网络爬虫2：使用crawler4j爬取网络内容

import java.util.Set;
import java.util.regex.Pattern;

import edu.uci.ics.crawler4j.crawler.CrawlConfig;
import edu.uci.ics.crawler4j.crawler.CrawlController;
import edu.uci.ics.crawler4j.crawler.Page;
import edu.uci.ics.crawler4j.crawler.WebCrawler;
import edu.uci.ics.crawler4j.fetcher.PageFetcher;
import edu.uci.ics.crawler4j.parser.HtmlParseData;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtConfig;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtServer;
import edu.uci.ics.crawler4j.url.WebURL;

public class MyCrawler extends WebCrawler {
    // 三要素：
    // _访问谁？
    // _怎么访？
    // _访上了怎么处置？
    private static final String C_URL = "http://www.ximalaya.com";

    @Override
    public boolean shouldVisit(Page referringPage, WebURL url) {
        String href = url.getURL().toLowerCase();
        // 不匹配：MP3|jpg|png结尾的资源
        Pattern p = Pattern.compile(".*(\\.(MP3|jpg|png))$");
        return !p.matcher(href).matches() && href.startsWith(C_URL);
    }

    @Override
    public void visit(Page page) {

        String url = page.getWebURL().getURL();
        String parentUrl = page.getWebURL().getParentUrl();
        String anchor = page.getWebURL().getAnchor();
        System.out.println("********************************");
        System.out.println("URL        :" + url);
        System.out.println("Parent page:" + parentUrl);
        System.out.println("Anchor text:" + anchor);

        logger.info("URL: {}", url);
        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();
            System.out.println("--------------------------");
            System.out.println("Text length: " + text.length());
            System.out.println("Html length: " + html.length());
            System.out.println("Number of outgoing links: " + links.size());
        }
    }

    public static void main(String[] args) throws Exception {
        // 源代码例子中，这两位是两只参数
        // 配置个路径，这个路径相当于Temp文件夹，不用先建好，
        String crawlStorageFolder = "/data/crawl/root";
        int numberOfCrawlers = 7;

        CrawlConfig crawlConf = new CrawlConfig();
        crawlConf.setCrawlStorageFolder(crawlStorageFolder);
        PageFetcher pageFetcher = new PageFetcher(crawlConf);

        RobotstxtConfig robotConf = new RobotstxtConfig();
        RobotstxtServer robotServ = new RobotstxtServer(robotConf, pageFetcher);

        // 控制器
        CrawlController c = new CrawlController(crawlConf,
                pageFetcher, robotServ);
        // 添加网址
        c.addSeed(C_URL);

        // 启动爬虫
        c.start(MyCrawler.class, numberOfCrawlers);
    }
}