Source code

001/**
002 * Copyright 2010-2013 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.common.util;
017
018import java.io.UnsupportedEncodingException;
019import java.util.List;
020
021import org.apache.commons.lang3.StringUtils;
022
023/**
024 * Operations on <code>String</code> that are <code>null</code> safe
025 */
026public class Str {
027
028        public static final String EMPTY_STRING = "";
029        public static final String UTF8 = Encodings.UTF8;
030        public static final String COMMA = ",";
031        public static final String SPACE = " ";
032        public static final String CR = "\r";
033        public static final String LF = "\n";
034        public static final String DOT = ".";
035        public static final String COLON = ":";
036        public static final String FORWARD_SLASH = "/";
037        public static final char DOUBLE_QUOTE = '"';
038        public static final String CDATA_PREFIX = "<![CDATA[";
039        public static final String CDATA_SUFFIX = "]]>";
040        public static final String[] EMPTY_ARRAY = new String[0];
041
042        private static final String CONCEALED_PREFIX = "cnc--";
043
044        /**
045         * <p>
046         * A trivial way to conceal <code>text</code>. Can be reversed using <code>reveal()</code>. Do <b>NOT</b> use this method in an attempt to obscure sensitive data. The algorithm
047         * is completely trivial and exceedingly simple to reverse engineer. Not to mention, the <code>reveal()</code> method can reproduce the original string without requiring any
048         * secret knowledge.
049         * </p>
050         * 
051         * <p>
052         * The use case here is to help prevent someone with otherwise mostly good intentions from altering a piece of information in a way they should not. This is <b>NOT</b> intended
053         * to defeat any serious attempt at discovering the original text.
054         * </p>
055         * 
056         * <p>
057         * Think a hungry sales or marketing rep who stumbles across a config file with the entry <code>vending.machine.refill.day=wed</code> in it and tries to change that to
058         * <code>mon</code> in order to beat a case of the munchies. :)
059         * </p>
060         * 
061         * <p>
062         * If the entry says <code>vending.machine.refill.day=cnc--jrq</code> instead of <code>vending.machine.refill.day=wed</code> they are far more likely to ask around before they
063         * change it <b>OR</b> just give up and head out to lunch instead.
064         * </p>
065         * 
066         * @see reveal
067         */
068        public static final String conceal(String text) {
069                if (text == null) {
070                        return null;
071                }
072                Assert.noBlanks(text);
073                if (isConcealed(text)) {
074                        return text;
075                }
076                Assert.notConcealed(text);
077                char[] chars = text.toCharArray();
078                StringBuilder sb = new StringBuilder();
079                sb.append(CONCEALED_PREFIX);
080                for (char c : chars) {
081                        sb.append(Ascii.flip(c));
082                }
083                return sb.toString();
084        }
085
086        /**
087         * Reveal the original contents of a string concealed by the <code>conceal</code> method.
088         * 
089         * @see conceal
090         */
091        public static final String reveal(String text) {
092                if (text == null) {
093                        return null;
094                }
095                Assert.noBlanks(text);
096                if (!isConcealed(text)) {
097                        return text;
098                }
099                Assert.concealed(text);
100                String substring = removePrefix(text, CONCEALED_PREFIX);
101                char[] chars = substring.toCharArray();
102                StringBuilder sb = new StringBuilder();
103                for (char c : chars) {
104                        sb.append(Ascii.flip(c));
105                }
106                return sb.toString();
107        }
108
109        /**
110         * Return true if <code>text</code> is concealed
111         */
112        public static final boolean isConcealed(String text) {
113                return StringUtils.startsWith(text, CONCEALED_PREFIX);
114        }
115
116        /**
117         * If <code>strings</code> are <code>null</code> return <code>EMPTY_ARRAY</code>, otherwise return <code>strings</code>.
