/**
* 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.crawl;
import java.io.IOException;
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.nutch.net.URLFilters;
import org.apache.nutch.net.URLNormalizers;
/**
* This class provides a way to separate the URL normalization
* and filtering steps from the rest of LinkDb manipulation code.
*
* @author Andrzej Bialecki
*/
public class LinkDbFilter implements Mapper {
public static final String URL_FILTERING = "linkdb.url.filters";
public static final String URL_NORMALIZING = "linkdb.url.normalizer";
public static final String URL_NORMALIZING_SCOPE = "linkdb.url.normalizer.scope";
private boolean filter;
private boolean normalize;
private URLFilters filters;
private URLNormalizers normalizers;
private JobConf jobConf;
private String scope;
public static final Log LOG = LogFactory.getLog(LinkDbFilter.class);
public void configure(JobConf job) {
this.jobConf = job;
filter = job.getBoolean(URL_FILTERING, false);
normalize = job.getBoolean(URL_NORMALIZING, false);
if (filter) {
filters = new URLFilters(job);
}
if (normalize) {
scope = job.get(URL_NORMALIZING_SCOPE, URLNormalizers.SCOPE_LINKDB);
normalizers = new URLNormalizers(job, scope);
}
}
public void close() {}
public void map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) throws IOException {
String url = key.toString();
if (normalize) {
try {
url = normalizers.normalize(url, scope); // normalize the url
} catch (Exception e) {
LOG.warn("Skipping " + url + ":" + e);
url = null;
}
}
if (url != null && filter) {
try {
url = filters.filter(url); // filter the url
} catch (Exception e) {
LOG.warn("Skipping " + url + ":" + e);
url = null;
}
}
if (url == null) return; // didn't pass the filters
Inlinks inlinks = (Inlinks)value;
Iterator it = inlinks.iterator();
String fromUrl = null;
while (it.hasNext()) {
Inlink inlink = (Inlink)it.next();
fromUrl = inlink.getFromUrl();
if (normalize) {
try {
fromUrl = normalizers.normalize(fromUrl, scope); // normalize the url
} catch (Exception e) {
LOG.warn("Skipping " + fromUrl + ":" + e);
fromUrl = null;
}
}
if (fromUrl != null && filter) {
try {
fromUrl = filters.filter(fromUrl); // filter the url
} catch (Exception e) {
LOG.warn("Skipping " + fromUrl + ":" + e);
fromUrl = null;
}
}
if (fromUrl == null) { // should be discarded
it.remove();
}
}
if (inlinks.size() == 0) return; // don't collect empy inlinks
output.collect(key, inlinks);
}
}