/**
* Copyright 2006 The Apache Software Foundation
*
* Licensed 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.urlfilter.suffix;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.net.*;
import org.apache.nutch.util.NutchConfiguration;
import org.apache.nutch.util.SuffixStringMatcher;
import org.apache.nutch.util.TrieStringMatcher;
import org.apache.nutch.plugin.Extension;
import org.apache.nutch.plugin.PluginRepository;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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 suffixes. The file is named by
* <ol>
* <li>property "urlfilter.suffix.file" in ./conf/nutch-default.xml, and</li>
* <li>attribute "file" in plugin.xml of this plugin</li>
* </ol>
* Attribute "file" has higher precedence if defined. If the config file is
* missing, all URLs will be rejected.
*
* <p>This filter can be configured to work in one of two modes:
* <ul>
* <li><b>default to reject</b> ('-'): in this mode, only URLs that match suffixes
* specified in the config file will be accepted, all other URLs will be
* rejected.</li>
* <li><b>default to accept</b> ('+'): in this mode, only URLs that match suffixes
* specified in the config file will be rejected, all other URLs will be
* accepted.</li>
* </ul>
* <p>
* The format of this config file is one URL suffix per line, with no preceding
* whitespace. Order, in which suffixes are specified, doesn't matter. Blank
* lines and comments (#) are allowed.
* </p>
* <p>
* A single '+' or '-' sign not followed by any suffix must be used once, to
* signify the mode this plugin operates in. An optional single 'I' can be appended,
* to signify that suffix matches should be case-insensitive. The default, if
* not specified, is to use case-sensitive matches, i.e. suffix '.JPG'
* does not match '.jpg'.
* </p>
* <p>
* NOTE: the format of this file is different from urlfilter-prefix, because
* that plugin doesn't support allowed/prohibited prefixes (only supports
* allowed prefixes). Please note that this plugin does not support regular
* expressions, it only accepts literal suffixes. I.e. a suffix "+*.jpg" is most
* probably wrong, you should use "+.jpg" instead.
* </p>
* <h4>Example 1</h4>
* <p>
* The configuration shown below will accept all URLs with '.html' or '.htm'
* suffixes (case-sensitive - '.HTML' or '.HTM' will be rejected),
* and prohibit all other suffixes.
* <p>
*
* <pre>
* # this is a comment
*
* # prohibit all unknown, case-sensitive matching
* -
*
* # collect only HTML files.
* .html
* .htm
* </pre>
*
* </p>
* <h4>Example 2</h4>
* <p>
* The configuration shown below will accept all URLs except common graphical
* formats.
* <p>
*
* <pre>
* # this is a comment
*
* # allow all unknown, case-insensitive matching
* +I
*
* # prohibited suffixes
* .gif
* .png
* .jpg
* .jpeg
* .bmp
* </pre>
*
* </p>
* @author Andrzej Bialecki
*/
public class SuffixURLFilter implements URLFilter {
private static final Log LOG = LogFactory.getLog(SuffixURLFilter.class);
// read in attribute "file" of this plugin.
private String attributeFile = null;
private SuffixStringMatcher suffixes;
private boolean modeAccept = false;
private boolean ignoreCase = false;
private Configuration conf;
public SuffixURLFilter() throws IOException {
}
public SuffixURLFilter(Reader reader) throws IOException {
readConfigurationFile(reader);
}
public String filter(String url) {
if (url == null) return null;
String _url;
if (ignoreCase)
_url = url.toLowerCase();
else _url = url;
String a = suffixes.shortestMatch(_url);
if (a == null) {
if (modeAccept) return url;
else return null;
} else {
if (modeAccept) return null;
else return url;
}
}
public void readConfigurationFile(Reader reader) throws IOException {
// handle missing config file
if (reader == null) {
if (LOG.isWarnEnabled()) {
LOG.warn("Missing urlfilter.suffix.file, all URLs will be rejected!");
}
suffixes = new SuffixStringMatcher(new String[0]);
modeAccept = false;
ignoreCase = false;
return;
}
BufferedReader in = new BufferedReader(reader);
List aSuffixes = new ArrayList();
boolean allow = false;
boolean ignore = false;
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
break;
case '-':
allow = false;
if (line.length() > 1 && line.charAt(1) == 'I')
ignore = true;
break;
case '+':
allow = true;
if (line.length() > 1 && line.charAt(1) == 'I')
ignore = true;
break;
default:
aSuffixes.add(line);
}
}
if (ignore) {
for (int i = 0; i < aSuffixes.size(); i++) {
aSuffixes.set(i, ((String) aSuffixes.get(i)).toLowerCase());
}
}
suffixes = new SuffixStringMatcher(aSuffixes);
modeAccept = allow;
ignoreCase = ignore;
}
public static void main(String args[]) throws IOException {
SuffixURLFilter filter;
if (args.length >= 1)
filter = new SuffixURLFilter(new FileReader(args[0]));
else {
filter = new SuffixURLFilter();
filter.setConf(NutchConfiguration.create());
}
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("ACCEPTED " + out);
} else {
System.out.println("REJECTED " + out);
}
}
}
public void setConf(Configuration conf) {
this.conf = conf;
String pluginName = "urlfilter-suffix";
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.suffix.file");
// attribute "file" takes precedence if defined
if (attributeFile != null) file = attributeFile;
Reader reader = conf.getConfResourceAsReader(file);
try {
readConfigurationFile(reader);
} catch (IOException e) {
if (LOG.isFatalEnabled()) { LOG.fatal(e.getMessage()); }
throw new RuntimeException(e.getMessage(), e);
}
}
public Configuration getConf() {
return this.conf;
}
public boolean isModeAccept() {
return modeAccept;
}
public void setModeAccept(boolean modeAccept) {
this.modeAccept = modeAccept;
}
public boolean isIgnoreCase() {
return ignoreCase;
}
public void setIgnoreCase(boolean ignoreCase) {
this.ignoreCase = ignoreCase;
}
}