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 }