crawler4j源码学习(2)：Ziroom租房网房源信息采集爬虫

crawler4j是用Java实现的开源网络爬虫。提供了简单易用的接口，可以在几分钟内创建一个多线程网络爬虫。下面实例结合jsoup解析网页，javacsv存储采集数据；采集自如ziroom租房网（http://sz.ziroom.com/z/nl/）的出租房信息。

所有的过程仅需两步完成：

第一步：开发Ziroom采集核心部分代码：

/**
 * @date 2016年8月20日 下午6:13:24
 * @version
 * @since JDK 1.8
 */
public class ZiroomCrawler extends WebCrawler {

    /** 爬取匹配原则 */
    private final static Pattern FILTERS = Pattern.compile(".*(\\.(css|js|bmp|gif|jpe?g|ico"
            + "|png|tiff?|mid|mp2|mp3|mp4" + "|wav|avi|mov|mpeg|ram|m4v|pdf" + "|rm|smil|wmv|swf|wma|zip|rar|gz))$");
    /** 爬取数据保存文件路径 */
    private final static String DATA_PATH = "data/crawl/ziroom.csv";
    /** 爬取link文件路径 */
    private final static String LINK_PATH = "data/crawl/link.csv";
    // private static final Logger logger =
    // LoggerFactory.getLogger(ZiroomCrawler.class);

    private final static String URL_PREFIX = "http://sh.ziroom.com/z/nl/";

    private final File fLinks;
    private final File fDatas;

    private CsvWriter csvLinks;
    private CsvWriter csvDatas;

    /**
     * You should implement this function to specify whether the given url
     * should be crawled or not (based on your crawling logic).
     */
    ZiroomCrawlStat myCrawlStat;

    public ZiroomCrawler() throws IOException {
        myCrawlStat = new ZiroomCrawlStat();
        fLinks = new File(DATA_PATH);
        fDatas = new File(LINK_PATH);
        if (fLinks.isFile()) {
            fLinks.delete();
        }
        if (fDatas.isFile()) {
            fDatas.delete();
        }
        csvDatas = new CsvWriter(new FileWriter(fDatas, true), ',');
        csvDatas.write("请求路径");
        csvDatas.endRecord();
        csvDatas.close();
        csvLinks = new CsvWriter(new FileWriter(fLinks, true), ',');
        csvLinks.write("图片");
        csvLinks.write("价格");
        csvLinks.write("地址");
        csvLinks.write("说明");
        csvLinks.endRecord();
        csvLinks.close();
    }

    public void dumpMyData() {
        final int id = getMyId();
        // You can configure the log to output to file
        logger.info("Crawler {} > Processed Pages: {}", id, myCrawlStat.getTotalProcessedPages());
        logger.info("Crawler {} > Total Links Found: {}", id, myCrawlStat.getTotalLinks());
        logger.info("Crawler {} > Total Text Size: {}", id, myCrawlStat.getTotalTextSize());
    }

    @Override
    public Object getMyLocalData() {
        return myCrawlStat;
    }

    @Override
    public void onBeforeExit() {
        dumpMyData();
    }

    /*
     * 这个方法决定了要抓取的URL及其内容，例子中只允许抓取“http://sh.ziroom.com/z/nl/”这个域的页面,
     * 不允许.css、.js和多媒体等文件
     *
     * @see edu.uci.ics.crawler4j.crawler.WebCrawler#shouldVisit(edu.uci.ics.
     * crawler4j.crawler.Page, edu.uci.ics.crawler4j.url.WebURL)
     */
    @Override
    public boolean shouldVisit(Page referringPage, WebURL url) {
        final String href = url.getURL().toLowerCase();

        if (FILTERS.matcher(href).matches() || !href.startsWith(URL_PREFIX)) {
            return false;
        }
        return true;
    }

    /*
     * 当URL下载完成会调用这个方法。你可以轻松获取下载页面的url, 文本, 链接, html,和唯一id等内容。
     *
     * @see
     * edu.uci.ics.crawler4j.crawler.WebCrawler#visit(edu.uci.ics.crawler4j.
     * crawler.Page)
     */
    @Override
    public void visit(Page page) {
        final String url = page.getWebURL().getURL();
        logger.info("爬取路径：" + url);
        myCrawlStat.incProcessedPages();
        if (page.getParseData() instanceof HtmlParseData) {
            final HtmlParseData htmlParseData = (HtmlParseData) page.getParseData();
            final Set<WebURL> links = htmlParseData.getOutgoingUrls();
            try {
                linkToCsv(links);
            } catch (final IOException e2) {
                // TODO Auto-generated catch block
                e2.printStackTrace();
            }
            myCrawlStat.incTotalLinks(links.size());
            try {
                myCrawlStat.incTotalTextSize(htmlParseData.getText().getBytes("UTF-8").length);
            } catch (final UnsupportedEncodingException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            final String html = htmlParseData.getHtml();

            final Document doc = Jsoup.parse(html);

            final Elements contents = doc.select("li[class=clearfix]");

            for (final Element c : contents) {
                // 图片
                final String img = c.select(".img img").first().attr("src");
                logger.debug("图片：" + img);

