Java tutorial
/** * 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 javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.Serializable; import java.sql.SQLException; import org.apache.cocoon.ResourceNotFoundException; import org.apache.cocoon.caching.CacheableProcessingComponent; import org.apache.cocoon.environment.ObjectModelHelper; import org.apache.cocoon.environment.Request; import org.apache.cocoon.environment.http.HttpEnvironment; import org.apache.cocoon.util.HashUtil; import org.apache.commons.lang.reflect.FieldUtils; import org.apache.excalibur.source.SourceValidity; import org.apache.excalibur.source.impl.validity.NOPValidity; import org.dspace.app.xmlui.cocoon.AbstractDSpaceTransformer; import org.dspace.app.xmlui.utils.UIException; import org.dspace.app.xmlui.wing.Message; import org.dspace.app.xmlui.wing.WingConstants; import org.dspace.app.xmlui.wing.WingException; import org.dspace.app.xmlui.wing.element.Body; import org.dspace.app.xmlui.wing.element.Division; import org.dspace.app.xmlui.wing.element.PageMeta; import org.dspace.authorize.AuthorizeException; import org.xml.sax.Attributes; import org.xml.sax.SAXException; /** * This special component checks to see if the body element is empty (has no sub elements) and if * it is then displays some page not found text. * * @author Scott Phillips * @author Kim Shepherd */ public class PageNotFoundTransformer extends AbstractDSpaceTransformer implements CacheableProcessingComponent { /* Language Strings */ private static final Message T_title = message("xmlui.PageNotFound.title"); private static final Message T_head = message("xmlui.PageNotFound.head"); private static final Message T_para1 = message("xmlui.PageNotFound.para1"); private static final Message T_go_home = message("xmlui.general.go_home"); private static final Message T_dspace_home = message("xmlui.general.dspace_home"); /** Where the body element is stored while we wait to see if it is empty */ private SAXEvent bodyEvent; /** Have we determined that the body is empty, and hence a we should generate a page not found. */ private boolean bodyEmpty; /** * Generate the unique caching key. * This key must be unique inside the space of this component. * @return the key. */ @Override public Serializable getKey() { Request request = ObjectModelHelper.getRequest(objectModel); return HashUtil.hash(request.getSitemapURI()); } /** * Generate the cache validity object. * * The cache is always valid. * @return the validity. */ @Override public SourceValidity getValidity() { return NOPValidity.SHARED_INSTANCE; } /** * Receive notification of the beginning of a document. * @throws org.xml.sax.SAXException passed through. */ @Override public void startDocument() throws SAXException { // Reset our parameters before starting a new document. this.bodyEvent = null; this.bodyEmpty = false; super.startDocument(); } /** * Process the SAX event. * @throws org.xml.sax.SAXException passed through. * @see org.xml.sax.ContentHandler#startElement */ @Override public void startElement(String namespaceURI, String localName, String qName, Attributes attributes) throws SAXException { if (this.bodyEvent != null) { // If we have recorded the startElement for body and we are // receiving another start event, then there must be something // inside the body element, so we send the held body and carry // on as normal. sendEvent(this.bodyEvent); this.bodyEvent = null; } if (WingConstants.DRI.URI.equals(namespaceURI) && Body.E_BODY.equals(localName)) { // Save the element and see if there is anything inside the body. this.bodyEvent = SAXEvent.startElement(namespaceURI, localName, qName, attributes); return; } super.startElement(namespaceURI, localName, qName, attributes); } /** * Process the SAX event. * @throws org.xml.sax.SAXException passed through. * @see org.xml.sax.ContentHandler#endElement */ @Override public void endElement(String namespaceURI, String localName, String qName) throws SAXException { if (this.bodyEvent != null && WingConstants.DRI.URI.equals(namespaceURI) && Body.E_BODY.equals(localName)) { // If we are receiving an endElement event for body while we // still have a startElement body event recorded then // the body element must have been empty. In this case, record // that the body is empty, and send both the start and end body events. this.bodyEmpty = true; // Sending the body will trigger the Wing framework to ask // us if we want to add a body to the page. sendEvent(this.bodyEvent); this.bodyEvent = null; } super.endElement(namespaceURI, localName, qName); } /** What to add at the end of the body. * * @throws org.xml.sax.SAXException passed through. * @throws org.dspace.app.xmlui.wing.WingException passed through. * @throws org.dspace.app.xmlui.utils.UIException passed through. * @throws java.sql.SQLException passed through. * @throws java.io.IOException passed through. * @throws org.dspace.authorize.AuthorizeException passed through. * @throws org.apache.cocoon.ResourceNotFoundException * unless redirecting or body is nonempty. */ @Override public void addBody(Body body) throws SAXException, WingException, UIException, SQLException, IOException, AuthorizeException, ResourceNotFoundException { if (!isRedirect() && this.bodyEmpty) { Division notFound = body.addDivision("page-not-found", "primary"); notFound.setHead(T_head); notFound.addPara(T_para1); notFound.addPara().addXref(contextPath + "/", T_go_home); throw new ResourceNotFoundException("Page cannot be found"); } } private boolean isRedirect() { final HttpServletResponse response = (HttpServletResponse) objectModel .get(HttpEnvironment.HTTP_RESPONSE_OBJECT); try { return ((int) FieldUtils.readField(response, "statusCode", true)) == HttpServletResponse.SC_TEMPORARY_REDIRECT; } catch (Exception e) { return false; } } /** * What page metadata to add to the document. * * @throws org.xml.sax.SAXException passed through. * @throws org.dspace.app.xmlui.wing.WingException passed through. * @throws org.dspace.app.xmlui.utils.UIException passed through. * @throws java.sql.SQLException passed through. * @throws java.io.IOException passed through. * @throws org.dspace.authorize.AuthorizeException passed through. */ @Override public void addPageMeta(PageMeta pageMeta) throws SAXException, WingException, UIException, SQLException, IOException, AuthorizeException { if (this.bodyEmpty) { // Set the page title pageMeta.addMetadata("title").addContent(T_title); // Give theme a base trail pageMeta.addTrailLink(contextPath + "/", T_dspace_home); } } /** * Send the given recorded sax event. * @param event the event. * @throws org.xml.sax.SAXException passed through. */ public void sendEvent(SAXEvent event) throws SAXException { if (event.type == SAXEvent.EventType.START) { super.startElement(event.namespaceURI, event.localName, event.qName, event.attributes); } else if (event.type == SAXEvent.EventType.END) { super.endElement(event.namespaceURI, event.localName, event.qName); } } /** * This private class remembers start and end element SAX events. */ private static class SAXEvent { public enum EventType { START, END }; protected EventType type = null; protected String namespaceURI = null; protected String localName = null; protected String qName = null; protected Attributes attributes = null; /** * Create a new StartElement recorded sax event. */ public static SAXEvent startElement(String namespaceURI, String localName, String qName, Attributes attributes) { SAXEvent event = new SAXEvent(); event.type = EventType.START; event.namespaceURI = namespaceURI; event.localName = localName; event.qName = qName; event.attributes = attributes; return event; } /** * Create a new EndElement recorded sax event. */ public static SAXEvent endElement(String namespaceURI, String localName, String qName) { SAXEvent event = new SAXEvent(); event.type = EventType.END; event.namespaceURI = namespaceURI; event.localName = localName; event.qName = qName; return event; } } @Override public void recycle() { this.bodyEvent = null; super.recycle(); } }