1 /**
2 * This file Copyright (c) 2008-2016 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 static info.magnolia.module.rssaggregator.RSSAggregator.*;
37 import static java.lang.String.format;
38
39 import java.util.List;
40
41 import org.slf4j.Logger;
42 import org.slf4j.LoggerFactory;
43
44 import com.rometools.rome.feed.synd.SyndEntry;
45 import com.rometools.rome.feed.synd.SyndFeed;
46 import com.rometools.rome.feed.synd.SyndFeedImpl;
47 import com.rometools.rome.io.FeedException;
48 import com.rometools.rome.io.SyndFeedOutput;
49
50 /**
51 * Convenience base class providing plumbing required for generating a {@link Feed} from a {@link SyndFeed}.
52 * The generated feed will by default be of type
53 * {@link info.magnolia.module.rssaggregator.RSSAggregator#DEFAULT_FEEDTYPE}. Subclasses need implement the template
54 * methods {@link #loadFeedEntries()} and {@link #setFeedInfo(SyndFeed)} to have a Feed generated.
55 *
56 * @see FeedGenerator
57 * @see SyndFeed
58 * @see Feed
59 */
60 public abstract class AbstractSyndFeedGenerator implements FeedGenerator {
61
62 private static final Logger log = LoggerFactory.getLogger(AbstractSyndFeedGenerator.class);
63
64 public static final String PROPERTY_NAME_TITLE = "title";
65 public static final String PROPERTY_NAME_DESCRIPTION = "description";
66 public static final String PROPERTY_NAME_AUTHOR = "author";
67 public static final String PROPERTY_NAME_PUB_DATE = "pubDate";
68 public static final String PROPERTY_NAME_ABSTRACT = "abstract";
69 public static final String PROPERTY_NAME_CATEGORIES = "categories";
70
71 /**
72 * Generate a SyndFeed.
73 *
74 * @return the generated SyndFeed
75 * @throws FeedGenerationException when an exception occurs while generating the aggregate feed
76 */
77 @Override
78 public Feed generate() throws FeedGenerationException {
79 try {
80 SyndFeed syndFeed = newSyndFeed();
81 syndFeed.setFeedType(DEFAULT_FEEDTYPE);
82 syndFeed.setEntries(loadFeedEntries());
83 setFeedInfo(syndFeed);
84
85 String xml = syndFeedToXml(syndFeed);
86 return new Feed(xml, DEFAULT_CONTENT_TYPE, DEFAULT_ENCODING);
87 } catch (Exception e) {
88 String message = format("Failed to generate Feed using generator '%s'", getClass().getName());
89 log.error(message, e);
90 throw new FeedGenerationException(message, e);
91 }
92 }
93
94 protected String syndFeedToXml(SyndFeed feed) throws FeedException {
95 SyndFeedOutput feedOutput = new SyndFeedOutput();
96 return feedOutput.outputString(feed);
97 }
98
99 /**
100 * Construct a new SyndFeed instance.
101 *
102 * @return the new SyndFeed instance
103 */
104 protected SyndFeedImpl newSyndFeed() {
105 return new SyndFeedImpl();
106 }
107
108 /**
109 * Template method for subclasses to implement in order to provide the feed entries to include in the Feed to
110 * generate.
111 *
112 * @return the feed entries to include in the Feed to generate
113 */
114 public abstract List<SyndEntry> loadFeedEntries();
115
116 /**
117 * Template method for subclasses are to override in order to set appropriate Feed meta data. Typical use cases
118 * would be to set the {@link SyndFeed#setTitle(String) title} , {@link SyndFeed#setLink(String) link} and {@link
119 * SyndFeed#setDescription(String) description}. The given {@code feed} will never be null.
120 *
121 * @param feed the syndication feed that is generated to set the feed meta data for
122 */
123 public abstract void setFeedInfo(SyndFeed feed);
124
125 }