1 package org.codehaus.plexus.digest;
2
3 /*
4 * Copyright 2001-2006 The Codehaus.
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * 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, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 import java.io.InputStream;
20
21 /**
22 * Gradually create a digest for a stream.
23 *
24 * @author <a href="mailto:brett@apache.org">Brett Porter</a>
25 */
26 public interface StreamingDigester
27 {
28 String ROLE = StreamingDigester.class.getName();
29
30 /**
31 * Get the algorithm used for the checksum.
32 *
33 * @return the algorithm
34 */
35 String getAlgorithm();
36
37 /**
38 * Reset the hashcode calculation algorithm.
39 * Only useful when performing incremental hashcodes based on repeated use of {@link #update(InputStream)}
40 *
41 * @throws DigesterException if there was a problem with the internal message digest
42 */
43 void reset()
44 throws DigesterException;
45
46 /**
47 * Calculate the current checksum.
48 *
49 * @return the current checksum.
50 * @throws DigesterException if there was a problem computing the hashcode.
51 */
52 String calc()
53 throws DigesterException;
54
55 /**
56 * Update the checksum with the content of the input stream.
57 *
58 * @param is the input stream
59 * @throws DigesterException if there was a problem computing the hashcode.
60 */
61 void update( InputStream is )
62 throws DigesterException;
63
64 }