/**
* 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.nutch.parse.headings;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.*;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.parse.HTMLMetaTags;
import org.apache.nutch.parse.Parse;
import org.apache.nutch.parse.HtmlParseFilter;
import org.apache.nutch.parse.ParseResult;
import org.apache.nutch.protocol.Content;
import org.apache.nutch.util.NodeWalker;
import org.w3c.dom.*;
/**
* HtmlParseFilter to retrieve h1 and h2 values from the DOM.
*/
public class HeadingsParseFilter implements HtmlParseFilter {
/**
* Pattern used to strip surpluss whitespace
*/
protected static Pattern whitespacePattern = Pattern.compile("\\s+");
private Configuration conf;
private String[] headings;
private boolean multiValued = false;
public ParseResult filter(Content content, ParseResult parseResult, HTMLMetaTags metaTags, DocumentFragment doc) {
Parse parse = parseResult.get(content.getUrl());
for (int i = 0 ; headings != null && i < headings.length ; i++ ) {
List<String> discoveredHeadings = getElement(doc, headings[i]);
if (discoveredHeadings.size() > 0) {
for (String heading : discoveredHeadings) {
if (heading != null) {
heading.trim();
if (heading.length() > 0) {
parse.getData().getParseMeta().add(headings[i], heading);
}
}
}
}
}
return parseResult;
}
public void setConf(Configuration conf) {
this.conf = conf;
headings = conf.getStrings("headings");
multiValued = conf.getBoolean("headings.multivalued", false);
}
public Configuration getConf() {
return this.conf;
}
/**
* Finds the specified element and returns its value
*/
protected List<String> getElement(DocumentFragment doc, String element) {
List<String> headings = new ArrayList<String>();
NodeWalker walker = new NodeWalker(doc);
while (walker.hasNext()) {
Node currentNode = walker.nextNode();
if (currentNode.getNodeType() == Node.ELEMENT_NODE) {
if (element.equalsIgnoreCase(currentNode.getNodeName())) {
headings.add(getNodeValue(currentNode));
// Check for multiValued here, if disabled we don't need
// to discover more headings.
if (!multiValued) {
break;
}
}
}
}
return headings;
}
/**
* Returns the text value of the specified Node and child nodes
*/
protected static String getNodeValue(Node node) {
StringBuilder buffer = new StringBuilder();
NodeList children = node.getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
if (children.item(i).getNodeType() == Node.TEXT_NODE) {
buffer.append(children.item(i).getNodeValue());
}
}
// Return with stripped surplus whitespace
Matcher matcher = whitespacePattern.matcher(buffer.toString().trim());
return matcher.replaceAll(" ").trim();
}
}