1 /**
2 * This file Copyright (c) 2008-2010 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module.rssaggregator.generator;
35
36 import com.sun.syndication.feed.synd.SyndEntry;
37 import com.sun.syndication.feed.synd.SyndFeed;
38 import com.sun.syndication.feed.synd.SyndFeedImpl;
39 import com.sun.syndication.io.FeedException;
40 import com.sun.syndication.io.SyndFeedOutput;
41 import org.slf4j.Logger;
42 import org.slf4j.LoggerFactory;
43
44 import static java.lang.String.*;
45 import java.util.List;
46
47 import static info.magnolia.module.rssaggregator.RSSAggregator.*;
48
49 /**
50 * Convenience base class providing plumbing required for generating a Feed from a {@link SyndFeed}. The generated feed
51 * will by default be of type "{@value #DEFAULT_FEEDTYPE}". Subclasses need implement the template methods {@link
52 * #loadFeedEntries()} and {@link #setFeedInfo(SyndFeed)} to have a Feed generated.
53 *
54 * @author Rob van der Linden Vooren
55 * @see FeedGenerator
56 * @see SyndFeed
57 * @see Feed
58 */
59 public abstract class AbstractSyndFeedGenerator implements FeedGenerator {
60
61 private static final Logger log = LoggerFactory.getLogger(AbstractSyndFeedGenerator.class);
62
63 /**
64 * Generate a SyndFeed.
65 *
66 * @return the generated SyndFeed
67 * @throws FeedGenerationException when an exception occurs while generating the aggregate feed
68 */
69 public Feed generate() throws FeedGenerationException {
70 try {
71 SyndFeed syndFeed = newSyndFeed();
72 syndFeed.setFeedType(DEFAULT_FEEDTYPE);
73 syndFeed.setEntries(loadFeedEntries());
74 setFeedInfo(syndFeed);
75
76 String xml = syndFeedToXml(syndFeed);
77 return new Feed(xml, DEFAULT_CONTENT_TYPE, DEFAULT_ENCODING);
78 } catch (Exception e) {
79 String message = format("Failed to generate Feed using generator '%s'", getClass().getName());
80 log.error(message, e);
81 throw new FeedGenerationException(message, e);
82 }
83 }
84
85 protected String syndFeedToXml(SyndFeed feed) throws FeedException {
86 SyndFeedOutput feedOutput = new SyndFeedOutput();
87 return feedOutput.outputString(feed);
88 }
89
90 /**
91 * Construct a new SyndFeed instance.
92 *
93 * @return the new SyndFeed instance
94 */
95 protected SyndFeedImpl newSyndFeed() {
96 return new SyndFeedImpl();
97 }
98
99 /**
100 * Template method for subclasses to implement in order to provide the feed entries to include in the Feed to
101 * generate.
102 *
103 * @return the feed entries to include in the Feed to generate
104 */
105 public abstract List<SyndEntry> loadFeedEntries();
106
107 /**
108 * Template method for subclasses are to override in order to set appropriate Feed meta data. Typical use cases
109 * would be to set the {@link SyndFeed#setTitle(String) title} , {@link SyndFeed#setLink(String) link} and {@link
110 * SyndFeed#setDescription(String) description}. The given {@code feed} will never be null.
111 *
112 * @param feed the syndication feed that is generated to set the feed meta data for
113 */
114 public abstract void setFeedInfo(SyndFeed feed);
115
116 }