1 package org.eclipse.aether.util;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.nio.charset.StandardCharsets;
23 import java.security.MessageDigest;
24 import java.security.NoSuchAlgorithmException;
25
26 /**
27 * A simple digester utility for Strings. Uses {@link MessageDigest} for requested algorithm. Supports one-pass or
28 * several rounds of updates, and as result emits hex encoded String.
29 *
30 * @since 1.9.0
31 */
32 public final class StringDigestUtil
33 {
34 private final MessageDigest digest;
35
36 /**
37 * Constructs instance with given algorithm.
38 *
39 * @see #sha1()
40 * @see #sha1(String)
41 */
42 public StringDigestUtil( final String alg )
43 {
44 try
45 {
46 this.digest = MessageDigest.getInstance( alg );
47 }
48 catch ( NoSuchAlgorithmException e )
49 {
50 throw new IllegalStateException( "Not supported digest algorithm: " + alg );
51 }
52 }
53
54 /**
55 * Updates instance with passed in string.
56 */
57 public StringDigestUtil update( String data )
58 {
59 if ( data != null && !data.isEmpty() )
60 {
61 digest.update( data.getBytes( StandardCharsets.UTF_8 ) );
62 }
63 return this;
64 }
65
66 /**
67 * Returns the digest of all strings passed via {@link #update(String)} as hex string. There is no state preserved
68 * and due implementation of {@link MessageDigest#digest()}, same applies here: this instance "resets" itself.
69 * Hence, the digest hex encoded string is returned only once.
70 *
71 * @see MessageDigest#digest()
72 */
73 public String digest()
74 {
75 return ChecksumUtils.toHexString( digest.digest() );
76 }
77
78 /**
79 * Helper method to create {@link StringDigestUtil} using SHA-1 digest algorithm.
80 */
81 public static StringDigestUtil sha1()
82 {
83 return new StringDigestUtil( "SHA-1" );
84 }
85
86 /**
87 * Helper method to calculate SHA-1 digest and hex encode it.
88 */
89 public static String sha1( final String string )
90 {
91 return sha1().update( string ).digest();
92 }
93 }