| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.lang; |
| |
| import java.util.Random; |
| |
| /** |
| * <p>Operations for random {@code String}s.</p> |
| * <p>Currently <em>private high surrogate</em> characters are ignored. |
| * These are Unicode characters that fall between the values 56192 (db80) |
| * and 56319 (dbff) as we don't know how to handle them. |
| * High and low surrogates are correctly dealt with - that is if a |
| * high surrogate is randomly chosen, 55296 (d800) to 56191 (db7f) |
| * then it is followed by a low surrogate. If a low surrogate is chosen, |
| * 56320 (dc00) to 57343 (dfff) then it is placed after a randomly |
| * chosen high surrogate. </p> |
| * |
| * <p>#ThreadSafe#</p> |
| * @since 1.0 |
| * @version $Id$ |
| */ |
| public class RandomStringUtils { |
| |
| /** |
| * <p>Random object used by random method. This has to be not local |
| * to the random method so as to not return the same value in the |
| * same millisecond.</p> |
| */ |
| private static final Random RANDOM = new Random(); |
| |
| /** |
| * <p>{@code RandomStringUtils} instances should NOT be constructed in |
| * standard programming. Instead, the class should be used as |
| * {@code RandomStringUtils.random(5);}.</p> |
| * |
| * <p>This constructor is public to permit tools that require a JavaBean instance |
| * to operate.</p> |
| */ |
| public RandomStringUtils() { |
| super(); |
| } |
| |
| // Random |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of all characters.</p> |
| * |
| * @param count the length of random string to create |
| * @return the random string |
| */ |
| public static String random(int count) { |
| return random(count, false, false); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of characters whose |
| * ASCII value is between {@code 32} and {@code 126} (inclusive).</p> |
| * |
| * @param count the length of random string to create |
| * @return the random string |
| */ |
| public static String randomAscii(int count) { |
| return random(count, 32, 127, false, false); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of alphabetic |
| * characters.</p> |
| * |
| * @param count the length of random string to create |
| * @return the random string |
| */ |
| public static String randomAlphabetic(int count) { |
| return random(count, true, false); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of alpha-numeric |
| * characters.</p> |
| * |
| * @param count the length of random string to create |
| * @return the random string |
| */ |
| public static String randomAlphanumeric(int count) { |
| return random(count, true, true); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of numeric |
| * characters.</p> |
| * |
| * @param count the length of random string to create |
| * @return the random string |
| */ |
| public static String randomNumeric(int count) { |
| return random(count, false, true); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of alpha-numeric |
| * characters as indicated by the arguments.</p> |
| * |
| * @param count the length of random string to create |
| * @param letters if {@code true}, generated string will include |
| * alphabetic characters |
| * @param numbers if {@code true}, generated string will include |
| * numeric characters |
| * @return the random string |
| */ |
| public static String random(int count, boolean letters, boolean numbers) { |
| return random(count, 0, 0, letters, numbers); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of alpha-numeric |
| * characters as indicated by the arguments.</p> |
| * |
| * @param count the length of random string to create |
| * @param start the position in set of chars to start at |
| * @param end the position in set of chars to end before |
| * @param letters if {@code true}, generated string will include |
| * alphabetic characters |
| * @param numbers if {@code true}, generated string will include |
| * numeric characters |
| * @return the random string |
| */ |
| public static String random(int count, int start, int end, boolean letters, boolean numbers) { |
| return random(count, start, end, letters, numbers, null, RANDOM); |
| } |
| |
| /** |
| * <p>Creates a random string based on a variety of options, using |
| * default source of randomness.</p> |
| * |
| * <p>This method has exactly the same semantics as |
| * {@link #random(int,int,int,boolean,boolean,char[],Random)}, but |
| * instead of using an externally supplied source of randomness, it uses |
| * the internal static {@link Random} instance.</p> |
| * |
| * @param count the length of random string to create |
| * @param start the position in set of chars to start at |
| * @param end the position in set of chars to end before |
| * @param letters only allow letters? |
| * @param numbers only allow numbers? |
| * @param chars the set of chars to choose randoms from. |
| * If {@code null}, then it will use the set of all chars. |
| * @return the random string |
| * @throws ArrayIndexOutOfBoundsException if there are not |
| * {@code (end - start) + 1} characters in the set array. |
