| /* |
| * 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 opennlp.tools.ml.model; |
| |
| import java.io.IOException; |
| import java.math.BigInteger; |
| import java.nio.charset.StandardCharsets; |
| import java.security.MessageDigest; |
| import java.security.NoSuchAlgorithmException; |
| |
| import opennlp.tools.util.AbstractObjectStream; |
| import opennlp.tools.util.ObjectStream; |
| |
| /** |
| * A hash sum based {@link AbstractObjectStream} implementation. |
| * |
| * @see Event |
| * @see MessageDigest |
| * @see AbstractObjectStream |
| */ |
| public class HashSumEventStream extends AbstractObjectStream<Event> { |
| |
| private final MessageDigest digest; |
| |
| public HashSumEventStream(ObjectStream<Event> eventStream) { |
| super(eventStream); |
| |
| try { |
| digest = MessageDigest.getInstance("MD5"); |
| } catch (NoSuchAlgorithmException e) { |
| // should never happen: do all java runtimes have md5 ?! |
| throw new IllegalStateException(e); |
| } |
| } |
| |
| @Override |
| public Event read() throws IOException { |
| Event event = super.read(); |
| |
| if (event != null) { |
| digest.update(event.toString().getBytes(StandardCharsets.UTF_8)); |
| } |
| |
| return event; |
| } |
| |
| /** |
| * Calculates the hash sum of the stream and wraps it into a {@link BigInteger}. |
| * Note: The method must be called after the stream is completely consumed. |
| * |
| * @return The calculated hash sum as {@link BigInteger}. |
| * @throws IllegalStateException Thrown if the stream is not consumed completely, |
| * completely means that hasNext() returns {@code false}. |
| */ |
| public BigInteger calculateHashSum() { |
| return new BigInteger(1, digest.digest()); |
| } |
| |
| } |