RandomUtils.java
/*
* 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.lang3;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.Security;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Supplier;
import org.apache.commons.lang3.exception.UncheckedException;
/**
* Supplements the standard {@link Random} class.
* <p>
* Use {@link #secure()} to get the singleton instance based on {@link SecureRandom#SecureRandom()} which uses a secure random number generator implementing the
* default random number algorithm.
* </p>
* <p>
* Use {@link #secureStrong()} to get the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an instance that was selected by using
* the algorithms/providers specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
* </p>
* <p>
* Use {@link #insecure()} to get the singleton instance based on {@link ThreadLocalRandom#current()} <b>which is not cryptographically secure</b>. In addition,
* instances do not use a cryptographically random seed unless the {@linkplain System#getProperty system property} {@code java.util.secureRandomSeed} is set to
* {@code true}.
* </p>
* <p>
* Starting in version 3.17.0, the method {@link #secure()} uses {@link SecureRandom#SecureRandom()} instead of {@link SecureRandom#getInstanceStrong()}, and
* adds {@link #secureStrong()}.
* </p>
* <p>
* Starting in version 3.16.0, this class uses {@link #secure()} for static methods and adds {@link #insecure()}.
* </p>
* <p>
* Starting in version 3.15.0, this class uses {@link SecureRandom#getInstanceStrong()} for static methods.
* </p>
* <p>
* Before version 3.15.0, this class used {@link ThreadLocalRandom#current()} for static methods, which is not cryptographically secure.
* </p>
* <p>
* Please note that the Apache Commons project provides a component dedicated to pseudo-random number generation, namely
* <a href="https://commons.apache.org/proper/commons-rng/">Commons RNG</a>, that may be a better choice for applications with more stringent requirements
* (performance and/or correctness).
* </p>
*
* @see #secure()
* @see #secureStrong()
* @see #insecure()
* @see SecureRandom#SecureRandom()
* @see SecureRandom#getInstanceStrong()
* @see ThreadLocalRandom#current()
* @see RandomStringUtils
* @since 3.3
*/
public class RandomUtils {
private static RandomUtils INSECURE = new RandomUtils(ThreadLocalRandom::current);
private static RandomUtils SECURE = new RandomUtils(SecureRandom::new);
private static final Supplier<Random> SECURE_STRONG_SUPPLIER = () -> RandomUtils.SECURE_RANDOM_STRONG.get();
private static RandomUtils SECURE_STRONG = new RandomUtils(SECURE_STRONG_SUPPLIER);
private static final ThreadLocal<SecureRandom> SECURE_RANDOM_STRONG = ThreadLocal.withInitial(() -> {
try {
return SecureRandom.getInstanceStrong();
} catch (final NoSuchAlgorithmException e) {
throw new UncheckedException(e);
}
});
/**
* Gets the singleton instance based on {@link ThreadLocalRandom#current()}; <b>which is not cryptographically
* secure</b>; use {@link #secure()} to use an algorithms/providers specified in the
* {@code securerandom.strongAlgorithms} {@link Security} property.
* <p>
* The method {@link ThreadLocalRandom#current()} is called on-demand.
* </p>
*
* @return the singleton instance based on {@link ThreadLocalRandom#current()}.
* @see ThreadLocalRandom#current()
* @see #secure()
* @since 3.17.0
*/
public static RandomUtils insecure() {
return INSECURE;
}
/**
* Generates a random boolean value.
*
* @return the random boolean
* @since 3.5
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static boolean nextBoolean() {
return secure().randomBoolean();
}
/**
* Generates an array of random bytes.
*
* @param count the size of the returned array
* @return the random byte array
* @throws IllegalArgumentException if {@code count} is negative
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static byte[] nextBytes(final int count) {
return secure().randomBytes(count);
}
/**
* Generates a random double between 0 (inclusive) and Double.MAX_VALUE (exclusive).
*
* @return the random double
* @see #nextDouble(double, double)
* @since 3.5
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static double nextDouble() {
return secure().randomDouble();
}
/**
* Generates a random double within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random double
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static double nextDouble(final double startInclusive, final double endExclusive) {
return secure().randomDouble(startInclusive, endExclusive);
}
/**
* Generates a random float between 0 (inclusive) and Float.MAX_VALUE (exclusive).
*
* @return the random float
* @see #nextFloat(float, float)
* @since 3.5
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static float nextFloat() {
return secure().randomFloat();
}
/**
* Generates a random float within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random float
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static float nextFloat(final float startInclusive, final float endExclusive) {
return secure().randomFloat(startInclusive, endExclusive);
}
/**
* Generates a random int between 0 (inclusive) and Integer.MAX_VALUE (exclusive).
*
* @return the random integer
* @see #nextInt(int, int)
* @since 3.5
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static int nextInt() {
return secure().randomInt();
}
/**
* Generates a random integer within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random integer
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static int nextInt(final int startInclusive, final int endExclusive) {
return secure().randomInt(startInclusive, endExclusive);
}
/**
* Generates a random long between 0 (inclusive) and Long.MAX_VALUE (exclusive).
*
* @return the random long
* @see #nextLong(long, long)
* @since 3.5
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static long nextLong() {
return secure().randomLong();
}
/**
* Generates a random long within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random long
* @deprecated Use {@link #secure()}, {@link #secureStrong()},or {@link #insecure()}.
*/
@Deprecated
public static long nextLong(final long startInclusive, final long endExclusive) {
return secure().randomLong(startInclusive, endExclusive);
}
/**
* Gets the singleton instance based on {@link SecureRandom#SecureRandom()} which uses an algorithms/providers
* specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
* <p>
* The method {@link SecureRandom#SecureRandom()} is called on-demand.
