rssgenerator.java

JSPWiki,100%Java开发的一套完整WIKI程序

/* 
    JSPWiki - a JSP-based WikiWiki clone.

    Copyright (C) 2001-2002 Janne Jalkanen ([e-mail])

    This program 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 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.ecyrd.jspwiki.rss;

import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;
import java.util.Calendar;
import java.util.List;
import java.text.SimpleDateFormat;

import com.ecyrd.jspwiki.*;
import com.ecyrd.jspwiki.attachment.Attachment;

/**
 *  Generates an RSS feed from the recent changes.
 *  <P>
 *  We use the 1.0 spec, including the wiki-specific extensions.  Wiki extensions
 *  have been defined in <A HREF="http://usemod.com/cgi-bin/mb.pl?ModWiki">UseMod:ModWiki</A>.
 *
 *  @author Janne Jalkanen
 *  @since  1.7.5.
 */
// FIXME: Merge with rss.jsp
// FIXME: Limit diff and page content size.
public class RSSGenerator
{
    private WikiEngine         m_engine;

    private String             m_channelDescription = "";
    private String             m_channelLanguage    = "en-us";

    /**
     *  Defines the property name for the RSS channel description.  Default value for the 
     *  channel description is an empty string.
     *  @since 1.7.6.
     */
    public static final String PROP_CHANNEL_DESCRIPTION = "jspwiki.rss.channelDescription";

    /**
     *  Defines the property name for the RSS channel language.  Default value for the
     *  language is "en-us".
     *  @since 1.7.6.
     */
    public static final String PROP_CHANNEL_LANGUAGE    = "jspwiki.rss.channelLanguage";

    /**
     *  Defines the property name for the RSS generator main switch.
     *  @since 1.7.6.
     */
    public static final String PROP_GENERATE_RSS        = "jspwiki.rss.generate";

    /**
     *  Defines the property name for the RSS file that the wiki should generate.
     *  @since 1.7.6.
     */
    public static final String PROP_RSSFILE             = "jspwiki.rss.fileName";

    /**
     *  Defines the property name for the RSS generation interval in seconds.
     *  @since 1.7.6.
     */
    public static final String PROP_INTERVAL            = "jspwiki.rss.interval";

    /**
     *  Initialize the RSS generator.
     */
    public RSSGenerator( WikiEngine engine, Properties properties )
        throws NoRequiredPropertyException
    {
        m_engine = engine;        

        // FIXME: This assumes a bit too much.
        if( engine.getBaseURL() == null || engine.getBaseURL().length() == 0 )
        {
            throw new NoRequiredPropertyException( "RSS requires jspwiki.baseURL to be set!",
                                                   WikiEngine.PROP_BASEURL );
        }

        m_channelDescription = properties.getProperty( PROP_CHANNEL_DESCRIPTION, 
                                                       m_channelDescription );
        m_channelLanguage    = properties.getProperty( PROP_CHANNEL_LANGUAGE,
                                                       m_channelLanguage );
    }

    /**
     *  Does the required formatting and entity replacement for XML.
     */
    public static String format( String s )
    {
        s = TextUtil.replaceString( s, "&", "&amp;" );
        s = TextUtil.replaceString( s, "<", "&lt;" );
        s = TextUtil.replaceString( s, "]]>", "]]&gt;" );

        return s.trim();
    }

    private String getAuthor( WikiPage page )
    {
        String author = page.getAuthor();

        if( author == null ) author = "An unknown author";

        return author;
    }

    private String getAttachmentDescription( Attachment att )
    {
        String author = getAuthor(att);

        if( att.getVersion() != 1 )
        {
            return (author+" uploaded a new version of this attachment on "+att.getLastModified() );
        }
        else
        {
            return (author+" created this attachment on "+att.getLastModified() );
        }
    }

    private String getPageDescription( WikiPage page )
    {
        StringBuffer buf = new StringBuffer();
        String author = getAuthor(page);

        if( page.getVersion() > 1 )
        {
            String diff = m_engine.getDiff( page.getName(),
                                            page.getVersion()-1,
                                            page.getVersion() );

            buf.append(author+" changed this page on "+page.getLastModified()+":<br /><hr /><br />" );
            buf.append(diff);
        }
        else
        {
            buf.append(author+" created this page on "+page.getLastModified()+":<br /><hr /><br />" );
            buf.append(m_engine.getHTML( page.getName() ));
        }

        return buf.toString();
    }

    private String getEntryDescription( WikiPage page )
    {
        String res;

        if( page instanceof Attachment ) 
        {
            res = getAttachmentDescription( (Attachment)page );
        }
        else
        {
            res = getPageDescription( page );
        }

        return res;
    }

    private String getEntryTitle( WikiPage page )
    {
        return page.getName();
    }

    /**
     *  Generates the RSS resource.  You probably want to output this
     *  result into a file or something, or serve as output from a servlet.
     */
    public String generate()
    {
        StringBuffer result = new StringBuffer();
        SimpleDateFormat iso8601fmt = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");

        //
        //  Preamble
        //
        result.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");

        result.append("<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\n"+
                      "   xmlns=\"http://purl.org/rss/1.0/\"\n"+
                      "   xmlns:dc=\"http://purl.org/dc/elements/1.1/\"\n"+
                      "   xmlns:wiki=\"http://purl.org/rss/1.0/modules/wiki/\">\n");

        //
        //  Channel.
        //

        result.append(" <channel rdf:about=\""+m_engine.getBaseURL()+"\">\n");

        result.append("  <title>").append(m_engine.getApplicationName()).append("</title>\n");

        // FIXME: This might fail in case the base url is not defined.
        result.append("  <link>").append(m_engine.getBaseURL()).append("</link>\n");

        result.append("  <description>");
        result.append( format(m_channelDescription) );
        result.append("</description>\n");
        
        result.append("  <language>");
        result.append( m_channelLanguage );
        result.append("</language>\n");

        //
        //  Now, list items.
        //

        Collection changed = m_engine.getRecentChanges();

        //  We need two lists, which is why we gotta make a separate list if
        //  we want to do just a single pass.
        StringBuffer itemBuffer = new StringBuffer();

        result.append("  <items>\n   <rdf:Seq>\n");

        int items = 0;
        for( Iterator i = changed.iterator(); i.hasNext() && items < 15; items++ )
        {
            WikiPage page = (WikiPage) i.next();

            String encodedName = m_engine.encodeName(page.getName());

            String url;

            if( page instanceof Attachment )
            {
                url  = m_engine.getAttachmentURL( page.getName() );
            }
            else
            {
                url  = m_engine.getViewURL(page.getName());
            }

            result.append("    <rdf:li rdf:resource=\""+url+"\" />\n");