1 /*
2 * Copyright 2009 Red Hat, Inc.
3 *
4 * Red Hat licenses this file to you under the Apache License, version 2.0
5 * (the "License"); you may not use this file except in compliance with the
6 * License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package org.jboss.netty.util.internal;
17
18 import java.util.Formatter;
19
20 /**
21 * String utility class.
22 *
23 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
24 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
25 * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
26 */
27 public class StringUtil {
28
29 private StringUtil() {
30 // Unused.
31 }
32
33 public static final String NEWLINE;
34
35 static {
36 String newLine = null;
37
38 try {
39 newLine = new Formatter().format("%n").toString();
40 } catch (Exception e) {
41 newLine = "\n";
42 }
43
44 NEWLINE = newLine;
45 }
46
47 /**
48 * Strip an Object of it's ISO control characters.
49 *
50 * @param value
51 * The Object that should be stripped. This objects toString method will
52 * called and the result passed to {@link #stripControlCharacters(String)}.
53 * @return {@code String}
54 * A new String instance with its hexadecimal control characters replaced
55 * by a space. Or the unmodified String if it does not contain any ISO
56 * control characters.
57 */
58 public static String stripControlCharacters(Object value) {
59 if (value == null) {
60 return null;
61 }
62
63 return stripControlCharacters(value.toString());
64 }
65
66 /**
67 * Strip a String of it's ISO control characters.
68 *
69 * @param value
70 * The String that should be stripped.
71 * @return {@code String}
72 * A new String instance with its hexadecimal control characters replaced
73 * by a space. Or the unmodified String if it does not contain any ISO
74 * control characters.
75 */
76 public static String stripControlCharacters(String value) {
77 if (value == null) {
78 return null;
79 }
80
81 boolean hasControlChars = false;
82 for (int i = value.length() - 1; i >= 0; i --) {
83 if (Character.isISOControl(value.charAt(i))) {
84 hasControlChars = true;
85 break;
86 }
87 }
88
89 if (!hasControlChars) {
90 return value;
91 }
92
93 StringBuilder buf = new StringBuilder(value.length());
94 int i = 0;
95
96 // Skip initial control characters (i.e. left trim)
97 for (; i < value.length(); i ++) {
98 if (!Character.isISOControl(value.charAt(i))) {
99 break;
100 }
101 }
102
103 // Copy non control characters and substitute control characters with
104 // a space. The last control characters are trimmed.
105 boolean suppressingControlChars = false;
106 for (; i < value.length(); i ++) {
107 if (Character.isISOControl(value.charAt(i))) {
108 suppressingControlChars = true;
109 continue;
110 } else {
111 if (suppressingControlChars) {
112 suppressingControlChars = false;
113 buf.append(' ');
114 }
115 buf.append(value.charAt(i));
116 }
117 }
118
119 return buf.toString();
120 }
121 }