| /* |
| * 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.rng.core.source32; |
| |
| import java.util.Random; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.ObjectOutputStream; |
| import java.io.ObjectStreamClass; |
| import java.io.ObjectInputStream; |
| import java.io.ByteArrayOutputStream; |
| |
| import org.apache.commons.rng.core.util.NumberFactory; |
| |
| import java.io.ByteArrayInputStream; |
| |
| /** |
| * A provider that uses the {@link Random#nextInt()} method of the JDK's |
| * {@link Random} class as the source of randomness. |
| * |
| * <p> |
| * <b>Caveat:</b> All the other calls will be redirected to the methods |
| * implemented within this library. |
| * </p> |
| * |
| * <p> |
| * The state of this source of randomness is saved and restored through |
| * the serialization of the {@link Random} instance. |
| * </p> |
| * |
| * @since 1.0 |
| */ |
| public class JDKRandom extends IntProvider { |
| /** Delegate. Cannot be "final" (to allow serialization). */ |
| private Random delegate; |
| |
| /** |
| * An <code>ObjectInputStream</code> that's restricted to deserialize |
| * only {@link java.util.Random} using look-ahead deserialization. |
| * |
| * <p>Adapted from o.a.c.io.serialization.ValidatingObjectInputStream.</p> |
| * |
| * @see <a href="http://www.ibm.com/developerworks/library/se-lookahead/"> |
| * IBM DeveloperWorks Article: Look-ahead Java deserialization</a> |
| */ |
| private static class ValidatingObjectInputStream extends ObjectInputStream { |
| /** |
| * @param in Input stream |
| * @throws IOException Signals that an I/O exception has occurred. |
| */ |
| ValidatingObjectInputStream(final InputStream in) throws IOException { |
| super(in); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| protected Class<?> resolveClass(final ObjectStreamClass osc) throws IOException, |
| ClassNotFoundException { |
| // For legacy reasons the Random class is serialized using only primitives |
| // even though modern implementations use AtomicLong. |
| // The only expected class is java.util.Random. |
| if (!Random.class.getName().equals(osc.getName())) { |
| throw new IllegalStateException("Stream does not contain java.util.Random: " + osc.getName()); |
| } |
| return super.resolveClass(osc); |
| } |
| } |
| |
| /** |
| * Creates an instance with the given seed. |
| * |
| * @param seed Initial seed. |
| */ |
| public JDKRandom(Long seed) { |
| delegate = new Random(seed); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @see Random#nextInt() |
| */ |
| @Override |
| public int next() { |
| return delegate.nextInt(); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| protected byte[] getStateInternal() { |
| try { |
| final ByteArrayOutputStream bos = new ByteArrayOutputStream(); |
| final ObjectOutputStream oos = new ObjectOutputStream(bos); |
| |
| // Serialize the "delegate". |
| oos.writeObject(delegate); |
| |
| final byte[] state = bos.toByteArray(); |
| final int stateSize = state.length; // To allow state recovery. |
| // Compose the size with the state |
| final byte[] sizeAndState = composeStateInternal(NumberFactory.makeByteArray(stateSize), |
| state); |
| return composeStateInternal(sizeAndState, |
| super.getStateInternal()); |
| } catch (IOException e) { |
| // Workaround checked exception. |
| throw new IllegalStateException(e); |
| } |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| protected void setStateInternal(byte[] s) { |
| // First obtain the state size |
| final byte[][] s2 = splitStateInternal(s, 4); |
| final int stateSize = NumberFactory.makeInt(s2[0]); |
| |
| // Second obtain the state |
| final byte[][] c = splitStateInternal(s2[1], stateSize); |
| |
| // Use look-ahead deserialization to validate the state byte[] contains java.util.Random. |
| try { |
| final ByteArrayInputStream bis = new ByteArrayInputStream(c[0]); |
| final ObjectInputStream ois = new ValidatingObjectInputStream(bis); |
| |
| delegate = (Random) ois.readObject(); |
| } catch (ClassNotFoundException e) { |
| // Workaround checked exception. |
| throw new IllegalStateException(e); |
| } catch (IOException e) { |
| // Workaround checked exception. |
| throw new IllegalStateException(e); |
| } |
| |
| super.setStateInternal(c[1]); |
| } |
| } |