org.apache.nutch.net.urlnormalizer.querystring.QuerystringURLNormalizer.java Source code

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Here is the source code for org.apache.nutch.net.urlnormalizer.querystring.QuerystringURLNormalizer.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.querystring;

import java.lang.invoke.MethodHandles;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.net.URLNormalizer;

/**
 * URL normalizer plugin for normalizing query strings but sorting query string
 * parameters. Not sorting query strings can lead to large amounts of duplicate
 * URL's such as ?a=x&b=y vs b=y&a=x.
 * 
 */
public class QuerystringURLNormalizer implements URLNormalizer {

    private Configuration conf;

    private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());

    public QuerystringURLNormalizer() {
    }

    public Configuration getConf() {
        return conf;
    }

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

    public String normalize(String urlString, String scope) throws MalformedURLException {
        URL url = new URL(urlString);

        String queryString = url.getQuery();

        if (queryString == null) {
            return urlString;
        }

        List<String> queryStringParts = Arrays.asList(queryString.split("&"));
        Collections.sort(queryStringParts);

        StringBuilder sb = new StringBuilder();

        sb.append(url.getProtocol());
        sb.append("://");
        sb.append(url.getHost());
        if (url.getPort() > -1) {
            sb.append(":");
            sb.append(url.getPort());
        }
        sb.append(url.getPath());
        sb.append("?");
        sb.append(StringUtils.join(queryStringParts, "&"));
        if (url.getRef() != null) {
            sb.append("#");
            sb.append(url.getRef());
        }

        return sb.toString();
    }
}