corefeed.java

这是linux下ssl vpn的实现程序

/*
 *  SSL-Explorer
 *
 *  Copyright (C) 2003-2006 3SP LTD. All Rights Reserved
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2 of
 *  the License, or (at your option) any later version.
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
			
package com.sslexplorer.core;

import java.net.URL;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.XmlReader;

/**
 * Thread that wraps a {@link com.sun.syndication.io.SyndFeedInput} as is
 * responsible for downloading and maintaining the current status of the feed.
 * <p>
 * The feed may be in one of 4 states :-
 * <ul>
 * <li>Loading. The feed is currently being downloaded from the source site.</li>
 * <li>Loaded. The feed has successfuly been downloaded from the source site.</li>
 * <li>Empty. The feed has successfuly been downloaded but was empty.</li>
 * <li>Failed To Load. The feed failed to load.</li>
 * </ul>
 * 
 * @author Brett Smith <a href="mailto: [e-mail]">&lt;[e-mail]&gt;</a>
 * @version $Revision: 1.7 $
 */
public class CoreFeed extends Thread {

    final static Log log = LogFactory.getLog(CoreFeed.class);

    /**
     * Loading. The feed is currently being downloaded from the source site.
     */
    public final static int STATUS_LOADING = 0;

    /**
     * Loaded. The feed has successfuly been downloaded from the source site.
     */
    public final static int STATUS_LOADED = 1;

    /**
     * Empty. The feed has successfuly been downloaded but was empty.
     */
    public final static int STATUS_EMPTY = 2;

    /**
     * Failed To Load. The feed failed to load.
     */
    public final static int STATUS_FAILED_TO_LOAD = 3;

    // Private instance variables

    private String feedName;
    private SyndFeed feed;
    private int status;
    private SyndFeedInput input;
    private URL url;

    /**
     * Constructor.
     * 
     * @param feedName feed name
     * @param input feed input
     * @param url location
     */
    public CoreFeed(String feedName, SyndFeedInput input, URL url) {
        super("FeedLoader" + url.toExternalForm());
        this.url = url;
        this.feedName = feedName;
        this.input = input;
        this.status = STATUS_LOADING;
        start();
    }

    /**
     * Get the feed name.
     * 
     * @return feed
     */
    public String getFeedName() {
        return feedName;
    }

    /**
     * Get the feed object. This will only be available once the feed has
     * successfuly been downloaded otherwise <code>null</code> will be returned.
     * 
     * @return feed
     */
    public SyndFeed getFeed() {
        return feed;
    }

    /**
     * Get the feed status. See class documentation for details.
     * 
     * @return status
     */
    public int getStatus() {
        return status;
    }

    /* (non-Javadoc)
     * @see java.lang.Runnable#run()
     */
    public void run() {
        try {
        	if (log.isInfoEnabled())
        		log.info("Loading feed " + url);
            status = STATUS_LOADING;
            feed = input.build(new XmlReader(url));
            if (log.isInfoEnabled())
            	log.info("Loaded feed " + url);
            status = STATUS_LOADED;
        } catch (Exception e) {
            status = STATUS_FAILED_TO_LOAD;
            if(log.isDebugEnabled()) {
                // We don't care so much about this error because feeds are now dynamic
                // so its likey this will happen alot if we have not provided feeds for specific tiles
                log.error("Failed to retrieve feed from " + url + ". ", e);
            }
        }
    }
}