/*
* IfModifiedSinceSelector.java
*
* Version: $Revision: 3705 $
*
* Date: $Date: 2009-04-11 13:02:24 -0400 (Sat, 11 Apr 2009) $
*
* Copyright (c) 2002-2005, Hewlett-Packard Company and Massachusetts
* Institute of Technology. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the Hewlett-Packard Company nor the name of the
* Massachusetts Institute of Technology nor the names of their
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
package org.dspace.app.xmlui.aspect.general;
import java.util.Map;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.selection.Selector;
import org.apache.log4j.Logger;
import org.dspace.app.xmlui.utils.HandleUtil;
import org.dspace.content.DSpaceObject;
import org.dspace.content.Item;
import org.dspace.core.Constants;
/**
* This simple selector looks for the If-Modified-Since header, and
* returns true if the Item in the request has not been modified since that
* date. The expression is ignored since the test is inherent in the request.
*
* Typical sitemap usage:
*
* <map:match type="HandleTypeMatcher" pattern="item">
* <map:select type="IfModifiedSinceSelector">
* <map:when test="true">
* <map:act type="NotModifiedAction"/>
* <map:serialize/>
* </map:when>
* <map:otherwise>
* <map:transform type="ItemViewer"/>
* <map:serialize type="xml"/>
* </map:otherwise>
* </map:select>
* </map:match>
*
* @author Larry Stone
*/
public class IfModifiedSinceSelector implements Selector
{
private static Logger log = Logger.getLogger(IfModifiedSinceSelector.class);
/**
* Check for If-Modified-Since header on request,
* and returns true if the Item should *not* be sent, i.e.
* if the response status should be 304 (HttpServletResponse.SC_NOT_MODIFIED).
*
* @param expression is ignored
* @param objectModel
* environment passed through via cocoon
* @return null or map containing value of sitemap parameter 'pattern'
*/
public boolean select(String expression, Map objectModel,
Parameters parameters)
{
try
{
Request request = ObjectModelHelper.getRequest(objectModel);
DSpaceObject dso = HandleUtil.obtainHandle(objectModel);
if (dso.getType() == Constants.ITEM)
{
Item item = (Item) dso;
long modSince = request.getDateHeader("If-Modified-Since");
if (modSince != -1 && item.getLastModified().getTime() < modSince)
{
return true;
}
}
return false;
}
catch (Exception e)
{
log.error("Error selecting based on If-Modified-Since: "+e.toString());
return false;
}
}
}