historyiteratortag.java

wiki建站资源 java编写的 很好用

/* 
    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.tags;

import java.io.IOException;
import java.util.Collection;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;

import org.apache.log4j.Logger;

import com.ecyrd.jspwiki.WikiEngine;
import com.ecyrd.jspwiki.WikiContext;
import com.ecyrd.jspwiki.WikiPage;
import com.ecyrd.jspwiki.providers.ProviderException;

/**
 *  Iterates through tags.
 *
 *  <P><B>Attributes</B></P>
 *  <UL>
 *    <LI>page - Page name to refer to.  Default is the current page.
 *  </UL>
 *
 *  @author Janne Jalkanen
 *  @since 2.0
 */

// FIXME: Too much in common with IteratorTag - REFACTOR
public class HistoryIteratorTag
    extends IteratorTag
{
    static    Logger    log = Logger.getLogger( HistoryIteratorTag.class );

    public final int doStartTag()
    {
        m_wikiContext = (WikiContext) pageContext.getAttribute( WikiTagBase.ATTR_CONTEXT,
                                                                PageContext.REQUEST_SCOPE );

        WikiEngine engine = m_wikiContext.getEngine();
        WikiPage   page;

        page = m_wikiContext.getPage();

        try
        {
            if( page != null && engine.pageExists(page) )
            {
                Collection versions = engine.getVersionHistory( page.getName() );

                if( versions == null )
                {
                    // There is no history
                    return SKIP_BODY;
                }

                m_iterator = versions.iterator();

                if( m_iterator.hasNext() )
                {
                    WikiContext context = (WikiContext)m_wikiContext.clone();
                    context.setPage( (WikiPage)m_iterator.next() );
                    pageContext.setAttribute( WikiTagBase.ATTR_CONTEXT,
                                              context,
                                              PageContext.REQUEST_SCOPE );
                    pageContext.setAttribute( getId(),
                                              context.getPage() );
                }
                else
                {
                    return SKIP_BODY;
                }
            }

            return EVAL_BODY_TAG;
        }
        catch( ProviderException e )
        {
            log.fatal("Provider failed while trying to iterator through history",e);
            // FIXME: THrow something.
        }

        return SKIP_BODY;
    }

    public final int doAfterBody()
    {
        if( bodyContent != null )
        {
            try
            {
                JspWriter out = getPreviousOut();
                out.print(bodyContent.getString());
                bodyContent.clearBody();
            }
            catch( IOException e )
            {
                log.error("Unable to get inner tag text", e);
                // FIXME: throw something?
            }
        }

        if( m_iterator != null && m_iterator.hasNext() )
        {
            WikiContext context = (WikiContext)m_wikiContext.clone();
            context.setPage( (WikiPage)m_iterator.next() );
            pageContext.setAttribute( WikiTagBase.ATTR_CONTEXT,
                                      context,
                                      PageContext.REQUEST_SCOPE );
            pageContext.setAttribute( getId(),
                                      context.getPage() );
            return EVAL_BODY_TAG;
        }
        else
        {
            return SKIP_BODY;
        }
    }
}