1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.any23.extractor.html;
19
20 import org.apache.any23.extractor.ExtractionException;
21 import org.apache.any23.extractor.ExtractionResult;
22 import org.apache.any23.rdf.RDFUtils;
23 import org.eclipse.rdf4j.model.BNode;
24 import org.w3c.dom.Node;
25
26 import java.util.List;
27
28 /**
29 * Base class for microformat extractors based on entities.
30 *
31 * @author Gabriele Renzi
32 */
33 public abstract class EntityBasedMicroformatExtractor extends MicroformatExtractor {
34
35 /**
36 * Returns the base class name for the extractor.
37 *
38 * @return a string containing the base of the extractor.
39 */
40 protected abstract String getBaseClassName();
41
42 /**
43 * Resets the internal status of the extractor to prepare it to a new extraction section.
44 */
45 protected abstract void resetExtractor();
46
47 /**
48 * Extracts an entity from a <i>DOM</i> node.
49 *
50 * @param node
51 * the DOM node.
52 * @param out
53 * the extraction result collector.
54 *
55 * @return <code>true</code> if the extraction has produces something, <code>false</code> otherwise.
56 *
57 * @throws ExtractionException
58 * if there is an error during extraction
59 */
60 protected abstract boolean extractEntity(Node node, ExtractionResult out) throws ExtractionException;
61
62 @Override
63 public boolean extract() throws ExtractionException {
64 List<Node> nodes = DomUtils.findAllByClassName(getHTMLDocument().getDocument(), getBaseClassName());
65 boolean foundAny = false;
66 int count = 1;
67 for (Node node : nodes) {
68 resetExtractor();
69 String contextID = Integer.toString(count);
70 ExtractionResult subResult = openSubResult(getExtractionContext().copy(contextID));
71 foundAny |= extractEntity(node, subResult);
72 subResult.close();
73 count++;
74 }
75 return foundAny;
76 }
77
78 /**
79 * @param node
80 * a DOM node representing a blank node
81 *
82 * @return an RDF blank node corresponding to that DOM node, by using a blank node ID like "MD5 of
83 * http://doc-uri/#xpath/to/node"
84 */
85 protected BNode getBlankNodeFor(Node node) {
86 return RDFUtils.getBNode(getDocumentIRI() + "#" + DomUtils.getXPathForNode(node));
87 }
88
89 }