1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.codec.net;
19
20 import org.apache.commons.codec.DecoderException;
21
22 /**
23 * Utility methods for this package.
24 *
25 * <p>This class is immutable and thread-safe.</p>
26 *
27 * @version $Id: Utils.java 1811344 2017-10-06 15:19:57Z ggregory $
28 * @since 1.4
29 */
30 class Utils {
31
32 /**
33 * Radix used in encoding and decoding.
34 */
35 private static final int RADIX = 16;
36
37 /**
38 * Returns the numeric value of the character <code>b</code> in radix 16.
39 *
40 * @param b
41 * The byte to be converted.
42 * @return The numeric value represented by the character in radix 16.
43 *
44 * @throws DecoderException
45 * Thrown when the byte is not valid per {@link Character#digit(char,int)}
46 */
47 static int digit16(final byte b) throws DecoderException {
48 final int i = Character.digit((char) b, RADIX);
49 if (i == -1) {
50 throw new DecoderException("Invalid URL encoding: not a valid digit (radix " + RADIX + "): " + b);
51 }
52 return i;
53 }
54
55 /**
56 * Returns the upper case hex digit of the lower 4 bits of the int.
57 *
58 * @param b the input int
59 * @return the upper case hex digit of the lower 4 bits of the int.
60 */
61 static char hexDigit(final int b) {
62 return Character.toUpperCase(Character.forDigit(b & 0xF, RADIX));
63 }
64
65 }