Resolve a relative URL string against an absolute URL string : URL « Network Protocol « Java






Resolve a relative URL string against an absolute URL string

    
/*
Copyright (c) 2003 eInnovation Inc. All rights reserved

This library is free software; you can redistribute it and/or modify it under the terms
of the GNU Lesser General Public License as published by the Free Software Foundation;
either version 2.1 of the License, or (at your option) any later version.

This library 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 Lesser General Public License for more details.
*/

/*--

 Copyright (C) 2001-2002 Anthony Eden.
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:

 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions, and the following disclaimer.

 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions, and the disclaimer that follows
    these conditions in the documentation and/or other materials
    provided with the distribution.

 3. The name "JPublish" must not be used to endorse or promote products
    derived from this software without prior written permission.  For
    written permission, please contact me@anthonyeden.com.

 4. Products derived from this software may not be called "JPublish", nor
    may "JPublish" appear in their name, without prior written permission
    from Anthony Eden (me@anthonyeden.com).

 In addition, I request (but do not require) that you include in the
 end-user documentation provided with the redistribution and/or in the
 software itself an acknowledgement equivalent to the following:
     "This product includes software developed by
      Anthony Eden (http://www.anthonyeden.com/)."

 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 */


/**
 * Utility class for working with request paths.
 *
 * @author Anthony Eden
 */
public final class PathUtilities
{
  private static final String WILDCARD = "*";


  /**
   * resolve a relative URL string against an absolute URL string.
   *
   * This method was adapted from the CalCom library at http://www.calcom.de
   *
   * <p>the absolute URL string is the start point for the
   * relative path.</p>
   *
   * <p><b>Example:</b></p>
   * <pre>
   *   relative path:  ../images/test.jpg
   *   absolute path:  file:/d:/eigene dateien/eigene bilder/
   *   result:         file:/d:/eigene dateien/images/test.jpg
   * </pre>
   *
   * @param relPath  The relative URL string to resolve.  Unlike the Calcom version, this may be
   *           an absolute path, if it starts with "/".
   * @param absPath  The absolute URL string to start at.  Unlike the CalCom version, this may be a filename
   *           rather than just a path.
   *
   * @return the absolute URL string resulting from resolving relPath against absPath
   * 
   * @author Ulrich Hilger
   * @author CalCom
   * @author <a href="http://www.calcom.de">http://www.calcom.de</a>
   * @author <a href="mailto:info@calcom.de">info@calcom.de</a>
   * @author Dennis Brown (eInnovation)
   */
  public static String resolveRelativePath(String relPath, String absPath)
  {
    //  if relative path is really absolute, then ignore absPath (eInnovation change)
    if ( relPath.startsWith( "/" ) )
    {
      absPath = "";
    }

    String newAbsPath = absPath;
    String newRelPath = relPath;
    if( relPath.startsWith("$"))
    {
      return relPath;
    }
    else if (absPath.endsWith("/"))
    {
      newAbsPath = absPath.substring(0, absPath.length() - 1);
    }
    else
    {
      //  absPath ends with a filename, remove it (eInnovation change)
      int lastSlashIndex = absPath.lastIndexOf('/');
      if ( lastSlashIndex >= 0 )
      {
        newAbsPath = absPath.substring( 0, lastSlashIndex );
      }
      else
      {
        newAbsPath = "";
      }
    }

    int relPos = newRelPath.indexOf("../");
    while (relPos > -1)
    {
      newRelPath = newRelPath.substring(relPos + 3);
      int lastSlashInAbsPath = newAbsPath.lastIndexOf( "/" );
      if ( lastSlashInAbsPath >= 0 )
      {
        newAbsPath = newAbsPath.substring(0, newAbsPath.lastIndexOf("/"));
      }
      else
      {
        //  eInnovation change: fix potential exception
        newAbsPath = "";
      }
      relPos = newRelPath.indexOf("../");
    }
    String returnedPath;
    if (newRelPath.startsWith("/"))
    {
      returnedPath = newAbsPath + newRelPath;
    }
    else
    {
      returnedPath = newAbsPath + "/" + newRelPath;
    }


    //  remove any "." references to current directory (eInnovation change)
    //  For example:
    //    "./junk" becomes "junk"
    //    "/./junk" becomes "/junk"
    //    "junk/." becomes "junk"
    while ( returnedPath.endsWith( "/." ) )
    {
      returnedPath = returnedPath.substring( 0, returnedPath.length() - 2 );
    }
    do
    {
      int dotSlashIndex = returnedPath.lastIndexOf( "./" );
      if ( dotSlashIndex < 0 )
      {
        break;
      }
      else if ( dotSlashIndex == 0 || returnedPath.charAt( dotSlashIndex - 1 ) != '.' )
      {
        String firstSubstring;
        if ( dotSlashIndex > 0 )
        {
          firstSubstring = returnedPath.substring( 0, dotSlashIndex );
        }
        else
        {
          firstSubstring = "";
        }
        String secondSubstring;
        if ( dotSlashIndex + 2 < returnedPath.length() )
        {
          secondSubstring = returnedPath.substring( dotSlashIndex + 2, returnedPath.length() );
        }
        else
        {
          secondSubstring = "";
        }
        returnedPath = firstSubstring + secondSubstring;
      }
    } while ( true );

    return returnedPath;
  }

}

   
    
    
    
  








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