                // 地址
                final Element txt = c.select("div[class=txt]").first();
                final String arr1 = txt.select("h3 a").first().text();
                final String arr2 = txt.select("h4 a").first().text();
                final String arr3 = txt.select("div[class=detail]").first().text();

                final String arr = arr1.concat(arr1 + ",").concat(arr2 + ",").concat(arr3);
                logger.debug("地址：" + arr);
                // 说明
                final String rank = txt.select("p").first().text();
                logger.debug("说明：" + rank);

                // 价格
                final String pirce = c.select("p[class=price]").first().text();

                try {
                    csvLinks = new CsvWriter(new FileWriter(fLinks, true), ',');
                    csvLinks.write(img);
                    csvLinks.write(pirce);
                    csvLinks.write(arr);
                    csvLinks.write(rank);
                    csvLinks.endRecord();
                    csvLinks.flush();
                    csvLinks.close();
                } catch (final IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void linkToCsv(Set<WebURL> links) throws IOException {
        csvDatas = new CsvWriter(new FileWriter(fDatas, true), ',');
        for (final WebURL webURL : links) {
            csvDatas.write(webURL.getURL());
        }
        csvDatas.flush();
        csvDatas.endRecord();
        csvDatas.close();
    }
}

第二步：开发Ziroom采集控制部分代码：

/**
 * @date 2016年8月20日 下午6:15:01
 * @version
 * @since JDK 1.8
 */
public class ZiroomController {

    public static void main(String[] args) {

        final String crawlStorageFolder = "data/crawl/root";
        final int numberOfCrawlers = 3;

        final CrawlConfig config = new CrawlConfig();
        config.setCrawlStorageFolder(crawlStorageFolder);
        config.setPolitenessDelay(1000);
        config.setIncludeBinaryContentInCrawling(false);
        config.setMaxPagesToFetch(50);

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

            controller.addSeed("http://sh.ziroom.com/z/nl/");

            controller.start(ZiroomCrawler.class, numberOfCrawlers);

            final List<Object> crawlersLocalData = controller.getCrawlersLocalData();
            long totalLinks = 0;
            long totalTextSize = 0;
            int totalProcessedPages = 0;
            for (final Object localData : crawlersLocalData) {
                final ZiroomCrawlStat stat = (ZiroomCrawlStat) localData;
                totalLinks += stat.getTotalLinks();
                totalTextSize += stat.getTotalTextSize();
                totalProcessedPages += stat.getTotalProcessedPages();
            }

            System.out.println("Aggregated Statistics:");
            System.out.println("\tProcessed Pages: {}" + totalProcessedPages);
            System.out.println("\tTotal Links found: {}" + totalLinks);
            System.out.println("\tTotal Text Size: {}" + totalTextSize);
        } catch (final Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

第三步：开发Ziroom采集状态搜集代码：

/**
 * @date 2016年8月20日 下午6:14:13
 * @version
 * @since JDK 1.8
 */
public class ZiroomCrawlStat {
    private long totalLinks;
    private int totalProcessedPages;
    private long totalTextSize;

    public long getTotalLinks() {
        return totalLinks;
    }

    public int getTotalProcessedPages() {
        return totalProcessedPages;
    }

    public long getTotalTextSize() {
        return totalTextSize;
    }

    public void incProcessedPages() {
        this.totalProcessedPages++;
    }

    public void incTotalLinks(int count) {
        this.totalLinks += count;
    }

    public void incTotalTextSize(int count) {
        this.totalTextSize += count;
    }

    public void setTotalLinks(long totalLinks) {
        this.totalLinks = totalLinks;
    }

    public void setTotalProcessedPages(int totalProcessedPages) {
        this.totalProcessedPages = totalProcessedPages;
    }

    public void setTotalTextSize(long totalTextSize) {
        this.totalTextSize = totalTextSize;
    }
}

Ziroom采集数据展示：