Java tutorial
/********************************************************************************** * $URL$ * $Id$ *********************************************************************************** * * Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009 The Sakai Foundation * * Licensed under the Educational Community License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.opensource.org/licenses/ECL-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * **********************************************************************************/ package org.sakaiproject.news.impl; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.text.DateFormat; import java.text.ParseException; import java.util.Date; import java.util.Iterator; import java.util.List; import java.util.Vector; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.sakaiproject.javax.Filter; import org.sakaiproject.news.api.NewsChannel; import org.sakaiproject.news.api.NewsConnectionException; import org.sakaiproject.news.api.NewsFormatException; import org.sakaiproject.news.api.NewsItem; import org.sakaiproject.news.api.NewsItemEnclosure; import org.sakaiproject.util.FormattedText; import org.sakaiproject.util.ResourceLoader; import org.sakaiproject.util.Validator; import org.sakaiproject.component.cover.ServerConfigurationService; import org.sakaiproject.tool.cover.SessionManager; import com.sun.syndication.feed.synd.SyndEnclosure; import com.sun.syndication.feed.synd.SyndEntry; import com.sun.syndication.feed.synd.SyndFeed; import com.sun.syndication.feed.synd.SyndImage; import com.sun.syndication.fetcher.FeedFetcher; import com.sun.syndication.fetcher.impl.HttpURLFeedFetcher; import com.sun.syndication.io.ParsingFeedException; /*********************************************************************************** * NewsChannel implementation **********************************************************************************/ public class BasicNewsChannel implements NewsChannel { protected String m_source = null; protected String m_userAgent = null; protected String m_link = null; protected String m_title = null; protected String m_description = null; protected String m_language = null; protected String m_copyright = null; protected String m_pubdate = null; protected String m_lastbuilddate = null; protected String m_imageLink = null; protected String m_imageTitle = null; protected String m_imageUrl = null; protected String m_imageHeight = "31"; protected String m_imageWidth = "88"; protected String m_imageDescription = null; protected List<NewsItem> m_items = null; /** Our log (commons). */ private static Log M_log = LogFactory.getLog(BasicNewsService.class); private ResourceLoader rl = new ResourceLoader("news-impl"); /** * Construct. * * @param source * The URL from which the feed can be obtained * @param userAgent * The user agent to make the request as. * @exception NewsConnectionException, * for errors making the connection. * @exception NewsFormatException, * for errors in the URL or errors parsing the feed. */ public BasicNewsChannel(String source, String userAgent) throws NewsConnectionException, NewsFormatException { if (m_items == null) { m_items = new Vector<NewsItem>(); } // get the file, parse it and cache it // throw NewsConnectionException if unable to get file // throw NewsFormatException if file is in wrong format m_userAgent = userAgent; initChannel(source); } // get the file, parse it and cache it // throw NewsConnectionException if unable to get file // throw NewsFormatException if file is in wrong format // updated to use ROME syndication api private void initChannel(String source) throws NewsConnectionException, NewsFormatException { SyndFeed feed = null; try { // if feedUrl is on this sakai server, add session parameter if (source.startsWith(ServerConfigurationService.getServerUrl())) { String sessionId = SessionManager.getCurrentSession().getId(); if (source.indexOf("?") != -1) source = source + "&session=" + sessionId; else source = source + "?session=" + sessionId; } URL feedUrl = new URL(source); FeedFetcher feedFetcher = new HttpURLFeedFetcher(); feedFetcher.setUserAgent(m_userAgent); feed = feedFetcher.retrieveFeed(feedUrl); } catch (MalformedURLException