* </p>
*
* @return the singleton instance based on {@link SecureRandom#SecureRandom()}.
* @see SecureRandom#SecureRandom()
* @since 3.16.0
*/
public static RandomUtils secure() {
return SECURE;
}
static SecureRandom secureRandom() {
return SECURE_RANDOM_STRONG.get();
}
/**
* Gets the singleton instance based on {@link SecureRandom#getInstanceStrong()} which uses an algorithms/providers
* specified in the {@code securerandom.strongAlgorithms} {@link Security} property.
* <p>
* The method {@link SecureRandom#getInstanceStrong()} is called on-demand.
* </p>
*
* @return the singleton instance based on {@link SecureRandom#getInstanceStrong()}.
* @see SecureRandom#getInstanceStrong()
* @since 3.17.0
*/
public static RandomUtils secureStrong() {
return SECURE_STRONG;
}
private final Supplier<Random> random;
/**
* {@link RandomUtils} instances should NOT be constructed in standard programming. Instead, the class should be
* used as {@code RandomUtils.nextBytes(5);}.
* <p>
* This constructor is public to permit tools that require a JavaBean instance to operate.
* </p>
*
* @deprecated TODO Make private in 4.0.
*/
@Deprecated
public RandomUtils() {
this(SECURE_STRONG_SUPPLIER);
}
private RandomUtils(final Supplier<Random> random) {
this.random = random;
}
Random random() {
return random.get();
}
/**
* Generates a random boolean value.
*
* @return the random boolean
* @since 3.16.0
*/
public boolean randomBoolean() {
return random().nextBoolean();
}
/**
* Generates an array of random bytes.
*
* @param count the size of the returned array
* @return the random byte array
* @throws IllegalArgumentException if {@code count} is negative
* @since 3.16.0
*/
public byte[] randomBytes(final int count) {
Validate.isTrue(count >= 0, "Count cannot be negative.");
final byte[] result = new byte[count];
random().nextBytes(result);
return result;
}
/**
* Generates a random double between 0 (inclusive) and Double.MAX_VALUE (exclusive).
*
* @return the random double
* @see #randomDouble(double, double)
* @since 3.16.0
*/
public double randomDouble() {
return randomDouble(0, Double.MAX_VALUE);
}
/**
* Generates a random double within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random double
* @since 3.16.0
*/
public double randomDouble(final double startInclusive, final double endExclusive) {
Validate.isTrue(endExclusive >= startInclusive, "Start value must be smaller or equal to end value.");
Validate.isTrue(startInclusive >= 0, "Both range values must be non-negative.");
if (startInclusive == endExclusive) {
return startInclusive;
}
return startInclusive + (endExclusive - startInclusive) * random().nextDouble();
}
/**
* Generates a random float between 0 (inclusive) and Float.MAX_VALUE (exclusive).
*
* @return the random float
* @see #randomFloat(float, float)
* @since 3.16.0
*/
public float randomFloat() {
return randomFloat(0, Float.MAX_VALUE);
}
/**
* Generates a random float within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random float
*/
public float randomFloat(final float startInclusive, final float endExclusive) {
Validate.isTrue(endExclusive >= startInclusive, "Start value must be smaller or equal to end value.");
Validate.isTrue(startInclusive >= 0, "Both range values must be non-negative.");
if (startInclusive == endExclusive) {
return startInclusive;
}
return startInclusive + (endExclusive - startInclusive) * random().nextFloat();
}
/**
* Generates a random int between 0 (inclusive) and Integer.MAX_VALUE (exclusive).
*
* @return the random integer
* @see #randomInt(int, int)
* @since 3.16.0
*/
public int randomInt() {
return randomInt(0, Integer.MAX_VALUE);
}
/**
* Generates a random integer within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random integer
* @since 3.16.0
*/
public int randomInt(final int startInclusive, final int endExclusive) {
Validate.isTrue(endExclusive >= startInclusive, "Start value must be smaller or equal to end value.");
Validate.isTrue(startInclusive >= 0, "Both range values must be non-negative.");
if (startInclusive == endExclusive) {
return startInclusive;
}
return startInclusive + random().nextInt(endExclusive - startInclusive);
}
/**
* Generates a random long between 0 (inclusive) and Long.MAX_VALUE (exclusive).
*
* @return the random long
* @see #randomLong(long, long)
* @since 3.16.0
*/
public long randomLong() {
return randomLong(Long.MAX_VALUE);
}
/**
* Generates a {@code long} value between 0 (inclusive) and the specified value (exclusive).
*
* @param n Bound on the random number to be returned. Must be positive.
* @return a random {@code long} value between 0 (inclusive) and {@code n} (exclusive).
*/
private long randomLong(final long n) {
// Extracted from o.a.c.rng.core.BaseProvider.nextLong(long)
long bits;
long val;
do {
bits = random().nextLong() >>> 1;
val = bits % n;
} while (bits - val + n - 1 < 0);
return val;
}
/**
* Generates a random long within the specified range.
*
* @param startInclusive the smallest value that can be returned, must be non-negative
* @param endExclusive the upper bound (not included)
* @throws IllegalArgumentException if {@code startInclusive > endExclusive} or if {@code startInclusive} is
* negative
* @return the random long
* @since 3.16.0
*/
public long randomLong(final long startInclusive, final long endExclusive) {
Validate.isTrue(endExclusive >= startInclusive, "Start value must be smaller or equal to end value.");
Validate.isTrue(startInclusive >= 0, "Both range values must be non-negative.");
if (startInclusive == endExclusive) {
return startInclusive;
}
return startInclusive + randomLong(endExclusive - startInclusive);
}
@Override
public String toString() {
return "RandomUtils [random=" + random() + "]";
}
}