archive/net.sourceforge.phpeclipse.wiki/src/net/sourceforge/phpeclipse/wiki/internal/XMLMemento.java

   1 /**********************************************************************
   2  * Copyright (c) 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - Initial API and implementation
  10  **********************************************************************/
  11 package net.sourceforge.phpeclipse.wiki.internal;
  12
  13 import java.io.*;
  14 import java.util.*;
  15 import java.net.URL;
  16 import org.w3c.dom.*;
  17 import org.xml.sax.*;
  18
  19 import javax.xml.parsers.*;
  20 import javax.xml.transform.*;
  21 import javax.xml.transform.dom.DOMSource;
  22 import javax.xml.transform.stream.StreamResult;
  23 /**
  24  * A Memento is a class independent container for persistence
  25  * info.  It is a reflection of 3 storage requirements.
  26  *
  27  * 1)   We need the ability to persist an object and restore it.
  28  * 2)   The class for an object may be absent.  If so we would
  29  *      like to skip the object and keep reading.
  30  * 3)   The class for an object may change.  If so the new class
  31  *      should be able to read the old persistence info.
  32  *
  33  * We could ask the objects to serialize themselves into an
  34  * ObjectOutputStream, DataOutputStream, or Hashtable.  However
  35  * all of these approaches fail to meet the second requirement.
  36  *
  37  * Memento supports binary persistance with a version ID.
  38  */
  39 public final class XMLMemento implements IMemento {
  40         private Document factory;
  41         private Element element;
  42
  43         /**
  44          * Answer a memento for the document and element.  For simplicity
  45          * you should use createReadRoot and createWriteRoot to create the initial
  46          * mementos on a document.
  47          */
  48         public XMLMemento(Document doc, Element el) {
  49                 factory = doc;
  50                 element = el;
  51         }
  52
  53         /**
  54          * @see IMemento.
  55          */
  56         public IMemento createChild(String type) {
  57                 Element child = factory.createElement(type);
  58                 element.appendChild(child);
  59                 return new XMLMemento(factory, child);
  60         }
  61
  62         /**
  63          * @see IMemento.
  64          */
  65         public IMemento createChild(String type, String id) {
  66                 Element child = factory.createElement(type);
  67                 child.setAttribute(TAG_ID, id);
  68                 element.appendChild(child);
  69                 return new XMLMemento(factory, child);
  70         }
  71
  72         /**
  73          * Create a Document from a Reader and answer a root memento for reading
  74          * a document.
  75          */
  76         protected static XMLMemento createReadRoot(Reader reader) {
  77                 Document document = null;
  78                 try {
  79                         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
  80                         DocumentBuilder parser = factory.newDocumentBuilder();
  81                         document = parser.parse(new InputSource(reader));
  82                         Node node = document.getFirstChild();
  83                         if (node instanceof Element)
  84                                 return new XMLMemento(document, (Element) node);
  85                 } catch (ParserConfigurationException e) {
  86                 } catch (IOException e) {
  87                 } catch (SAXException e) {
  88                 } finally {
  89                         try {
  90                                 reader.close();
  91                         } catch (Exception e) { }
  92                 }
  93                 return null;
  94         }
  95
  96         /**
  97          * Answer a root memento for writing a document.
  98          */
  99         public static XMLMemento createWriteRoot(String type) {
 100                 Document document;
 101                 try {
 102                         document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
 103                         Element element = document.createElement(type);
 104                         document.appendChild(element);
 105                         return new XMLMemento(document, element);
 106                 } catch (ParserConfigurationException e) {
 107                         throw new Error(e);
 108                 }
 109         }
 110
 111         /**
 112          * @see IMemento.
 113          */
 114         public IMemento getChild(String type) {
 115                 // Get the nodes.
 116                 NodeList nodes = element.getChildNodes();
 117                 int size = nodes.getLength();
 118                 if (size == 0)
 119                         return null;
 120
 121                 // Find the first node which is a child of this node.
 122                 for (int nX = 0; nX < size; nX ++) {
 123                         Node node = nodes.item(nX);
 124                         if (node instanceof Element) {
 125                                 Element element2 = (Element)node;
 126                                 if (element2.getNodeName().equals(type))
 127                                         return new XMLMemento(factory, element2);
 128                         }
 129                 }
 130
 131                 // A child was not found.
 132                 return null;
 133         }
 134
 135         /**
 136          * @see IMemento.
 137          */
 138         public IMemento [] getChildren(String type) {
 139                 // Get the nodes.
 140                 NodeList nodes = element.getChildNodes();
 141                 int size = nodes.getLength();
 142                 if (size == 0)
 143                         return new IMemento[0];
 144
 145                 // Extract each node with given fType.