e) { if (M_log.isDebugEnabled()) M_log.debug("initChannel(" + source + ") bad url: " + e.getMessage()); throw new NewsFormatException("\"" + source + "\" " + rl.getString("is_not_a_valid_url")); } catch (IOException e) { if (M_log.isDebugEnabled()) M_log.debug("initChannel(" + source + ") constructor: couldn't connect: " + e.getMessage()); throw new NewsConnectionException(rl.getString("unable_to_obtain_news_feed") + " " + source); } catch (ParsingFeedException pfe) { M_log.info("initChannel(" + source + ") constructor: couldn't parse: " + source, pfe); throw new NewsConnectionException(rl.getString("unable_to_interpret") + " " + source); } catch (Exception e) { M_log.info("initChannel(" + source + ") constructor: couldn't parse: " + e.getMessage()); throw new NewsConnectionException(rl.getString("unable_to_interpret") + " " + source); } m_title = FormattedText.processEscapedHtml(feed.getTitle()); m_source = source; m_description = FormattedText.processEscapedHtml(feed.getDescription()); m_description = Validator.stripAllNewlines(m_description); m_lastbuilddate = ""; m_pubdate = ""; Date pubdate = feed.getPublishedDate(); if (pubdate != null) { m_pubdate = FormattedText.processEscapedHtml(DateFormat.getDateInstance().format(pubdate)); m_lastbuilddate = m_pubdate; } m_pubdate = Validator.stripAllNewlines(m_pubdate); m_lastbuilddate = Validator.stripAllNewlines(m_lastbuilddate); m_copyright = FormattedText.processEscapedHtml(feed.getCopyright()); m_copyright = Validator.stripAllNewlines(m_copyright); m_language = FormattedText.processEscapedHtml(feed.getLanguage()); m_language = Validator.stripAllNewlines(m_language); m_link = FormattedText.processEscapedHtml(feed.getLink()); m_link = Validator.stripAllNewlines(m_link); SyndImage image = feed.getImage(); if (image != null) { m_imageLink = FormattedText.processEscapedHtml(image.getLink()); m_imageLink = Validator.stripAllNewlines(m_imageLink); m_imageTitle = FormattedText.processEscapedHtml(image.getTitle()); m_imageTitle = Validator.stripAllNewlines(m_imageTitle); m_imageUrl = FormattedText.processEscapedHtml(image.getUrl()); m_imageUrl = Validator.stripAllNewlines(m_imageUrl); m_imageHeight = ""; m_imageWidth = ""; m_imageDescription = FormattedText.processEscapedHtml(image.getDescription()); m_imageDescription = Validator.stripAllNewlines(m_imageDescription); } // others?? m_items = new Vector<NewsItem>(); List items = feed.getEntries(); for (int i = 0; i < items.size(); ++i) { SyndEntry entry = (SyndEntry) items.get(i); String iTitle = FormattedText.processEscapedHtml(entry.getTitle()); iTitle = Validator.stripAllNewlines(iTitle); String iDescription = null; try { if (entry.getDescription() != null) { iDescription = FormattedText.processEscapedHtml(entry.getDescription().getValue()); iDescription = Validator.stripAllNewlines(iDescription); } } catch (Exception e) { M_log.warn(e); } String iLink = FormattedText.processEscapedHtml(entry.getLink()); iLink = Validator.stripAllNewlines(iLink); String iPubDate = ""; Date entrydate = entry.getPublishedDate(); if (entrydate != null) { iPubDate = FormattedText.processEscapedHtml(DateFormat.getDateInstance().format(entrydate)); } List<NewsItemEnclosure> enclosures = new Vector<NewsItemEnclosure>(); List syndEnclosures = entry.getEnclosures(); for (int j = 0; j < syndEnclosures.size(); j++) { SyndEnclosure syndEnclosure = (SyndEnclosure) syndEnclosures.get(j); enclosures.add(new BasicNewsItemEnclosure(FormattedText.processEscapedHtml(syndEnclosure.getUrl()), syndEnclosure.getType(), syndEnclosure.getLength())); } iPubDate = Validator.stripAllNewlines(iPubDate); m_items.add(new BasicNewsItem(iTitle, iDescription, iLink, iPubDate, enclosures)); } } // initChannel /** * A . * * @return the NewsItem that has the specified id. */ public List getNewsitems() { List<NewsItem> rv = new Vector<NewsItem>(); rv.addAll(m_items); return rv; } // getNewsitems /** * A . * * @param filter * A filtering object to accept messages, or null if no filtering is desired. * @return a list of NewsItems objects (may be empty). */ public List getNewsitems(Filter filter) { List items = new Vector<NewsItem>(m_items); if (filter != null) { List<NewsItem> accepted = new