this software without specific prior written permission.
14  * Products derived from this software may not be called "blojsom", nor may "blojsom" appear in their name,
15  * without prior written permission of David A. Czarnecki.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
18  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
19  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
20  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
21  * EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
29  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 package org.blojsom.plugin.xpath;
32
33 import org.apache.commons.jxpath.JXPathContext;
34 import org.apache.commons.logging.Log;
35 import org.apache.commons.logging.LogFactory;
36 import org.blojsom.blog.Blog;
37 import org.blojsom.blog.Entry;
38 import org.blojsom.plugin.Plugin;
39 import org.blojsom.plugin.PluginException;
40
41 import javax.servlet.http.HttpServletRequest JavaDoc;
42 import javax.servlet.http.HttpServletResponse JavaDoc;
43 import java.util.ArrayList JavaDoc;
44 import java.util.Iterator JavaDoc;
45 import java.util.List JavaDoc;
46 import java.util.Map JavaDoc;
47
48 /**
49  * XPathPlugin
50  *
51  * @author David Czarnecki
52  * @author Mark Lussier
53  * @version $Id: XPathPlugin.java,v 1.1 2006/03/23 07:15:47 czarneckid Exp $
54  * @since blojsom 3.0
55  */
56 public class XPathPlugin implements Plugin {
57
58     private static final String JavaDoc XPATH_PARAM = "xpath";
59
60     private Log _logger = LogFactory.getLog(XPathPlugin.class);
61
62     /**
63      * Initialize this plugin. This method only called when the plugin is instantiated.
64      *
65      * @throws org.blojsom.plugin.PluginException
66      * If there is an error initializing the plugin
67      */
68     public void init() throws PluginException {
69         JXPathContext.newContext(Entry.class);
70     }
71
72     /**
73      * Process the blog entries
74      *
75      * @param httpServletRequest Request
76      * @param httpServletResponse Response
77      * @param blog {@link Blog} instance
78      * @param context Context
79      * @param entries Blog entries retrieved for the particular request
80      * @return Modified set of blog entries
81      * @throws PluginException If there is an error processing the blog entries
82      */
83     public Entry[] process(HttpServletRequest JavaDoc httpServletRequest, HttpServletResponse JavaDoc httpServletResponse, Blog blog, Map JavaDoc context, Entry[] entries) throws PluginException {
84         Entry[] results;
85         String JavaDoc xpath = httpServletRequest.getParameter(XPATH_PARAM);
86
87         if (xpath != null && !"".equals(xpath)) {
88             xpath = xpath.trim();
89
90             if (_logger.isDebugEnabled()) {
91                 _logger.debug("Attempting xpath query with: " + xpath);
92             }
93
94             EntryWrapper entryWrapper = new EntryWrapper(entries);
95             List JavaDoc foundEntries = new ArrayList JavaDoc();
96             JXPathContext xpathcontext = JXPathContext.newContext(entryWrapper);
97
98             try {
99                 Iterator JavaDoc entryIterator = xpathcontext.iterate(xpath);
100
101                 while (entryIterator.hasNext()) {
102                     Object JavaDoc object = entryIterator.next();
103                     Entry entry = (Entry) object;
104                     foundEntries.add(entry);
105                 }
106             } catch (Exception JavaDoc e) {
107                 if (_logger.isErrorEnabled()) {
108                     _logger.error(e);
109                 }
110             }
111
112             if (foundEntries.size() == 0) {
113                 results = new Entry[0];
114             } else {
115                 results = new Entry[foundEntries.size()];
116                 for (int x = 0; x < foundEntries.size(); x++) {
117                     results[x] = (Entry) foundEntries.get(x);
118                 }
119             }
120         } else {
121             results = entries;
122         }
123
124         return results;
125     }
126
127     /**
128      * Perform any cleanup for the plugin. Called after {@link #process}.
129      *
130      * @throws PluginException If there is an error performing cleanup for this plugin
131      */
132     public void cleanup() throws PluginException {
133     }
134
135     /**
136      * Called when BlojsomServlet is taken out of service
137      *
138      * @throws PluginException If there is an error in finalizing this plugin
139      */
140     public void destroy() throws PluginException {
141     }
142 }
143
144
145
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