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jEdit 4.3.1 » org » gjt » sp » util » XMLUtilities.java
/*
 * StandardUtilities.java - Miscelaneous XML utility functions.
 * :tabSize=8:indentSize=8:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 1999, 2006 Marcelo Vanzin, Slava Pestov
 * Portions copyright (C) 2000 Richard S. Hall
 * Portions copyright (C) 2001 Dirk Moebius
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package org.gjt.sp.util;

//{{{ Imports
import java.io.InputStream;
import java.io.BufferedInputStream;
import java.io.IOException;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;
//}}}

/**
 * XML utility methods that only depend on the JDK.
 *
 * @author Marcelo Vanzin
 * @version $Id: XMLUtilities.java 13929 2008-10-25 14:23:41Z k_satoda $
 * @since 4.3pre6
 */
public class XMLUtilities
{

  //{{{ charsToEntities() method
  /**
   * Converts <, >, & in the string to their HTML entity
   * equivalents.
   *
   * <p>If <code>xml11</code> is true, then character entities
   * are used to convert illegal XML characters (mainly ASCII
   * control characters).</p>
   *
   * @param str The string
   * @param xml11 Whether to allow XML 1.1 constructs.
   */
  public static String charsToEntities(String str, boolean xml11)
  {
    StringBuilder buf = new StringBuilder(str.length());
    for(int i = 0; i < str.length(); i++)
    {
      char ch = str.charAt(i);

      // control characters, excluding \t, \r and \n
      // See: http://www.w3.org/International/questions/qa-controls
      if (((0x00 <= ch && ch <= 0x1F) || (0x7F <= ch && ch <= 0x9F))
        && ch != '\r' && ch != '\n' && ch != '\t')
      {
        if (xml11 && ch != 0x00)
        {
          buf.append("&#").append((int)ch).append(';');
        }
        else
        {
          // The character is illegal.
          // But put a PI instead, to make it
          // recoverable in certain apps.
          buf.append("<?illegal-xml-character ")
            .append((int)ch)
            .append("?>");
        }
        continue;
      }

      switch(ch)
      {
      case '<':
        buf.append("&lt;");
        break;
      case '>':
        buf.append("&gt;");
        break;
      case '&':
        buf.append("&amp;");
        break;
      default:
        buf.append(ch);
        break;
      }
    }
    return buf.toString();
  } //}}}

  //{{{ parseXML() method
  /**
   * Convenience method for parsing an XML file. This method will
   * wrap the resource in an InputSource and set the source's
   * systemId to "jedit.jar" (so the source should be able to
   * handle any external entities by itself).
   *
   * <p>SAX Errors are caught and are not propagated to the caller;
   * instead, an error message is printed to jEdit's activity
   * log. So, if you need custom error handling, <b>do not use
   * this method</b>.
   *
   * <p>The given stream is closed before the method returns,
   * regardless whether there were errors or not.</p>
   *
   * @return true if any error occured during parsing, false if success.
   */
  public static boolean parseXML(InputStream in, DefaultHandler handler)
    throws IOException
  {
    try
    {
      XMLReader parser = XMLReaderFactory.createXMLReader();
      InputSource isrc = new InputSource(
        new BufferedInputStream(in));
      isrc.setSystemId("jedit.jar");
      parser.setContentHandler(handler);
      parser.setDTDHandler(handler);
      parser.setEntityResolver(handler);
      parser.setErrorHandler(handler);
      parser.parse(isrc);
    }
    catch(SAXParseException se)
    {
      int line = se.getLineNumber();
      Log.log(Log.ERROR,XMLUtilities.class,
        "while parsing from " + in + ": SAXParseException: line " + line + ": " , se);
      return true;
    }
    catch(SAXException e)
    {
      Log.log(Log.ERROR,XMLUtilities.class,e);
      return true;
    }
    finally
    {
      try
      {
        if(in != null)
          in.close();
      }
      catch(IOException io)
      {
        Log.log(Log.ERROR,XMLUtilities.class,io);
      }
    }
    return false;
  } //}}}

  //{{{ resolveEntity() method
  /**
   * Tries to find the given systemId in the context of the given
   * class. If the given systemId ends with the given test string,
   * then try to load a resource using the Class's
   * <code>getResourceAsStream()</code> method using the test string
   * as the resource.
   *
   * <p>This is used a lot internally while parsing XML files used
   * by jEdit, but anyone is free to use the method if it sounds
   * usable.</p>
   */
  public static InputSource findEntity(String systemId, String test, Class where)
  {
    if (systemId != null && systemId.endsWith(test))
    {
      try
      {
        return new InputSource(new BufferedInputStream(
          where.getResourceAsStream(test)));
      }
      catch (Exception e)
      {
        Log.log(Log.ERROR,XMLUtilities.class,
          "Error while opening " + test + ':');
        Log.log(Log.ERROR,XMLUtilities.class,e);
      }
    }

    return null;
  } //}}}

  private XMLUtilities() { }
}

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