org.apache.nutch.net.urlnormalizer.host.HostURLNormalizer.java Source code

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Here is the source code for org.apache.nutch.net.urlnormalizer.host.HostURLNormalizer.java

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/**
 * 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.net.urlnormalizer.host;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.net.URLNormalizer;
import org.apache.nutch.plugin.Extension;
import org.apache.nutch.plugin.PluginRepository;
import org.apache.nutch.util.URLUtil;

/**
 * URL normalizer for mapping hosts to their desired form. It takes
 * a simple text file as source in the format:
 *
 * example.org www.example.org
 *
 * mapping all URL's of example.org the the www sub-domain. It also
 * allows for wildcards to be used to map all sub-domains to another
 * host:
 *
 * *.example.org www.example.org
 */
public class HostURLNormalizer implements URLNormalizer {

    private Configuration conf;

    private static final Logger LOG = LoggerFactory.getLogger(HostURLNormalizer.class);

    private static String attributeFile = null;
    private String hostsFile = null;
    private static final HashMap<String, String> hostsMap = new HashMap<String, String>();

    public HostURLNormalizer() {
    }

    public HostURLNormalizer(String hostsFile) {
        this.hostsFile = hostsFile;
    }

    private synchronized void readConfiguration(Reader configReader) throws IOException {
        if (hostsMap.size() > 0) {
            return;
        }

        BufferedReader reader = new BufferedReader(configReader);
        String line, host, target;
        int delimiterIndex;

        while ((line = reader.readLine()) != null) {
            if (StringUtils.isNotBlank(line) && !line.startsWith("#")) {
                line.trim();
                delimiterIndex = line.indexOf(" ");

                host = line.substring(0, delimiterIndex);
                target = line.substring(delimiterIndex + 1);
                hostsMap.put(host, target);
            }
        }
    }

    public Configuration getConf() {
        return conf;
    }

    public void setConf(Configuration conf) {
        this.conf = conf;

        // get the extensions for domain urlfilter
        String pluginName = "urlnormalizer-host";
        Extension[] extensions = PluginRepository.get(conf).getExtensionPoint(URLNormalizer.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;
            }
        }

        // handle blank non empty input
        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);
            }
        }

        // domain file and attribute "file" take precedence if defined
        String file = conf.get("urlnormalizer.hosts.file");
        String stringRules = conf.get("urlnormalizer.hosts.rules");
        if (hostsFile != null) {
            file = hostsFile;
        } else if (attributeFile != null) {
            file = attributeFile;
        }
        Reader reader = null;
        if (stringRules != null) { // takes precedence over files
            reader = new StringReader(stringRules);
        } else {
            reader = conf.getConfResourceAsReader(file);
        }
        try {
            if (reader == null) {
                reader = new FileReader(file);
            }
            readConfiguration(reader);
        } catch (IOException e) {
            LOG.error(org.apache.hadoop.util.StringUtils.stringifyException(e));
        }
    }

    public String normalize(String urlString, String scope) throws MalformedURLException {
        String host = new URL(urlString).getHost();

        // Test static hosts
        if (hostsMap.containsKey(host)) {
            return replaceHost(urlString, host, hostsMap.get(host));
        }

        // Test for wildcard in reverse order
        String[] hostParts = host.split("\\.");

        // Use a buffer for our host parts
        StringBuilder hostBuffer = new StringBuilder();

        // This is our temp buffer keeping host parts with a wildcard
        String wildCardHost = new String();

        // Add the tld to the buffer
        hostBuffer.append(hostParts[hostParts.length - 1]);

        for (int i = hostParts.length - 2; i > 0; i--) {
            // Prepend another sub domain
            hostBuffer.insert(0, hostParts[i] + ".");

            // Make a wildcarded sub domain
            wildCardHost = "*." + hostBuffer.toString();

            // Check if this wildcard sub domain exists
            if (hostsMap.containsKey(wildCardHost)) {
                // Replace the original input host with the wildard replaced
                return replaceHost(urlString, host, hostsMap.get(wildCardHost));
            }
        }

        return urlString;
    }

    protected String replaceHost(String urlString, String host, String target) {
        int hostIndex = urlString.indexOf(host);

        StringBuilder buffer = new StringBuilder();

        buffer.append(urlString.substring(0, hostIndex));
        buffer.append(target);
        buffer.append(urlString.substring(hostIndex + host.length()));

        return buffer.toString();
    }

}