| */ |
| public static String random(int count, int start, int end, boolean letters, boolean numbers, char[] chars) { |
| return random(count, start, end, letters, numbers, chars, RANDOM); |
| } |
| |
| /** |
| * <p>Creates a random string based on a variety of options, using |
| * supplied source of randomness.</p> |
| * |
| * <p>If start and end are both {@code 0}, start and end are set |
| * to {@code ' '} and {@code 'z'}, the ASCII printable |
| * characters, will be used, unless letters and numbers are both |
| * {@code false}, in which case, start and end are set to |
| * {@code 0} and {@code Integer.MAX_VALUE}. |
| * |
| * <p>If set is not {@code null}, characters between start and |
| * end are chosen.</p> |
| * |
| * <p>This method accepts a user-supplied {@link Random} |
| * instance to use as a source of randomness. By seeding a single |
| * {@link Random} instance with a fixed seed and using it for each call, |
| * the same random sequence of strings can be generated repeatedly |
| * and predictably.</p> |
| * |
| * @param count the length of random string to create |
| * @param start the position in set of chars to start at |
| * @param end the position in set of chars to end before |
| * @param letters only allow letters? |
| * @param numbers only allow numbers? |
| * @param chars the set of chars to choose randoms from, must not be empty. |
| * If {@code null}, then it will use the set of all chars. |
| * @param random a source of randomness. |
| * @return the random string |
| * @throws ArrayIndexOutOfBoundsException if there are not |
| * {@code (end - start) + 1} characters in the set array. |
| * @throws IllegalArgumentException if {@code count} < 0 or the provided chars array is empty. |
| * @since 2.0 |
| */ |
| public static String random(int count, int start, int end, boolean letters, boolean numbers, |
| char[] chars, Random random) { |
| if (count == 0) { |
| return ""; |
| } else if (count < 0) { |
| throw new IllegalArgumentException("Requested random string length " + count + " is less than 0."); |
| } |
| if (chars != null && chars.length == 0) { |
| throw new IllegalArgumentException("The chars array must not be empty"); |
| } |
| |
| if (start == 0 && end == 0) { |
| if (chars != null) { |
| end = chars.length; |
| } else { |
| if (!letters && !numbers) { |
| end = Integer.MAX_VALUE; |
| } else { |
| end = 'z' + 1; |
| start = ' '; |
| } |
| } |
| } else { |
| if (end <= start) { |
| throw new IllegalArgumentException("Parameter end (" + end + ") must be greater than start (" + start + ")"); |
| } |
| } |
| |
| char[] buffer = new char[count]; |
| int gap = end - start; |
| |
| while (count-- != 0) { |
| char ch; |
| if (chars == null) { |
| ch = (char) (random.nextInt(gap) + start); |
| } else { |
| ch = chars[random.nextInt(gap) + start]; |
| } |
| if (letters && Character.isLetter(ch) |
| || numbers && Character.isDigit(ch) |
| || !letters && !numbers) { |
| if(ch >= 56320 && ch <= 57343) { |
| if(count == 0) { |
| count++; |
| } else { |
| // low surrogate, insert high surrogate after putting it in |
| buffer[count] = ch; |
| count--; |
| buffer[count] = (char) (55296 + random.nextInt(128)); |
| } |
| } else if(ch >= 55296 && ch <= 56191) { |
| if(count == 0) { |
| count++; |
| } else { |
| // high surrogate, insert low surrogate before putting it in |
| buffer[count] = (char) (56320 + random.nextInt(128)); |
| count--; |
| buffer[count] = ch; |
| } |
| } else if(ch >= 56192 && ch <= 56319) { |
| // private high surrogate, no effing clue, so skip it |
| count++; |
| } else { |
| buffer[count] = ch; |
| } |
| } else { |
| count++; |
| } |
| } |
| return new String(buffer); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of characters |
| * specified by the string, must not be empty. |
| * If null, the set of all characters is used.</p> |
| * |
| * @param count the length of random string to create |
| * @param chars the String containing the set of characters to use, |
| * may be null, but must not be empty |
| * @return the random string |
| * @throws IllegalArgumentException if {@code count} < 0 or the string is empty. |
| */ |
| public static String random(int count, String chars) { |
| if (chars == null) { |
| return random(count, 0, 0, false, false, null, RANDOM); |
| } |
| return random(count, chars.toCharArray()); |
| } |
| |
| /** |
| * <p>Creates a random string whose length is the number of characters |
| * specified.</p> |
| * |
| * <p>Characters will be chosen from the set of characters specified.</p> |
| * |
| * @param count the length of random string to create |
| * @param chars the character array containing the set of characters to use, |
| * may be null |
| * @return the random string |
| * @throws IllegalArgumentException if {@code count} < 0. |
| */ |
| public static String random(int count, char[] chars) { |
| if (chars == null) { |
| return random(count, 0, 0, false, false, null, RANDOM); |
| } |
| return random(count, 0, chars.length, false, false, chars, RANDOM); |
| } |
| |
| } |
