Examples with CrawlController edu.uci.ics.crawler4j.crawler.CrawlController used on opensource projects

Example 11 with CrawlController

use of edu.uci.ics.crawler4j.crawler.CrawlController in project crawler4j by yasserg.

the class BasicCrawlController method main.

public static void main(String[] args) throws Exception {
    CrawlConfig config = new CrawlConfig();
    // Set the folder where intermediate crawl data is stored (e.g. list of urls that are extracted from previously
    // fetched pages and need to be crawled later).
    config.setCrawlStorageFolder("/tmp/crawler4j/");
    // Be polite: Make sure that we don't send more than 1 request per second (1000 milliseconds between requests).
    // Otherwise it may overload the target servers.
    config.setPolitenessDelay(1000);
    // You can set the maximum crawl depth here. The default value is -1 for unlimited depth.
    config.setMaxDepthOfCrawling(2);
    // You can set the maximum number of pages to crawl. The default value is -1 for unlimited number of pages.
    config.setMaxPagesToFetch(1000);
    // Should binary data should also be crawled? example: the contents of pdf, or the metadata of images etc
    config.setIncludeBinaryContentInCrawling(false);
    // Do you need to set a proxy? If so, you can use:
    // config.setProxyHost("proxyserver.example.com");
    // config.setProxyPort(8080);
    // If your proxy also needs authentication:
    // config.setProxyUsername(username); config.getProxyPassword(password);
    // This config parameter can be used to set your crawl to be resumable
    // (meaning that you can resume the crawl from a previously
    // interrupted/crashed crawl). Note: if you enable resuming feature and
    // want to start a fresh crawl, you need to delete the contents of
    // rootFolder manually.
    config.setResumableCrawling(false);
    // Set this to true if you want crawling to stop whenever an unexpected error
    // occurs. You'll probably want this set to true when you first start testing
    // your crawler, and then set to false once you're ready to let the crawler run
    // for a long time.
    config.setHaltOnError(true);
    // Instantiate the controller for this crawl.
    PageFetcher pageFetcher = new PageFetcher(config);
    RobotstxtConfig robotstxtConfig = new RobotstxtConfig();
    RobotstxtServer robotstxtServer = new RobotstxtServer(robotstxtConfig, pageFetcher);
    CrawlController controller = new CrawlController(config, pageFetcher, robotstxtServer);
    // For each crawl, you need to add some seed urls. These are the first
    // URLs that are fetched and then the crawler starts following links
    // which are found in these pages
    controller.addSeed("https://www.ics.uci.edu/");
    controller.addSeed("https://www.ics.uci.edu/~lopes/");
    controller.addSeed("https://www.ics.uci.edu/~welling/");
    // Number of threads to use during crawling. Increasing this typically makes crawling faster. But crawling
    // speed depends on many other factors as well. You can experiment with this to figure out what number of
    // threads works best for you.
    int numberOfCrawlers = 8;
    // To demonstrate an example of how you can pass objects to crawlers, we use an AtomicInteger that crawlers
    // increment whenever they see a url which points to an image.
    AtomicInteger numSeenImages = new AtomicInteger();
    // The factory which creates instances of crawlers.
    CrawlController.WebCrawlerFactory<BasicCrawler> factory = () -> new BasicCrawler(numSeenImages);
    // Start the crawl. This is a blocking operation, meaning that your code
    // will reach the line after this only when crawling is finished.
    controller.start(factory, numberOfCrawlers);
}