Java tutorial
/********************************************************************************** * $URL$ * $Id$ *********************************************************************************** * * Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009 The Sakai Foundation * * Licensed under the Educational Community 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 * * http://www.opensource.org/licenses/ECL-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.sakaiproject.tool.assessment.qti.util; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.StringReader; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Result; import javax.xml.transform.Source; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import org.apache.commons.collections.ReferenceMap; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.jaxen.JaxenException; import org.jaxen.XPath; import org.jaxen.dom.DOMXPath; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.DOMOutputter; import org.w3c.dom.Attr; import org.w3c.dom.CharacterData; import org.w3c.dom.DOMException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.Text; import org.w3c.dom.bootstrap.DOMImplementationRegistry; import org.w3c.dom.ls.DOMImplementationLS; import org.w3c.dom.ls.LSOutput; import org.w3c.dom.ls.LSSerializer; import org.xml.sax.SAXException; /** * <p>Copyright: Copyright (c) 2004</p> * <p>Organization: Sakai Project</p> * @author rshastri * @author Ed Smiley esmiley@stanford.edu * @version $Id$ */ public class XmlStringBuffer implements java.io.Serializable { private static Log log = LogFactory.getLog(XmlStringBuffer.class); /** * Explicitly setting serialVersionUID insures future versions can be * successfully restored. It is essential this variable name not be changed * to SERIALVERSIONUID, as the default serialization methods expects this * exact name. */ private static final long serialVersionUID = 1; //The following need not be persisted and so are declared transient private transient Document document = null; private transient DocumentBuilder builder = null; private transient ReferenceMap cache = null; private StringBuffer xml; /** * Constructor to be accessed by subclasses. */ protected XmlStringBuffer() { this.xml = new StringBuffer(); } /** * Constructs an XmlStringBuffer whose initial value is String. * * @param xml XML string */ public XmlStringBuffer(String xml) { this.xml = new StringBuffer(xml); } /** * Constructs an XmlStringBuffer whose initial value is Document * * @param document XML document */ public XmlStringBuffer(Document document) { this.document = document; } /** * Constructs an XmlStringBuffer whose initial value is Document * * @param jdomDoc * * @deprecated using XmlStringBuffer(org.w3c.dom.Document document) instead. */ public XmlStringBuffer(org.jdom.Document jdomDoc) { try { this.document = new DOMOutputter().output(jdomDoc); } catch (JDOMException e) { log.error(e.getMessage(), e); } } /** * Clears the xml */ public final void clear() { this.xml.setLength(0); this.reset(); } /** * replace the current xml with the given string * * @param xml XML replacement string * * @deprecated */ public final void replace(String xml) { this.xml = new StringBuffer(xml); this.reset(); } /** * Get a document * * @return document * * @throws ParserConfigurationException * @throws SAXException * @throws IOException */ public final Document getDocument() throws ParserConfigurationException, SAXException, IOException { if (this.document == null) { this.parseContent(); } return this.document; } /** * internal * * @return reference map */ private ReferenceMap getCache() { if (this.cache == null) { this.cache = new ReferenceMap(); } return this.cache; } /** * inernal, clear cache */ private void clearCache() { if (this.cache == null) { this.cache = new ReferenceMap(); } else { this.cache.clear(); } } /** * parse content to JDOM * * @return JDOM document * * @throws JDOMException = * @throws IOException */ /* private final org.jdom.Document parseContentToJDOM() throws JDOMException, IOException { if(log.isDebugEnabled()) { log.debug("parseContentToJDOM()"); } String xmlString = this.stringValue(); org.jdom.Document result = null; try { SAXBuilder saxbuilder = new SAXBuilder(); result = saxbuilder.build(new StringReader(xmlString)); } catch(JDOMException ex) { log.error("Exception thrown while parsing XML:\n" + ex.getMessage(), ex); throw ex; } catch(IOException ie) { log.error("Exception thrown while parsing XML:\n" + ie.getMessage(), ie); throw ie; } return result; } */ /** * parse the content * * @throws ParserConfigurationException * @throws SAXException * @throws IOException */ private final void parseContent() throws ParserConfigurationException, SAXException, IOException { if (log.isDebugEnabled()) { log.debug("parseContent()"); } this.clearCache(); DocumentBuilderFactory dbfi = null; DocumentBuilder builder = null; StringReader sr = null; org.xml.sax.InputSource is = null; try { dbfi = DocumentBuilderFactory.newInstance(); builder = dbfi.newDocumentBuilder(); String