001    /**
002     * ================================================
003     * LibLoader : a free Java resource loading library
004     * ================================================
005     *
006     * Project Info:  http://reporting.pentaho.org/libloader/
007     *
008     * (C) Copyright 2006, by Pentaho Corporation and Contributors.
009     *
010     * This library is free software; you can redistribute it and/or modify it under the terms
011     * of the GNU Lesser General Public License as published by the Free Software Foundation;
012     * either version 2.1 of the License, or (at your option) any later version.
013     *
014     * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
015     * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
016     * See the GNU Lesser General Public License for more details.
017     *
018     * You should have received a copy of the GNU Lesser General Public License along with this
019     * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
020     * Boston, MA 02111-1307, USA.
021     *
022     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
023     * in the United States and other countries.]
024     *
025     *
026     * ------------
027     * $Id: ResourceData.java 2777 2007-05-04 14:21:56Z taqua $
028     * ------------
029     * (C) Copyright 2006, by Pentaho Corporation.
030     */
031    package org.jfree.resourceloader;
032    
033    import java.io.InputStream;
034    
035    /**
036     * A resource data object encapsulates the raw data of an resource at a given
037     * point in the past.
038     *
039     * Any change to the resource increases the version number. Version numbers
040     * are not needed to be checked regulary, but must be checked on each call to
041     * 'getVersion()'.
042     *
043     * This definitly does *not* solve the problem of concurrent modifications; if
044     * you need to be sure that the resource has not been altered between the last
045     * call to 'getVersion' and 'getResource..' external locking mechanism have to
046     * be implemented.
047     *
048     * @author Thomas Morgner
049     */
050    public interface ResourceData
051    {
052      public static final String CONTENT_LENGTH = "content-length";
053      public static final String CONTENT_TYPE = "content-type";
054      public static final String FILENAME = "filename";
055    
056      public InputStream getResourceAsStream(ResourceManager caller) throws ResourceLoadingException;
057    
058      /**
059       * This is dangerous, especially if the resource is large.
060       *
061       * @param caller
062       * @return
063       * @throws ResourceLoadingException
064       */
065      public byte[] getResource(ResourceManager caller) throws ResourceLoadingException;
066    
067      /**
068       * Tries to read data into the given byte-array.
069       *
070       * @param caller
071       * @param target
072       * @param offset
073       * @param length
074       * @return the number of bytes read or -1 if no more data can be read.
075       * @throws ResourceLoadingException
076       */
077      public int getResource(ResourceManager caller, byte[] target, int offset, int length)
078          throws ResourceLoadingException;
079    
080      public Object getAttribute (String key);
081      public ResourceKey getKey();
082      public long getVersion(ResourceManager caller)
083              throws ResourceLoadingException;
084    
085    }