/**
* 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.
*/
// $Id: PrefixURLFilter.java 823614 2009-10-09 17:02:32Z ab $
package org.apache.nutch.urlfilter.prefix;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.net.*;
import org.apache.nutch.util.PrefixStringMatcher;
import org.apache.nutch.util.TrieStringMatcher;
import org.apache.nutch.plugin.Extension;
import org.apache.nutch.plugin.PluginRepository;
import java.io.Reader;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
/**
* Filters URLs based on a file of URL prefixes. The file is named by
* (1) property "urlfilter.prefix.file" in ./conf/nutch-default.xml, and
* (2) attribute "file" in plugin.xml of this plugin
* Attribute "file" has higher precedence if defined.
*
* <p>The format of this file is one URL prefix per line.</p>
*/
public class PrefixURLFilter implements URLFilter {
private static final Log LOG = LogFactory.getLog(PrefixURLFilter.class);
// read in attribute "file" of this plugin.
private static String attributeFile = null;
private TrieStringMatcher trie;
private Configuration conf;
public PrefixURLFilter() throws IOException {
}
public PrefixURLFilter(String filename) throws IOException {
trie = readConfigurationFile(new FileReader(filename));
}
public String filter(String url) {
if (trie.shortestMatch(url) == null)
return null;
else
return url;
}
private TrieStringMatcher readConfigurationFile(Reader reader)
throws IOException {
BufferedReader in=new BufferedReader(reader);
List urlprefixes = new ArrayList();
String line;
while((line=in.readLine())!=null) {
if (line.length() == 0)
continue;
char first=line.charAt(0);
switch (first) {
case ' ' : case '\n' : case '#' : // skip blank & comment lines
continue;
default :
urlprefixes.add(line);
}
}
return new PrefixStringMatcher(urlprefixes);
}
public static void main(String args[])
throws IOException {
PrefixURLFilter filter;
if (args.length >= 1)
filter = new PrefixURLFilter(args[0]);
else
filter = new PrefixURLFilter();
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
String line;
while((line=in.readLine())!=null) {
String out=filter.filter(line);
if(out!=null) {
System.out.println(out);
}
}
}
public void setConf(Configuration conf) {
this.conf = conf;
String pluginName = "urlfilter-prefix";
Extension[] extensions = PluginRepository.get(conf).getExtensionPoint(
URLFilter.class.getName()).getExtensions();
for (int i = 0; i < extensions.length; i++) {
Extension extension = extensions[i];
if (extension.getDescriptor().getPluginId().equals(pluginName)) {
attributeFile = extension.getAttribute("file");
break;
}
}
if (attributeFile != null && attributeFile.trim().equals(""))
attributeFile = null;
if (attributeFile != null) {
if (LOG.isInfoEnabled()) {
LOG.info("Attribute \"file\" is defined for plugin " + pluginName
+ " as " + attributeFile);
}
} else {
// if (LOG.isWarnEnabled()) {
// LOG.warn("Attribute \"file\" is not defined in plugin.xml for
// plugin "+pluginName);
// }
}
String file = conf.get("urlfilter.prefix.file");
// attribute "file" takes precedence if defined
if (attributeFile != null)
file = attributeFile;
Reader reader = conf.getConfResourceAsReader(file);
if (reader == null) {
trie = new PrefixStringMatcher(new String[0]);
} else {
try {
trie = readConfigurationFile(reader);
} catch (IOException e) {
if (LOG.isFatalEnabled()) { LOG.fatal(e.getMessage()); }
// TODO mb@media-style.com: throw Exception? Because broken api.
throw new RuntimeException(e.getMessage(), e);
}
}
}
public Configuration getConf() {
return this.conf;
}
}