hu.icellmobilsoft.coffee.se.util.string.RandomUtil Maven / Gradle / Ivy
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* #%L
* Coffee
* %%
* Copyright (C) 2020 - 2024 i-Cell Mobilsoft Zrt.
* %%
* Licensed 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
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*/
package hu.icellmobilsoft.coffee.se.util.string;
import java.lang.management.ManagementFactory;
import java.util.Date;
import java.util.Random;
import java.util.UUID;
import org.apache.commons.lang3.StringUtils;
import hu.icellmobilsoft.coffee.se.logging.Logger;
/**
* Util class for generating random Strings
*
* @author imre.scheffer
* @since 1.0.0
*/
public class RandomUtil {
private static Logger LOGGER = Logger.getLogger(RandomUtil.class);
/** Constant DATE_2013_01_01=1356998400000l */
public static long DATE_2013_01_01 = 1356998400000l;
private static final int RADIX = 36;
// [0-9a-zA-Z]
/** Constant MAX_NUM_SYS=62 */
public static final int MAX_NUM_SYS = 62;
// [a-z]
/** Constant LOWERCASE */
public static final char[] LOWERCASE;
// [A-Z]
/** Constant UPPERCASE */
public static final char[] UPPERCASE;
// [0-9a-zA-Z]
/** Constant ALL_LETTER */
public static final char[] ALL_LETTER;
/** Constant ALL_LETTER_STRING="" */
public static final String ALL_LETTER_STRING;
/** Constant generatedIndex=0 */
public static int generatedIndex = 0;
/** Constant PID= */
public static final int PID;
/** Constant PID62="" */
protected static final String PID62;
/** Constant PID36="" */
protected static final String PID36;
/* init */
static {
UPPERCASE = new char[26];
for (int i = 65; i < 65 + 26; i++) {
UPPERCASE[i - 65] = (char) i;
}
LOWERCASE = new char[26];
for (int i = 97; i < 97 + 26; i++) {
LOWERCASE[i - 97] = (char) i;
}
ALL_LETTER = new char[MAX_NUM_SYS];
for (int i = 48; i < 48 + 10; i++) {
ALL_LETTER[i - 48] = (char) i;
}
for (int i = 10; i < 10 + 26; i++) {
ALL_LETTER[i] = UPPERCASE[i - 10];
}
for (int i = 10 + 26; i < 10 + 26 + 26; i++) {
ALL_LETTER[i] = LOWERCASE[i - 10 - 26];
}
ALL_LETTER_STRING = new String(ALL_LETTER);
PID = Integer.valueOf(ManagementFactory.getRuntimeMXBean().getName().split("@")[0]);
/* pid */
// maxpid = 238327
PID62 = paddL(convertToRadix(PID, MAX_NUM_SYS), 3, '0').substring(0, 3);
// maxpid
PID36 = paddL(convertToRadix(PID, RADIX), 3, '0').substring(0, 3);
}
private static final Random RANDOM = new Random();
/**
* Default constructor, constructs a new object.
*/
public RandomUtil() {
super();
}
/**
* Generates fix 16 length id.
*
* @return generated id
*/
public static String generateId() {
int xInd = getNextIndex();
Date xDate = new Date();
xDate.setTime(xDate.getTime() - DATE_2013_01_01);
/* time based */
String xRes = convertToRadix(xDate.getTime(), RADIX);
// 8888 is sufficient with 8 characters :) 7 characters are enough for up to 2081.
xRes = paddL(xRes, 8, '0');
StringBuilder builder = new StringBuilder();
builder.append(xRes);
// nano, we truncate the last 4 characters because they change within milliseconds
Long nano = System.nanoTime();
String xNano = convertToRadix(nano, RADIX);
builder.append(xNano.substring(xNano.length() - 4, xNano.length()));
/* random */
// 2
builder.append(paddL(convertToRadix(RANDOM.nextInt(RADIX * RADIX), RADIX), 2, '0'));
/* generation index */
builder.append(paddL(convertToRadix(xInd, RADIX), 2, '0'));
return builder.toString();
}
/**
* Generates sequential index. Restarts sequence when value greater than 1295.
*
* @return next index
*/
protected static synchronized int getNextIndex() {
generatedIndex++;
// MAX a ZZ
if (generatedIndex > RADIX * RADIX - 1) {
generatedIndex = 0;
}
return generatedIndex;
}
/**
* Applies left padding to given text.
*
* @param str
* text to pad
* @param length
* pad length
* @param padd
* pad charachter
* @return left-padded text
*/
protected static String paddL(String str, int length, char padd) {
/*
* String result = str; while (result.length() < length) { result = padd + result; } return result;
*/
return StringUtils.leftPad(str, length, padd);
}
/**
* Converts input {@code long} to any number system. Highest available number system is 62.
*
* @param inNum
* {@code long} to convert
* @param radix
* radix of the number system
* @return converted number {@link String}
*/
protected static String convertToRadix(long inNum, long radix) {
if (radix == 0) {
return null;
}
long dig;
long numDivRadix;
long num = inNum;
String result = "";
do {
numDivRadix = num / radix;
dig = ((num % radix) + radix) % radix;
result = ALL_LETTER[(int) dig] + result;
num = numDivRadix;
} while (num != 0);
return result;
}
/**
* Generating random {@link String} token
*
* @return generated token
*/
public static String generateToken() {
String token = StringUtils.left(UUID.randomUUID() + generateId(), 48);
LOGGER.debug("Generated token: [{0}]", token);
return token;
}
}