1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27
28 package org.apache.hc.core5.util;
29
30 import java.util.Locale;
31
32 import org.apache.hc.core5.annotation.Internal;
33
34 /**
35 * @since 4.3
36 */
37 public final class TextUtils {
38
39 private TextUtils() {
40 // Do not allow utility class to be instantiated.
41 }
42
43 /**
44 * Returns true if the parameter is null or of zero length
45 */
46 public static boolean isEmpty(final CharSequence s) {
47 return length(s) == 0;
48 }
49
50 /**
51 * <p>Checks if a CharSequence is empty (""), null or whitespace only.</p>
52 *
53 * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
54 *
55 * <pre>
56 * TextUtils.isBlank(null) = true
57 * TextUtils.isBlank("") = true
58 * TextUtils.isBlank(" ") = true
59 * TextUtils.isBlank("abg") = false
60 * TextUtils.isBlank(" abg ") = false
61 * </pre>
62 *
63 * @param s the CharSequence to check, may be null
64 * @return {@code true} if the CharSequence is null, empty or whitespace only
65 */
66 public static boolean isBlank(final CharSequence s) {
67 final int strLen = length(s);
68 if (strLen == 0) {
69 return true;
70 }
71 for (int i = 0; i < strLen; i++) {
72 if (!Character.isWhitespace(s.charAt(i))) {
73 return false;
74 }
75 }
76 return true;
77 }
78
79 /**
80 * Gets a CharSequence length or {@code 0} if the CharSequence is
81 * {@code null}.
82 *
83 * @param cs
84 * a CharSequence or {@code null}
85 * @return CharSequence length or {@code 0} if the CharSequence is
86 * {@code null}.
87 * @since 5.1
88 */
89 public static int length(final CharSequence cs) {
90 return cs == null ? 0 : cs.length();
91 }
92
93 /**
94 * @since 4.4
95 */
96 public static boolean containsBlanks(final CharSequence s) {
97 final int strLen = length(s);
98 if (strLen == 0) {
99 return false;
100 }
101 for (int i = 0; i < s.length(); i++) {
102 if (Character.isWhitespace(s.charAt(i))) {
103 return true;
104 }
105 }
106 return false;
107 }
108
109 /**
110 * Returns a hexadecimal string with lowercase letters, representing the
111 * values of the {@code bytes}.
112 *
113 * @param bytes whose hex string should be created
114 * @return hex string for the bytes
115 *
116 * @since 5.0
117 */
118 public static String toHexString(final byte[] bytes) {
119 if (bytes == null) {
120 return null;
121 }
122 final StringBuilder buffer = new StringBuilder();
123 for (int i = 0; i < bytes.length; i++) {
124 final int unsignedB = bytes[i] & 0xff;
125 if (unsignedB < 16) {
126 buffer.append('0');
127 }
128 buffer.append(Integer.toHexString(unsignedB));
129 }
130 return buffer.toString();
131 }
132
133 /**
134 * Returns lower case representation of the given string
135 * using {@link Locale#ROOT}.
136 *
137 * @since 5.2
138 */
139 public static String toLowerCase(final String s) {
140 if (s == null) {
141 return null;
142 }
143 return s.toLowerCase(Locale.ROOT);
144 }
145
146 /**
147 * Casts character to byte filtering non-visible and non-ASCII characters
148 * before conversion
149 *
150 * @since 5.2
151 */
152 @Internal
153 public static byte castAsByte(final int c) {
154 if ((c >= 0x20 && c <= 0x7E) || // Visible ASCII
155 (c >= 0xA0 && c <= 0xFF) || // Visible ISO-8859-1
156 c == 0x09) { // TAB
157 return (byte) c;
158 } else {
159 return '?';
160 }
161 }
162
163 }