opennlp.model.HashSumEventStream Maven / Gradle / Ivy
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/*
* 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.model;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import opennlp.model.Event;
import opennlp.model.EventStream;
public class HashSumEventStream implements EventStream {
private final EventStream eventStream;
private MessageDigest digest;
public HashSumEventStream(EventStream eventStream) {
this.eventStream = eventStream;
try {
digest = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
// should never happen, does all java runtimes have md5 ?!
throw new IllegalStateException(e);
}
}
public boolean hasNext() throws IOException {
return eventStream.hasNext();
}
public Event next() throws IOException {
Event event = eventStream.next();
try {
digest.update(event.toString().getBytes("UTF-8"));
}
catch (UnsupportedEncodingException e) {
throw new IllegalStateException("UTF-8 encoding is not available!", e);
}
return event;
}
/**
* Calculates the hash sum of the stream. The method must be
* called after the stream is completely consumed.
*
* @return the hash sum
* @throws IllegalStateException if the stream is not consumed completely,
* completely means that hasNext() returns false
*/
public BigInteger calculateHashSum() {
// if (hasNext())
// throw new IllegalStateException("stream must be consumed completely!");
return new BigInteger(1, digest.digest());
}
public void remove() {
}
}
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