BasicCrawler.java Source code

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Here is the source code for BasicCrawler.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.
 */

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import java.util.Set;
import java.util.regex.Pattern;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.http.Header;

import edu.uci.ics.crawler4j.crawler.Page;
import edu.uci.ics.crawler4j.crawler.WebCrawler;
import edu.uci.ics.crawler4j.parser.HtmlParseData;
import edu.uci.ics.crawler4j.url.WebURL;

/**
 * @author Yasser Ganjisaffar
 */
public class BasicCrawler extends WebCrawler {

    private static final Pattern IMAGE_EXTENSIONS = Pattern.compile(".*\\.(bmp|gif|jpg|png)$");
    private static BufferedWriter bw;
    private static FileWriter fw = null;

    /**
     * You should implement this function to specify whether the given url
     * should be crawled or not (based on your crawling logic).
     */
    @Override
    public boolean shouldVisit(Page referringPage, WebURL url) {
        String href = url.getURL().toLowerCase();
        // Ignore the url if it has an extension that matches our defined set of image extensions.
        if (IMAGE_EXTENSIONS.matcher(href).matches()) {
            return false;
        }

        // Only accept the url if it is in the "www.ics.uci.edu" domain and protocol is "http".
        return href.startsWith("http://www.ics.uci.edu/");
    }

    public BasicCrawler() {
        try {
            fw = new FileWriter("src/main/resources/url_map.txt");
            //fw = new FileWriter("src/main/resources/url_map_amazon.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }
        bw = new BufferedWriter(fw);
    }

    /**
     * This function is called when a page is fetched and ready to be processed
     * by your program.
     */
    @Override
    public void visit(Page page) {
        int docid = page.getWebURL().getDocid();
        String url = page.getWebURL().getURL();
        String domain = page.getWebURL().getDomain();
        String path = page.getWebURL().getPath();
        String subDomain = page.getWebURL().getSubDomain();
        String parentUrl = page.getWebURL().getParentUrl();
        String anchor = page.getWebURL().getAnchor();

        logger.debug("Docid: {}", docid);
        logger.info("URL: {}", url);
        logger.debug("Domain: '{}'", domain);
        logger.debug("Sub-domain: '{}'", subDomain);
        logger.debug("Path: '{}'", path);
        logger.debug("Parent page: {}", parentUrl);
        logger.debug("Anchor text: {}", anchor);

        if (page.getParseData() instanceof HtmlParseData) {
            HtmlParseData htmlParseData = (HtmlParseData) page.getParseData();
            String text = htmlParseData.getText();
            String html = htmlParseData.getHtml();
            Set<WebURL> links = htmlParseData.getOutgoingUrls();
            writeToFile(url, links);

            logger.debug("Text length: {}", text.length());
            logger.debug("Html length: {}", html.length());
            logger.debug("Number of outgoing links: {}", links.size());
        }

        Header[] responseHeaders = page.getFetchResponseHeaders();
        if (responseHeaders != null) {
            logger.debug("Response headers:");
            for (Header header : responseHeaders) {
                logger.debug("\t{}: {}", header.getName(), header.getValue());
            }
        }

        logger.debug("=============");
    }

    private void writeToFile(String url, Set<WebURL> links) {
        Configuration conf = new Configuration();
        FileSystem fs1;
        try {
            //         fs1 = FileSystem.get(
            //               URI.create("src/main/resources/url_map.txt"), conf);
            //         OutputStream file3 = fs1.create(new Path("src/main/resources/url_map.txt"));
            bw.write(url + "," + links.toString() + "\n");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}