 146                 ArrayList list = new ArrayList(size);
 147                 for (int nX = 0; nX < size; nX ++) {
 148                         Node node = nodes.item(nX);
 149                         if (node instanceof Element) {
 150                                 Element element2 = (Element)node;
 151                                 if (element2.getNodeName().equals(type))
 152                                         list.add(element2);
 153                         }
 154                 }
 155
 156                 // Create a memento for each node.
 157                 size = list.size();
 158                 IMemento [] results = new IMemento[size];
 159                 for (int x = 0; x < size; x ++) {
 160                         results[x] = new XMLMemento(factory, (Element)list.get(x));
 161                 }
 162                 return results;
 163         }
 164
 165         /**
 166          * Return the contents of this memento as a byte array.
 167          *
 168          * @return byte[]
 169          */
 170         public byte[] getContents() throws IOException {
 171                 ByteArrayOutputStream out = new ByteArrayOutputStream();
 172                 save(out);
 173                 return out.toByteArray();
 174         }
 175
 176         /**
 177          * Returns an input stream for writing to the disk with a local locale.
 178          *
 179          * @return java.io.InputStream
 180          */
 181         public InputStream getInputStream() throws IOException {
 182                 ByteArrayOutputStream out = new ByteArrayOutputStream();
 183                 save(out);
 184                 return new ByteArrayInputStream(out.toByteArray());
 185         }
 186
 187         /**
 188          * @see IMemento.
 189          */
 190         public Float getFloat(String key) {
 191                 Attr attr = element.getAttributeNode(key);
 192                 if (attr == null)
 193                         return null;
 194                 String strValue = attr.getValue();
 195                 try {
 196                         return new Float(strValue);
 197                 } catch (NumberFormatException e) {
 198                         return null;
 199                 }
 200         }
 201
 202         /**
 203          * @see IMemento.
 204          */
 205         public String getId() {
 206                 return element.getAttribute(TAG_ID);
 207         }
 208
 209         /**
 210          * @see IMemento.
 211          */
 212         public String getName() {
 213                 return element.getNodeName();
 214         }
 215
 216         /**
 217          * @see IMemento.
 218          */
 219         public Integer getInteger(String key) {
 220                 Attr attr = element.getAttributeNode(key);
 221                 if (attr == null)
 222                         return null;
 223                 String strValue = attr.getValue();
 224                 try {
 225                         return new Integer(strValue);
 226                 } catch (NumberFormatException e) {
 227                         return null;
 228                 }
 229         }
 230
 231         /**
 232          * @see IMemento.
 233          */
 234         public String getString(String key) {
 235                 Attr attr = element.getAttributeNode(key);
 236                 if (attr == null)
 237                         return null;
 238                 return attr.getValue();
 239         }
 240
 241         public List getNames() {
 242                 NamedNodeMap map = element.getAttributes();
 243                 int size = map.getLength();
 244                 List list = new ArrayList();
 245                 for (int i = 0; i < size; i++) {
 246                         Node node = map.item(i);
 247                         String name = node.getNodeName();
 248                         list.add(name);
 249                 }
 250                 return list;
 251         }
 252
 253         /**
 254          * Loads a memento from the given filename.
 255          *
 256          * @param in java.io.InputStream
 257          * @return org.eclipse.ui.IMemento
 258          * @exception java.io.IOException
 259          */
 260         public static IMemento loadMemento(InputStream in) {
 261                 return createReadRoot(new InputStreamReader(in));
 262         }
 263
 264         /**
 265          * Loads a memento from the given filename.
 266          *
 267          * @param in java.io.InputStream
 268          * @return org.eclipse.ui.IMemento
 269          * @exception java.io.IOException
 270          */
 271         public static IMemento loadCorruptMemento(InputStream in) {
 272                 Document document = null;
 273                 try {
 274                         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 275                         DocumentBuilder parser = factory.newDocumentBuilder();
 276                         document = parser.parse(in);
 277                         Node node = document.getFirstChild();
 278                         if (node instanceof Element)
 279                                 return new XMLMemento(document, (Element) node);
 280                 } catch (ParserConfigurationException e) {
 281                 } catch (IOException e) {
 282                 } catch (SAXException e) {
 283                 } finally {
 284                         try {
 285                                 in.close();
 286                         } catch (Exception e) { }
 287                 }
 288                 return null;
 289         }
 290
 291         /**
 292          * Loads a memento from the given filename.
 293          *
 294          * @param filename java.lang.String
 295          * @return org.eclipse.ui.IMemento
 296          * @exception java.io.IOException
 297          */
 298         public static IMemento loadMemento(String filename) throws IOException {
 299                 return XMLMemento.createReadRoot(new FileReader(filename));
 300         }
 301
 302         /**
 303          * Loads a memento from the given filename.
