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1   /****************************************************************
2    * Licensed to the Apache Software Foundation (ASF) under one   *
3    * or more contributor license agreements.  See the NOTICE file *
4    * distributed with this work for additional information        *
5    * regarding copyright ownership.  The ASF licenses this file   *
6    * to you under the Apache License, Version 2.0 (the            *
7    * "License"); you may not use this file except in compliance   *
8    * with the License.  You may obtain a copy of the License at   *
9    *                                                              *
10   *   http://www.apache.org/licenses/LICENSE-2.0                 *
11   *                                                              *
12   * Unless required by applicable law or agreed to in writing,   *
13   * software distributed under the License is distributed on an  *
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
15   * KIND, either express or implied.  See the License for the    *
16   * specific language governing permissions and limitations      *
17   * under the License.                                           *
18   ****************************************************************/
19  
20  package org.apache.james.jdkim.canon;
21  
22  import java.io.FilterOutputStream;
23  import java.io.IOException;
24  import java.io.OutputStream;
25  import java.security.MessageDigest;
26  
27  /**
28   * DigestOutputStream is used as a filter stream or as the ending stream in
29   * order to calculate a digest of a stream.
30   */
31  public class DigestOutputStream extends FilterOutputStream {
32  
33      private MessageDigest md;
34  
35      public DigestOutputStream(MessageDigest md) {
36          this(md, null);
37      }
38  
39      public DigestOutputStream(MessageDigest md, OutputStream out) {
40          super(out);
41          this.md = md;
42      }
43  
44      public void write(int arg0) throws IOException {
45          md.update((byte) arg0);
46          if (out != null)
47              out.write(arg0);
48      }
49  
50      public void write(byte[] b, int off, int len) throws IOException {
51          md.update(b, off, len);
52          if (out != null)
53              out.write(b, off, len);
54      }
55  
56      public void close() throws IOException {
57          if (out != null)
58              super.close();
59      }
60  
61      public void flush() throws IOException {
62          if (out != null)
63              super.flush();
64      }
65  
66      public void write(byte[] b) throws IOException {
67          md.update(b);
68          if (out != null)
69              out.write(b);
70      }
71  
72      /**
73       * @return the stream digest as a byte array
74       */
75      public byte[] getDigest() {
76          return md.digest();
77      }
78  
79  }