Java tutorial
/** * Licensed to Apereo under one or more contributor license * agreements. See the NOTICE file distributed with this work * for additional information regarding copyright ownership. * Apereo licenses this file to you under the Apache License, * Version 2.0 (the "License"); you may not use this file * except in compliance with the License. You may obtain a * copy of the License at the following location: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apereo.portal.layout.dlm; import java.io.StringWriter; import java.util.HashSet; import java.util.List; import java.util.Set; import javax.xml.transform.Result; import javax.xml.transform.Source; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerFactory; import javax.xml.transform.TransformerFactoryConfigurationError; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apereo.portal.AuthorizationException; import org.apereo.portal.EntityIdentifier; import org.apereo.portal.security.IAuthorizationPrincipal; import org.apereo.portal.security.IPerson; import org.apereo.portal.services.AuthorizationService; import org.apereo.portal.utils.DocumentFactory; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; /** Performs merging of layout fragments into a single document containing * all incorporated layout fragment elements from the set of fragments * passed in. This merge is trivial, appending all children of each * fragment into the composite document and recording their identifiers * in the document identifier cache. No changes are made to the source * fragments passed in. * * @since uPortal 2.5 */ public class ILFBuilder { private static final Log LOG = LogFactory.getLog(ILFBuilder.class); public static Document constructILF(Document PLF, List<Document> sequence, IPerson person) { if (LOG.isDebugEnabled()) { LOG.debug("Constructing ILF for IPerson='" + person + "'"); } // first construct the destination document and root element. The root // element should be a complete copy of the PLF's root including its // node identifier in the new document. This requires the use of // the implementation class to set the identifier for that node // in the document. Document result = DocumentFactory.getThreadDocument(); Element plfLayout = PLF.getDocumentElement(); Element ilfLayout = (Element) result.importNode(plfLayout, false); result.appendChild(ilfLayout); Element plfRoot = (Element) plfLayout.getFirstChild(); Element ilfRoot = (Element) result.importNode(plfRoot, false); ilfLayout.appendChild(ilfRoot); if (ilfRoot.getAttribute(Constants.ATT_ID) != null) ilfRoot.setIdAttribute(Constants.ATT_ID, true); // build the auth principal for determining if pushed channels can be // used by this user EntityIdentifier ei = person.getEntityIdentifier(); AuthorizationService authS = AuthorizationService.instance(); IAuthorizationPrincipal ap = authS.newPrincipal(ei.getKey(), ei.getType()); // now merge fragments one at a time into ILF document for (final Document document : sequence) { mergeFragment(document, result, ap); } return result; } /** * Passes the layout root of each of these documents to mergeChildren * causing all children of newLayout to be merged into compositeLayout * following merging protocal for distributed layout management. * @throws AuthorizationException **/ public static void mergeFragment(Document fragment, Document composite, IAuthorizationPrincipal ap) throws AuthorizationException { Element fragmentLayout = fragment.getDocumentElement(); Element fragmentRoot = (Element) fragmentLayout.getFirstChild(); Element compositeLayout = composite.getDocumentElement(); Element compositeRoot = (Element) compositeLayout.getFirstChild(); mergeChildren(fragmentRoot, compositeRoot, ap, new HashSet()); } /** * @param source parent of children * @param dest receiver of children * @param ap User's authorization principal for determining if they can view a channel * @param visitedNodes A Set of nodes from the source tree that have been visited to get to this node, used to ensure a loop doesn't exist in the source tree. * @throws AuthorizationException */ private static void mergeChildren(Element source, Element dest, IAuthorizationPrincipal ap, Set visitedNodes) throws AuthorizationException { //Record this node in the visited nodes set. If add returns false a loop has been detected if (!visitedNodes.add(source)) { final String msg = "mergeChildren has encountered a loop in the source DOM. currentNode='" + source + "', currentDepth='" + visitedNodes.size() + "', visitedNodes='" + visitedNodes + "'"; final IllegalStateException ise = new IllegalStateException(msg); LOG.error(msg, ise); printNodeToDebug(source, "Source"); printNodeToDebug(dest, "Dest"); throw ise; } Document destDoc = dest.getOwnerDocument(); Node item = source.getFirstChild(); while (item != null) { if (item instanceof Element) { Element child = (Element) item; Element newChild = null; if (null != child && mergeAllowed(child, ap)) { newChild = (Element) destDoc.importNode(child, false); dest.appendChild(newChild); String id = newChild.getAttribute(Constants.ATT_ID); if (id != null && !id.equals("")) newChild.setIdAttribute(Constants.ATT_ID, true); mergeChildren(child, newChild, ap, visitedNodes); } } item = item.getNextSibling(); } //Remove this node from the visited nodes set visitedNodes.remove(source); } /** * Tests to see if channels to be merged from ILF can be rendered by the * end user. If not then they are discarded from the merge. * * @param child * @param person * @return * @throws AuthorizationException * @throws NumberFormatException */ private static boolean mergeAllowed(Element child, IAuthorizationPrincipal ap) throws AuthorizationException { if (!child.getTagName().equals("channel")) return true; String channelPublishId = child.getAttribute("chanID"); return ap.canRender(channelPublishId); } private static void printNodeToDebug(Node n, String name) throws TransformerFactoryConfigurationError { if (!LOG.isDebugEnabled()) { return; } final StringWriter writer = new StringWriter(); try { final TransformerFactory transFactory = TransformerFactory.newInstance(); final Transformer trans = transFactory.newTransformer(); final Source xmlSource = new DOMSource(n); final Result transResult = new StreamResult(writer); trans.transform(xmlSource, transResult); final String xmlStr = writer.toString(); LOG.debug(name + " DOM Tree:\n\n" + xmlStr); } catch (Exception e) { LOG.error("Error printing out " + name + " DOM Tree", e); final String xmlStr = writer.toString(); LOG.debug("Partial " + name + " DOM Tree:\n\n" + xmlStr); } } }