Vector<NewsItem>(); Iterator it = items.iterator(); while (it.hasNext()) { NewsItem item = (NewsItem) it.next(); if (filter.accept(item)) { accepted.add(item); } } items = accepted; } return items; } public String getSource() { return m_source; } public String getLink() { return m_link; } public String getTitle() { return m_title; } public String getDescription() { return m_description; } public String getLanguage() { return m_language; } public String getCopyright() { return m_copyright; } public String getPubdate() { return m_pubdate; } public Date getPubdateInDateFormat() { if (m_pubdate != null) { try { return DateFormat.getInstance().parse(m_pubdate); } catch (ParseException e) { } } return new Date(); } public String getLastbuilddate() { return m_lastbuilddate; } public Date getLastbuilddateInDateFormat() { if (m_lastbuilddate != null) { try { return DateFormat.getInstance().parse(m_lastbuilddate); } catch (ParseException e) { } } return new Date(); } public String getImageUrl() { return m_imageUrl; } public String getImageTitle() { return m_imageTitle; } public String getImageLink() { return m_imageLink; } public String getImageWidth() { return m_imageWidth; } public String getImageHeight() { return m_imageHeight; } public String getImageDescription() { return m_imageDescription; } public void setNewsitems(List items) { m_items = new Vector(items); } public void addNewsitem(NewsItem item) { m_items.add(item); } public void setSource(String source) throws NewsConnectionException, NewsFormatException { m_source = source; initChannel(source); } public void setLink(String link) { m_link = link; } public void setTitle(String title) { m_title = title; } public void setDescription(String description) { m_description = description; } public void setLanguage(String language) { m_language = language; } public void setCopyright(String copyright) { m_copyright = copyright; } public void setPubdate(String pubdate) { m_pubdate = pubdate; } public void setLastbuilddate(String builddate) { m_lastbuilddate = builddate; } public void setImageUrl(String imageUrl) { m_imageUrl = imageUrl; } public void setImageTitle(String imageTitle) { m_imageTitle = imageTitle; } public void setImageLink(String imageLink) { m_imageLink = imageLink; } public void setImageWidth(String imageWidth) { m_imageWidth = imageWidth; } public void setImageHeight(String imageHeight) { m_imageHeight = imageHeight; } public void setImageDescription(String imageDescription) { m_imageDescription = imageDescription; } /** * Checks whether an update is available for the rss news feed. * * @return true if update is available, false otherwise */ public boolean isUpdateAvailable() { // %%%%%%%% return true; } /** * Checks the relative ordering of the String url's of two Channels. Same * response pattern as compareTo method for Strings--negative if "this" * object is greater than parameter, zero if the objects are equal, and * positive if "this" object is less than the parameter. The parameter * can be a String reference or a NewsChannel object (otherwise method * throws ClassCastException). * * @return A negative integer if "this" object is greater than parameter, * zero if the objects are equal, and a positive integer if "this" object * is less than the parameter */ public int compareTo(Object obj) throws ClassCastException { int rv = 0; if (m_source == null) { if (obj != null) { rv = -1; } } else if (obj == null) { rv = 1; } else if (obj instanceof String) { rv = m_source.compareTo((String) obj); } else { NewsChannel other = (NewsChannel) obj; rv = m_source.compareTo(other.getLink()); } return rv; } /** * Checks whether the parameter obj refers to the same channel as "this" channel. * The parameter can be a String URL or a NewsChannel object (otherwise method * throws ClassCastException). * * @return true if the channels are the same, false otherwise */ public boolean equals(Object obj) throws ClassCastException { return (compareTo(obj) == 0); } /** * Calculates a hash code for the channel object's URL. * * @return The hash-code for the String URL to the channel. */ public int hashCode() { String hval = ""; if (m_source != null) { hval = m_source; } return hval.hashCode(); } } // BasicNewsChannel