java - 使用crawler4j在类之间传输一个对象

Question

我是一个简单的网络爬虫，它是使用crawler4j的构建 block 构建的。我试图在爬虫爬行时构建一个字典，然后在构建和解析文本时将其传递给我的主( Controller )。由于我的 MyCrawler 对象不是在我的主类中创建的(使用 MyCrawler.class 作为第一个参数)，我该如何执行此操作？另外，我无法更改controller.start方法。我希望能够在爬虫完成后使用爬虫中创建的字典。

我能想到的最好方法是让controller.start采用预定义和创建的MyCrawler对象，但据我所知，没有办法做到这一点。

下面是我的代码。非常感谢您的帮助!

爬虫:

public class MyCrawler extends WebCrawler
{
    private final static Pattern FILTERS = Pattern.compile(".*(\\.(css|js|gif|jpg|png|mp3|mp3|zip|gz))$");
    public ArrayList<String> dictionary = new ArrayList<String>();

    @Override public boolean shouldVisit(Page referringPage, WebURL url)
    {
        String href = url.getURL().toLowerCase();
        return !FILTERS.matcher(href).matches()
                && href.startsWith("http://lyle.smu.edu/~fmoore"));
    }

    @Override public void visit(Page page)
    {
        String url = page.getWebURL().getURL();
        System.out.println("URL: " + url);
        if(page.getParseData() instanceof HtmlParseData)
        {
            HtmlParseData h = (HtmlParseData)page.getParseData();
            String text = h.getText();

            String[] words = text.split(" ");
            for(int i = 0;i < words.length;i++)
            {
                if(!words[i].equals("") || !words[i].equals(null) || !words[i].equals("\n"))
                    dictionary.add(words[i]);
            }

            String html = h.getHtml();
            Set<WebURL> links = h.getOutgoingUrls();

            System.out.println("Text length: " + text.length());
            System.out.println("Html length: " + html.length());
            System.out.println("Number of outgoing links: " + links.size());
            System.out.println(text);
        }
    }
}

Controller :

public class Controller 
{
    public ArrayList<String> dictionary = new ArrayList<String>();

    public static void main(String[] args) throws Exception
    {
        int numberOfCrawlers = 1;
        String crawlStorageFolder = "/data/crawl/root";

        CrawlConfig c = new CrawlConfig();
        c.setCrawlStorageFolder(crawlStorageFolder);
        c.setMaxDepthOfCrawling(-1);    //Unlimited Depth
        c.setMaxPagesToFetch(-1);       //Unlimited Pages
        c.setPolitenessDelay(200);      //Politeness Delay

        PageFetcher pf = new PageFetcher(c);
        RobotstxtConfig robots = new RobotstxtConfig();
        RobotstxtServer rs = new RobotstxtServer(robots, pf);
        CrawlController controller = new CrawlController(c, pf, rs);

        controller.addSeed("http://lyle.smu.edu/~fmoore");

        controller.start(MyCrawler.class, numberOfCrawlers);        

        controller.shutdown();
        controller.waitUntilFinish();
    }
}

Answer 1

让 WebCrawlerFactory 创建您的 MyCrawler 对象。这应该可以解决问题(至少从 4.2 版本开始)。但是，您的字典应该支持并发访问(简单的ArrayList不支持!)

// use a factory, instead of supplying the crawler type to pass the dictionary
controller.start(new WebCrawlerFactory<MyCrawler>() {
    @Override
    public MyCrawler newInstance() throws Exception {
        return new MyCrawler(dictionary);
    }
}, numberOfCrawlers);