Current File : //proc/thread-self/root/home/waritko/yacy/source/net/yacy/cora/document/feed/RSSFeed.java
/**
* RSSFeed
* Copyright 2007 by Michael Peter Christen
* First released 16.7.2007 at http://yacy.net
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program in the file lgpl21.txt
* If not, see <http://www.gnu.org/licenses/>.
*/
package net.yacy.cora.document.feed;
import java.net.MalformedURLException;
import java.util.Collections;
import java.util.ConcurrentModificationException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import net.yacy.cora.document.id.MultiProtocolURL;
public class RSSFeed implements Iterable<RSSMessage> {
public static final int DEFAULT_MAXSIZE = 10000;
// class variables
/** Single required element see http://www.rssboard.org/rss-profile#element-channel */
private RSSMessage channel = null;
/** A guid:Item map */
private final Map<String, RSSMessage> messages;
private final int maxsize;
/** Set to true when maxsize messages limit has been exceeded and exceeding messages have been discarded */
private boolean maxSizeExceeded;
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
sb.append("<rss version=\"2.0\"\n");
sb.append(" xmlns:opensearch=\"http://a9.com/-/spec/opensearch/1.1/\"\n");
sb.append(" xmlns:atom=\"http://www.w3.org/2005/Atom\"\n");
sb.append(">\n");
sb.append("<channel>\n");
if (this.channel != null) sb.append(this.channel.toString(false));
sb.append("<opensearch:startIndex>0</opensearch:startIndex>\n");
sb.append("<opensearch:itemsPerPage>" + this.size() + "</opensearch:itemsPerPage>\n");
sb.append("<opensearch:totalResults>" + this.size() + "</opensearch:totalResults>\n");
for (RSSMessage item: messages.values()) {
sb.append(item.toString());
}
sb.append("</channel>\n");
sb.append("</rss>\n");
return sb.toString();
}
public RSSFeed(final int maxsize) {
this.messages = Collections.synchronizedMap(new LinkedHashMap<String, RSSMessage>());
this.channel = null;
this.maxsize = maxsize;
this.maxSizeExceeded = false;
}
/**
* make a RSS feed using a set of urls
* the source string is assigned to all messages as author to mark the messages' origin
* @param links
* @param source
*/
public RSSFeed(Set<MultiProtocolURL> links, String source) {
this(Integer.MAX_VALUE);
String u;
RSSMessage message;
for (MultiProtocolURL uri: links) {
u = uri.toNormalform(true);
message = new RSSMessage(u, "", u);
message.setAuthor(source);
this.addMessage(message);
}
}
public void setChannel(final RSSMessage channelItem) {
this.channel = channelItem;
}
/**
* Return Channel element
* (This element is required and must contain three child elements: description, link and title)
* see http://www.rssboard.org/rss-profile#element-channel
* @return RSSMessage with channel elements or empty RSSMessage
*/
public RSSMessage getChannel() {
// This element is required and must contain three child elements: description, link and title.
if (this.channel==null) this.channel = new RSSMessage();
return this.channel;
}
public Set<MultiProtocolURL> getLinks() {
Set<MultiProtocolURL> links = new HashSet<MultiProtocolURL>();
for (RSSMessage message: this.messages.values()) {
try {links.add(new MultiProtocolURL(message.getLink()));} catch (final MalformedURLException e) {}
}
return links;
}
public void addMessage(final RSSMessage item) {
final String guid = item.getGuid();
this.messages.put(guid, item);
// in case that the feed is full (size > maxsize) flush the oldest element
while (this.messages.size() > this.maxsize) {
this.maxSizeExceeded = true;
pollMessage();
}
}
public RSSMessage getMessage(final String guid) {
// retrieve item by guid
return this.messages.get(guid);
}
public boolean isEmpty() {
return this.messages.isEmpty();
}
public int size() {
return this.messages.size();
}
/**
* @return true when maxsize messages limit has been exceeded and exceeding messages have been discarded
*/
public boolean isMaxSizeExceeded() {
return this.maxSizeExceeded;
}
@Override
public Iterator<RSSMessage> iterator() {
return new messageIterator();
}
public RSSMessage pollMessage() {
// retrieve and delete item
synchronized (this.messages) {
if (this.messages.isEmpty()) return null;
final String nextGUID = this.messages.keySet().size() == 0 ? null : this.messages.keySet().iterator().next();
if (nextGUID == null) return null;
return this.messages.remove(nextGUID);
}
}
public class messageIterator implements Iterator<RSSMessage>{
Iterator<String> GUIDiterator;
String lastGUID;
int t;
public messageIterator() {
this.t = RSSFeed.this.messages.size(); // termination counter
this.GUIDiterator = RSSFeed.this.messages.keySet().iterator();
this.lastGUID = null;
}
@Override
public boolean hasNext() {
if (this.t <= 0) return false; // ensure termination
return this.GUIDiterator.hasNext();
}
@Override
public RSSMessage next() {
this.t--; // ensure termination
try {
this.lastGUID = this.GUIDiterator.next();
} catch (final ConcurrentModificationException e) {
//ConcurrentLog.logException(e);
this.lastGUID = null;
}
if (this.lastGUID == null) return null;
return RSSFeed.this.messages.get(this.lastGUID);
}
@Override
public void remove() {
if (this.lastGUID == null) return;
this.GUIDiterator.remove();
RSSFeed.this.messages.remove(this.lastGUID);
}
}
}
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