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 * https://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>
26 * This class is immutable and thread-safe.
27 * </p>
28 *
29 * @since 1.4
30 */
31 final class Utils {
32
33 /**
34 * Radix used in encoding and decoding.
35 */
36 private static final int RADIX = 16;
37
38 static final byte SPACE = 32;
39
40 /**
41 * Returns the numeric value of the character {@code b} in radix 16.
42 *
43 * @param b The byte to be converted.
44 * @return The numeric value represented by the character in radix 16.
45 * @throws DecoderException 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 hexadecimal digit of the lower 4 bits of the int.
57 *
58 * @param b The input int.
59 * @return The upper case hexadecimal digit of the lower 4 bits of the int.
60 */
61 static char hexChar(final int b) {
62 return Character.toUpperCase(Character.forDigit(b & 0xF, RADIX));
63 }
64 }