AttachmentStorage


1   /*
2    * This file is part of "SnipSnap Wiki/Weblog".
3    *
4    * Copyright (c) 2002 Stephan J. Schmidt, Matthias L. Jugel
5    * All Rights Reserved.
6    *
7    * Please visit http://snipsnap.org/ for updates and contact.
8    *
9    * --LICENSE NOTICE--
10   * This program is free software; you can redistribute it and/or
11   * modify it under the terms of the GNU General Public License
12   * as published by the Free Software Foundation; either version 2
13   * of the License, or (at your option) any later version.
14   *
15   * This program is distributed in the hope that it will be useful,
16   * but WITHOUT ANY WARRANTY; without even the implied warranty of
17   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18   * GNU General Public License for more details.
19   *
20   * You should have received a copy of the GNU General Public License
21   * along with this program; if not, write to the Free Software
22   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23   * --LICENSE NOTICE--
24   */
25  
26  package org.snipsnap.snip.attachment.storage;
27  
28  import org.snipsnap.snip.attachment.Attachment;
29  
30  import java.io.InputStream  ;
31  import java.io.OutputStream  ;
32  import java.io.IOException  ;
33  
34  /**
35   * Interface that describes backends for attachment storage
36   *
37   * @author Stephan J. Schmidt
38   * @version $Id: AttachmentStorage.java 1693 2004-06-27 10:59:44Z leo $
39   */
40  
41  public interface AttachmentStorage {
42    /**
43     * Check if the attachment actually exists.
44     * @param attachment the attachment to check
45     * @return true for existing data or false if missing
46     */
47    public boolean exists(Attachment attachment);
48    /**
49     * Get the output stream for this attachment to store its data in.
50     * @param attachment the attachment meta data
51     * @return an output stream where the data can be written to
52     * @throws IOException if the attachment cannot be stored
53     */
54    public OutputStream   getOutputStream(Attachment attachment) throws IOException  ;
55    /**
56     * Get an input stream to read the attachment data.
57     * @param attachment the attachment meta data
58     * @return the input stream to read from
59     * @throws IOException if the attachment cannot be read
60     */
61    public InputStream   getInputStream(Attachment attachment) throws IOException  ;
62    /**
63     * Delete the attachment
64     * @param attachment the attachment meta data
65     * @throws IOException if the data cannot be deleted
66     */
67    public void delete(Attachment attachment) throws IOException  ;
68    /**
69     * Verify the meta data of the attachment. An implementation should check
70     * all available information about the attachment, like size, modification
71     * time and if possible the file type. If there are differences the metda data
72     * will be modified and the method returns false.
73     *
74     * @param attachment the attachment meta data
75     * @return true if the meta data is correct, false if the attachment meta data was modified
76     * @throws IOException if the attachment is missing or not verifyable
77     *
78     */
79    public boolean verify(Attachment attachment) throws IOException  ;
80  }
81
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