/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
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;
}
}
}