HistoryIO.java

package org.waarp.xample;

/*
 * Copyright (c) 2003 Felix Golubov
 */

import java.util.*;
import java.io.*;
import org.w3c.dom.*;
import org.apache.xerces.parsers.DOMParser;
import org.apache.xerces.dom.DocumentImpl;
import org.apache.xml.serialize.OutputFormat;
import org.apache.xml.serialize.XMLSerializer;

/**
 * A helper class for the XAmple application which reads and writes history
 * of accessed XSD and XML files. The history is stored in the XML format.
 *
 * @author Felix Golubov
 * @version 2.0
 */

public class HistoryIO
{
  public static final String HISTORY_FILE_NAME = "history.xml";
  public static final String HISTORY = "history";
  public static final String XSD_DOC = "xsd-doc";
  public static final String XML_DOC = "xml-doc";
  public static final String FILE = "file";

  static void populateHistory(History history, Element element)
  {
    NodeList lst = element.getChildNodes();
    history.items = new ArrayList();
    for (int i = lst.getLength() - 1; i >= 0; i--)
    {
      if (!(lst.item(i) instanceof Element))
        continue;
      Element child = (Element)lst.item(i);
      String path = child.getAttribute(FILE);
      if (path != null && path.length() > 0)
      {
        History childHistory = history.put(path);
        populateHistory(childHistory, child);
      }
    }
  }

  public static void load(History history)
  {
    File file = new File(HISTORY_FILE_NAME);
    if (!file.exists())
      return;
    Element root = null;
    try {
      DOMParser parser = new DOMParser();
      parser.parse(file.toURI().toURL().toString());
      Document doc = parser.getDocument();
      root = doc.getDocumentElement();
      populateHistory(history, root);
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }

  public static void save(History history)
  {
    Document doc = new DocumentImpl();
    Element root = doc.createElement(HISTORY);
    doc.appendChild(root);
    if (history.items != null)
    {
      for (int i = 0; i < history.items.size(); i++)
      {
        History hXSD = (History)history.items.get(i);
        Element eXSD = doc.createElement(XSD_DOC);
        eXSD.setAttribute(FILE, hXSD.path);
        root.appendChild(eXSD);
        if (hXSD.items == null)
          continue;
        for (int j = 0; j < hXSD.items.size(); j++)
        {
          History hXML = (History)hXSD.items.get(j);
          Element eXML = doc.createElement(XML_DOC);
          eXML.setAttribute(FILE, hXML.path);
          eXSD.appendChild(eXML);
        }
      }
    }
    File file = new File(HISTORY_FILE_NAME);
    FileOutputStream out = null;
    try {
      file.createNewFile();
      out = new FileOutputStream(file);
      OutputFormat format = new OutputFormat(doc, "UTF-8", true);
      Writer writer = new OutputStreamWriter(out);
      XMLSerializer serial = new XMLSerializer(writer, format);
      serial.asDOMSerializer();
      serial.serialize(doc);
    } catch (Exception ex) {
    } finally {
      try { out.close(); } catch (Exception ignore) {}
    }
  }

}