118         */
119        public static final String[] toEmptyArray(String[] strings) {
120                if (strings == null) {
121                        return EMPTY_ARRAY;
122                } else {
123                        return strings;
124                }
125        }
126
127        /**
128         * Convert the tokens into a string delimited by the colon "<code>:</code>" character
129         * 
130         * <pre>
131         *   "foo","bar" ,"baz"  -> foo:bar:baz
132         *   "foo", null ,"baz"  -> foo::baz
133         *   "foo", ""   ,"baz"  -> foo::baz
134         *   "foo", null , null  -> foo::
135         *    null,"bar" , null  -> :bar:
136         * </pre>
137         */
138        public static final String getId(String... tokens) {
139                if (tokens == null) {
140                        return null;
141                }
142                StringBuilder sb = new StringBuilder();
143                for (int i = 0; i < tokens.length; i++) {
144                        if (i != 0) {
145                                sb.append(COLON);
146                        }
147                        sb.append(StringUtils.trimToEmpty(tokens[i]));
148                }
149                return sb.toString();
150        }
151
152        /**
153         * Turn the string into CDATA - http://en.wikipedia.org/wiki/CDATA
154         */
155        public static final String cdata(String s) {
156                if (s == null) {
157                        return null;
158                } else {
159                        return CDATA_PREFIX + s + CDATA_SUFFIX;
160                }
161        }
162
163        /**
164         * If <code>s</code> ends with <code>suffix</code>, remove it
165         */
166        public static final String removeSuffix(String s, String suffix) {
167                if (StringUtils.endsWith(s, suffix)) {
168                        int end = StringUtils.length(s) - StringUtils.length(suffix);
169                        return StringUtils.substring(s, 0, end);
170                } else {
171                        return s;
172                }
173        }
174
175        /**
176         * If <code>s</code> starts with <code>prefix</code>, remove it
177         */
178        public static final String removePrefix(String s, String prefix) {
179                if (StringUtils.startsWith(s, prefix)) {
180                        int beginIndex = StringUtils.length(prefix);
181                        return StringUtils.substring(s, beginIndex);
182                } else {
183                        return s;
184                }
185        }
186
187        /**
188         * Return true if <code>s</code> starts with <code>prefix</code> and ends with <code>suffix</code>
189         */
190        public static final boolean matches(String s, String prefix, String suffix) {
191                return StringUtils.startsWith(s, prefix) && StringUtils.endsWith(s, suffix);
192        }
193
194        public static final String remove(String s, String prefix, String suffix) {
195                String returnValue = s;
196                returnValue = removePrefix(returnValue, prefix);
197                returnValue = removeSuffix(returnValue, suffix);
198                return returnValue;
199        }
200
201        /**
202         * If s is null return "" otherwise return s
203         */
204        public static final String toEmpty(String s) {
205                if (s == null) {
206                        return "";
207                } else {
208                        return s;
209                }
210        }
211
212        public static final String getString(byte[] bytes, String encoding) {
213                if (bytes == null) {
214                        return null;
215                }
216                if (encoding == null) {
217                        return new String(bytes);
218                }
219                try {
220                        return new String(bytes, encoding);
221                } catch (UnsupportedEncodingException e) {
222                        throw new IllegalArgumentException(e);
223                }
224        }
225
226        public static final byte[] getUTF8Bytes(String s) {
227                if (s == null) {
228                        return null;
229                } else {
230                        return getBytes(s, UTF8);
231                }
232        }
233
234        public static final byte[] getBytes(String s, String encoding) {
235                if (s == null) {
236                        return null;
237                }
238                if (encoding == null) {
239                        return s.getBytes();
240                }
241                try {
242                        return s.getBytes(encoding);
243                } catch (UnsupportedEncodingException e) {
244                        throw new IllegalArgumentException(e);
245                }
246        }
247
248        public static final boolean contains(List<String> tokens, String value, boolean caseSensitive) {
249                for (String token : tokens) {
250                        if (equals(token, value, caseSensitive)) {
251                                return true;
252                        }
253                }
254                return false;
255        }
256
257        public static final boolean equals(String s1, String s2, boolean caseSensitive) {
258                if (caseSensitive) {
259                        return StringUtils.equals(s1, s2);
260                } else {
261                        return StringUtils.equalsIgnoreCase(s1, s2);
262                }
263        }
264
265        /**
266         * Combine <code>tokens</code> into a <code>String</code>
267         */
268        public static final String toString(String[] tokens) {
269                if (tokens == null) {
270                        return null;
271                }
272                StringBuilder sb = new StringBuilder();
273                for (String token : tokens) {
274                        sb.append(token);
275                }
276                return sb.toString();
277        }
278
279        /**
280         * Convert dots to forward slashes and trim.
281         */
282        public static final String getPath(String s) {
283                return StringUtils.trim(StringUtils.replace(s, DOT, FORWARD_SLASH));
284        }
285
286        /**
287         * Surround the string with double quotes.
288         */
289        public static final String quote(String s) {
290                return s == null ? null : DOUBLE_QUOTE + s + DOUBLE_QUOTE;
291        }
292
293        /**
294         * Split comma separated values into tokens, optionally trimming the tokens.
295         */
296        public static final String[] splitCSV(String csv, boolean trim) {
297                return split(csv, COMMA, trim);
298        }
299
300        /**
301         * Split comma separated values into tokens, trimming as we go.
302         */
303        public static final String[] splitAndTrimCSV(String csv) {
304                return splitCSV(csv, true);
305        }
306
307        /**
308         * Split the string into tokens using the indicated separator, trimming as we go.
309         */
310        public static final String[] splitAndTrim(String s, String separatorChars) {
311                return split(s, separatorChars, true);
312        }
313
314        /**
315         * Split the string into tokens using the indicated separator chars, optionally trimming the tokens.
316         */
317        public static final String[] split(String s, String separatorChars, boolean trim) {
318                String[] tokens = StringUtils.split(s, separatorChars);
319                if (tokens == null) {
320                        return null;
321                }
322                for (int i = 0; i < tokens.length; i++) {
323                        tokens[i] = trim ? StringUtils.trim(tokens[i]) : tokens[i];
324                }
325                return tokens;
326        }
327
328        /**
329         * Replace carriage returns and linefeeds with a space
330         */
331        public static final String flatten(String s) {
332                return flatten(s, SPACE, SPACE);
333        }
334
335        /**
336         * Replace carriage returns with <code>cr</code> and linefeeds with <code>lf</code>.
337         */
338        public static final String flatten(String s, String cr, String lf) {
339                return StringUtils.replace(StringUtils.replace(s, CR, cr), LF, lf);
340        }
341
342        /**
343         * Replace <code>cr</code> with carriage return and <code>lf</code> with linefeed.
344         */
345        public static final String inflate(String s, String cr, String lf) {
346                return StringUtils.replace(StringUtils.replace(s, cr, CR), lf, LF);
347        }
348}