 304          *
 305          * @param url java.net.URL
 306          * @return org.eclipse.ui.IMemento
 307          * @exception java.io.IOException
 308          */
 309         public static IMemento loadMemento(URL url) throws IOException {
 310                 return XMLMemento.createReadRoot(new InputStreamReader(url.openStream()));
 311         }
 312
 313         /**
 314          * @see IMemento.
 315          */
 316         private void putElement(Element element2) {
 317                 NamedNodeMap nodeMap = element2.getAttributes();
 318                 int size = nodeMap.getLength();
 319                 for (int i = 0; i < size; i++){
 320                         Attr attr = (Attr)nodeMap.item(i);
 321                         putString(attr.getName(),attr.getValue());
 322                 }
 323
 324                 NodeList nodes = element2.getChildNodes();
 325                 size = nodes.getLength();
 326                 for (int i = 0; i < size; i ++) {
 327                         Node node = nodes.item(i);
 328                         if (node instanceof Element) {
 329                                 XMLMemento child = (XMLMemento)createChild(node.getNodeName());
 330                                 child.putElement((Element)node);
 331                         }
 332                 }
 333         }
 334
 335         /**
 336          * @see IMemento.
 337          */
 338         public void putFloat(String key, float f) {
 339                 element.setAttribute(key, String.valueOf(f));
 340         }
 341
 342         /**
 343          * @see IMemento.
 344          */
 345         public void putInteger(String key, int n) {
 346                 element.setAttribute(key, String.valueOf(n));
 347         }
 348
 349         /**
 350          * @see IMemento.
 351          */
 352         public void putMemento(IMemento memento) {
 353                 XMLMemento xmlMemento = (XMLMemento) memento;
 354                 putElement(xmlMemento.element);
 355         }
 356
 357         /**
 358          * @see IMemento.
 359          */
 360         public void putString(String key, String value) {
 361                 if (value == null)
 362                         return;
 363                 element.setAttribute(key, value);
 364         }
 365
 366         /**
 367          * Save this Memento to a Writer.
 368          */
 369         public void save(Writer writer) throws IOException {
 370                 Result result = new StreamResult(writer);
 371                 Source source = new DOMSource(factory);
 372                 try {
 373                         Transformer transformer = TransformerFactory.newInstance().newTransformer();
 374                         transformer.setOutputProperty(OutputKeys.INDENT, "yes"); //$NON-NLS-1$
 375                         transformer.setOutputProperty(OutputKeys.METHOD, "xml"); //$NON-NLS-1$
 376                         transformer.transform(source, result);
 377                 } catch (Exception e) {
 378                         throw (IOException) (new IOException().initCause(e));
 379                 }
 380         }
 381
 382         /**
 383          * Save this Memento to a Writer.
 384          */
 385         public void save(OutputStream os) throws IOException {
 386                 Result result = new StreamResult(os);
 387                 Source source = new DOMSource(factory);
 388                 try {
 389                         Transformer transformer = TransformerFactory.newInstance().newTransformer();
 390                         transformer.setOutputProperty(OutputKeys.INDENT, "yes"); //$NON-NLS-1$
 391                         transformer.setOutputProperty(OutputKeys.METHOD, "xml"); //$NON-NLS-1$
 392                         transformer.transform(source, result);
 393                 } catch (Exception e) {
 394                         throw (IOException) (new IOException().initCause(e));
 395                 }
 396         }
 397
 398         /**
 399          * Saves the memento to the given file.
 400          *
 401          * @param filename java.lang.String
 402          * @exception java.io.IOException
 403          */
 404         public void saveToFile(String filename) throws IOException {
 405                 Writer w = null;
 406                 try {
 407                         w = new FileWriter(filename);
 408                         save(w);
 409                 } catch (IOException e) {
 410                         throw e;
 411                 } catch (Exception e) {
 412                         throw new IOException(e.getLocalizedMessage());
 413                 } finally {
 414                         if (w != null) {
 415                                 try {
 416                                         w.close();
 417                                 } catch (Exception e) { }
 418                         }
 419                 }
 420         }
 421
 422         public String saveToString() throws IOException {
 423                 ByteArrayOutputStream out = new ByteArrayOutputStream();
 424                 save(out);
 425                 return out.toString("UTF-8");
 426         }
 427
 428         /*
 429          * @see IMemento#getBoolean(String)
 430          */
 431         public Boolean getBoolean(String key) {
 432                 Attr attr = element.getAttributeNode(key);
 433                 if (attr == null)
 434                         return null;
 435                 String strValue = attr.getValue();
 436                 if ("true".equalsIgnoreCase(strValue))
 437                         return new Boolean(true);
 438                 else
 439                         return new Boolean(false);
 440         }
 441
 442         /*
 443          * @see IMemento#putBoolean(String, boolean)
 444          */
 445         public void putBoolean(String key, boolean value) {
 446                 element.setAttribute(key, value ? "true" : "false");
 447         }
 448 }