java source code of CrawlerController

package packt.crawlerj4mavenexample;

import edu.uci.ics.crawler4j.crawler.CrawlConfig;
import edu.uci.ics.crawler4j.crawler.CrawlController;
import edu.uci.ics.crawler4j.fetcher.PageFetcher;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtConfig;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtServer;

public class CrawlerController {

  public static void main(String[] args) throws Exception {
    int numberOfCrawlers = 2;
    CrawlConfig config = new CrawlConfig();
    String crawlStorageFolder = "data";
    
    config.setCrawlStorageFolder(crawlStorageFolder);
    config.setPolitenessDelay(500);
    config.setMaxDepthOfCrawling(2);
    config.setMaxPagesToFetch(20);
    config.setIncludeBinaryContentInCrawling(false);

    PageFetcher pageFetcher = new PageFetcher(config);
    RobotstxtConfig robotstxtConfig = new RobotstxtConfig();
    RobotstxtServer robotstxtServer = new RobotstxtServer(robotstxtConfig, pageFetcher);
    CrawlController controller = new CrawlController(config, pageFetcher, robotstxtServer);

    controller.addSeed("https://en.wikipedia.org/wiki/Bishop_Rock,_Isles_of_Scilly");

    controller.start(SampleCrawler.class, numberOfCrawlers);
  }
}