ai.platon.pulsar.skeleton.signature.TextMD5Signature Maven / Gradle / Ivy
/**
* 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 ai.platon.pulsar.skeleton.signature;
import ai.platon.pulsar.persist.WebPage;
import org.apache.hadoop.io.MD5Hash;
/**
* Default implementation of a page signature. It calculates an MD5 hash of the
* textual content of a page. In case there is no signature, it calculates a hash
* from the page's fetched content.
*/
public class TextMD5Signature extends Signature {
public static int GOOD_CONTENT_TEXT_LENGTH = 2000;
private Signature fallback = new MD5Signature();
/**
* We need calculate signature using a more clean signature content, eg, extracted by signature-persist
* */
@Override
public byte[] calculate(WebPage page) {
String text = page.getContentText();
if (text.isEmpty() || text.length() < GOOD_CONTENT_TEXT_LENGTH) {
text = page.getPageText();
}
if (text.isEmpty()) {
return fallback.calculate(page);
}
return MD5Hash.digest(text).getDigest();
}
}