CheckedReadOnlySfxDriver


1   /*
2    * CheckedReadOnlySfxDriver.java
3    *
4    * Created on 30. Juni 2006, 00:06
5    */
6   /*
7    * Copyright 2006 Schlichtherle IT Services
8    *
9    * Licensed under the Apache License, Version 2.0 (the "License");
10   * you may not use this file except in compliance with the License.
11   * You may obtain a copy of the License at
12   *
13   *     http://www.apache.org/licenses/LICENSE-2.0
14   *
15   * Unless required by applicable law or agreed to in writing, software
16   * distributed under the License is distributed on an "AS IS" BASIS,
17   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18   * See the License for the specific language governing permissions and
19   * limitations under the License.
20   */
21  
22  package de.schlichtherle.io.archive.zip;
23  
24  import de.schlichtherle.io.rof.*;
25  
26  import java.io.*;
27  import java.util.zip.*;
28  
29  /**
30   * A {@link ReadOnlySfxDriver} which checks the CRC-32 value for all ZIP
31   * entries in input archives.
32   * The additional CRC-32 computation makes this class slower than its super
33   * class.
34   * <p>
35   * If there is a mismatch of the CRC-32 values for a ZIP entry in an input
36   * archive, the {@link InputStream#close} method of the corresponding stream
37   * for the archive entry will throw a
38   * {@link de.schlichtherle.util.zip.CRC32Exception}.
39   * This exception is then propagated through the stack up to the corresponding
40   * file operation in the package <code>de.schlichtherle.io</code> where it is
41   * either allowed to pass on or is catched and processed accordingly.
42   * For example, the {@link de.schlichtherle.io.FileInputStream#close()}
43   * method would allow the <code>CRC32Exception</code> to pass on to the
44   * client application, whereas the
45   * {@link de.schlichtherle.io.File#catTo(OutputStream)} method would simply
46   * return <code>false</code>.
47   * Other than this, the archive entry will be processed normally.
48   * So if just the CRC-32 value for the entry in the archive file has been
49   * modified, you can still read its entire contents.
50   * <p>
51   * Instances of this class are immutable.
52   * 
53   * @see ReadOnlySfxDriver
54   * @see CheckedZip32InputArchive
55   * @see CheckedZip32OutputArchive
56   * 
57   * @author Christian Schlichtherle
58   * @version @version@
59   * @since TrueZIP 6.1
60   */
61  public class CheckedReadOnlySfxDriver extends ReadOnlySfxDriver {
62  
63      /**
64       * Equivalent to {@link #CheckedReadOnlySfxDriver(String)
65       * CheckedReadOnlySfxDriver(ENCODING)}.
66       * This parameter is based on heuristics.
67       */
68      public CheckedReadOnlySfxDriver() {
69          this(ENCODING);
70      }
71  
72      /**
73       * Equivalent to
74       * {@link ReadOnlySfxDriver#ReadOnlySfxDriver(String)
75       * super(encoding)}.
76       * This parameter is based on heuristics.
77       */
78      public CheckedReadOnlySfxDriver(String   encoding) {
79          super(encoding);
80      }
81      
82      protected Zip32InputArchive createZip32InputArchive(
83              ReadOnlyFile rof,
84              String   encoding,
85              boolean preambled,
86              boolean postambled)
87      throws  NullPointerException  ,
88              UnsupportedEncodingException,
89              FileNotFoundException,
90              ZipException,
91              IOException {
92          return new CheckedZip32InputArchive(rof, encoding, preambled, postambled);
93      }
94  }
95
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