s = this.xml.toString(); if (s == null) { log.warn("string value null"); s = ""; } sr = new StringReader(s); is = new org.xml.sax.InputSource(sr); this.document = builder.parse(is); } catch (ParserConfigurationException e) { log.error(e.getMessage(), e); throw e; } catch (SAXException e) { log.error(e.getMessage(), e); log.error("DocumentBuilderFactory dbfi = " + dbfi); log.error("StringReader sr = " + sr); log.error("InputSource is = " + is); log.error("StringBuffer xml = " + this.xml); throw e; } catch (IOException e) { log.error(e.getMessage(), e); throw e; } } /** * string value of document * * @return the string */ public final String stringValue() { if (log.isDebugEnabled()) { log.debug("stringValue()"); } if (document == null) { return this.xml.toString(); } else { ByteArrayOutputStream out = new ByteArrayOutputStream(); try { DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance(); DOMImplementationLS impl = (DOMImplementationLS) registry.getDOMImplementation("LS"); LSSerializer writer = impl.createLSSerializer(); writer.getDomConfig().setParameter("format-pretty-print", Boolean.TRUE); LSOutput output = impl.createLSOutput(); output.setByteStream(out); writer.write(document, output); } catch (Exception e) { log.error(e.getMessage(), e); } return out.toString(); } } /** * is the xml empty? * * @return true/false */ public final boolean isEmpty() { return ((this.xml == null) || (this.xml.length() == 0)); } /** * */ private void reset() { this.document = null; this.cache = null; } /** * xpath lookup * * @param xpath * @param type * * @return value */ public String selectSingleValue(String xpath, String type) { // user passes the if its an element or attribute String value = null; List list = this.selectNodes(xpath); if (list != null) { int no = list.size(); if (list.size() > 0) { if ((type != null) && type.equals("element")) { Element element = (Element) list.get(0); CharacterData elementText = (CharacterData) element.getFirstChild(); Integer getTime = null; if ((elementText != null) && (elementText.getNodeValue() != null) && (elementText.getNodeValue().trim().length() > 0)) { value = elementText.getNodeValue(); } } if ((type != null) && type.equals("attribute")) { Attr attr = (Attr) list.get(0); CharacterData elementText = (CharacterData) attr.getFirstChild(); Integer getTime = null; if ((elementText != null) && (elementText.getNodeValue() != null) && (elementText.getNodeValue().trim().length() > 0)) { value = elementText.getNodeValue(); } } } } return value; } /** * get nodes * * @param xpath * * @return list of nodes */ public final List selectNodes(String xpath) { if (log.isDebugEnabled()) { log.debug("selectNodes(String " + xpath + ")"); } List result = null; try { XPath path = new DOMXPath(xpath); result = path.selectNodes(this.getDocument()); } catch (JaxenException je) { log.error(je.getMessage(), je); } catch (ParserConfigurationException e) { log.error(e.getMessage(), e); } catch (SAXException e) { log.error(e.getMessage(), e); } catch (IOException e) { log.error(e.getMessage(), e); } if (result == null) { result = new ArrayList(); } return result; } public String getValueOf(String xpath) { try { XPath path = new DOMXPath(xpath); return path.stringValueOf(this.getDocument()); } catch (Exception e) { log.error(e.getMessage(), e); return null; } } /** * perform Update on this object * * @param xpath :- xpath and * @param value :- Value of xpath * * @return XmlStringBuffer * * @throws DOMException * @throws Exception */ // Rashmi Aug 19th changed by Pamela on Sept 10th. // Rashmi - replacing updateJDOM as on Sep 15 public final XmlStringBuffer update(String xpath, String value) throws DOMException, Exception { if (log.isDebugEnabled()) { log.debug("update(String " + xpath + ", String " + value + ")"); } try { Element newElement = null; Attr newAttribute = null; List newElementList = this.selectNodes(xpath); //only look at the last part of the path int aIndex = xpath.lastIndexOf("/"); if (aIndex == -1) { aIndex = 0; } aIndex = xpath.indexOf("@", aIndex); int size = newElementList.size(); if (size > 1) { log.info("UPDATING MORE THAN ONE ELEMENT"); } if ((aIndex == -1) && (size != 0)) { for (int i = 0; i < size; i++) { newElement = (Element) newElementList.get(i); Node childNode = newElement.getFirstChild(); if (childNode == null) { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.newDocument(); Text newElementText = document.createTextNode(newElement.getNodeName()); newElementText.setNodeValue(value); Text clonedText = (Text) newElement.getOwnerDocument().importNode(newElementText, true); newElement.appendChild(clonedText); } else { CharacterData newElementText = (CharacterData) newElement.getFirstChild(); newElementText.setNodeValue(value); } } } if ((aIndex != -1) && (size != 0)) { newAttribute = (Attr) newElementList.set(0, null); if (newAttribute != null) { newAttribute.setValue(value); } } } catch (Exception ex) { log.error(ex.getMessage(), ex); } return this; } /** * update element, xpath * * @param xpath * @param element */ public final void update(String xpath, Element element) { if (log.isDebugEnabled()) { log.debug("update(String " + xpath + ", Element " + element + ")"); } List itemResults = this.selectNodes(xpath); Iterator iterator = itemResults.iterator(); while (iterator.hasNext()) { Element node = (Element) iterator.next(); Element replacement = (Element) node.getOwnerDocument().importNode(element, true); node.getParentNode().replaceChild(replacement, node); } if (itemResults.size() == 0) { String parentPath = xpath.substring(0, xpath.lastIndexOf("/")); addElement(parentPath, element); } } /** * DOCUMENT ME! * * @param xpath * @param element * * @deprecated addElement(String, org.w3c.dom.Element) */ public final void addJDOMElement(String xpath, org.jdom.Element element) { try { List nodes = this.selectNodes(xpath); int size = nodes.size(); for (int i = 0; i < size; i++) { org.jdom.Element node = (org.jdom.Element) nodes.get(i); node.addContent(element); } } catch (Exception ex) { log.error(ex.getMessage(), ex); } } /** * insert element * * @param afterNode * @param parentXpath * @param childXpath */ public void insertElement(String afterNode, String parentXpath, String childXpath) { try { String nextXpath = parentXpath + "/" + afterNode; //************************************************************* DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.newDocument(); Element element = document.createElement(childXpath); //************************************************************** Element parent = null; List parentNodes = this.selectNodes(parentXpath); Iterator iteratorNext = parentNodes.iterator(); while (iteratorNext.hasNext()) { parent = (Element) iteratorNext.next(); } if (parent != null) { List nodes = this.selectNodes(nextXpath); Iterator iterator = nodes.iterator(); Element nextSibling = null; while (iterator.hasNext()) { nextSibling = (Element) iterator.next(); } if ((nextSibling != null) && !nextSibling.getOwnerDocument().equals(element.getOwnerDocument())) { element = (Element) parent.getOwnerDocument().importNode(element, true); parent.insertBefore(element, nextSibling); } } } catch (ParserConfigurationException pce) { log.error("Exception thrown from insertElement() : " + pce.getMessage()); pce.printStackTrace(); } } /** * * * @param parentXpath * @param childXpath */ public final void add(String parentXpath, String childXpath) { Element childElement = createChildElement(childXpath); this.addElement(parentXpath, childElement); } /** * create child * * @param childXpath * * @return */ protected final Element createChildElement(String childXpath) { int index = childXpath.indexOf("/"); String elementName = childXpath; String subChildXpath = null; Element element = null; Element child = null; if (index > 0) { elementName = childXpath.substring(0, index); subChildXpath = childXpath.substring(index + 1); child = createChildElement(subChildXpath); } try { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.newDocument(); element = document.createElement(elementName); if (child != null) { Node importedNode = document.importNode(child, true); element.appendChild(importedNode); } } catch (ParserConfigurationException pce) { log.error("Exception thrown from createChildElement(): " + pce.getMessage()); pce.printStackTrace(); } return element; } /** * add element * * @param parentXpath * @param element */ public final void addElement(String parentXpath, Element element) { if (log.isDebugEnabled()) { log.debug("addElement(String " + parentXpath + ", Element " + element + ")"); } List<Element> nodes = this.selectNodes(parentXpath); for (Element parent : nodes) { if (!parent.getOwnerDocument().equals(element.getOwnerDocument())) { element = (Element) parent.getOwnerDocument().importNode(element, true); } parent.appendChild(element); } } /** * add attribute * * @param elementXpath * @param attributeName */ public final void addAttribute(String elementXpath, String attributeName) { if (log.isDebugEnabled()) { log.debug("addAttribute(String " + elementXpath + ", String" + attributeName + ")"); } List nodes = this.selectNodes(elementXpath); int size = nodes.size(); for (int i = 0; i < size; i++) { Element element = (Element) nodes.get(i); element.setAttribute(attributeName, ""); } } /** * remove element * * @param xpath */ public final void removeElement(String xpath) { if (log.isDebugEnabled()) { log.debug("removeElement(String " + xpath + ")"); } List nodes = this.selectNodes(xpath); Iterator iterator = nodes.iterator(); while (iterator.hasNext()) { Node node = (Node) iterator.next(); Node parent = node.getParentNode(); parent.removeChild(node); } } /** * Synchronizes object prior to serialization * * @param out ObjectOutputStream * * @throws IOException */ private void writeObject(java.io.ObjectOutputStream out) throws IOException { if (log.isDebugEnabled()) { log.debug("writeObject(ObjectOutputStream " + out + ")"); } this.xml = new StringBuffer(this.stringValue()); out.defaultWriteObject(); } }