crawler4j：轻量级多线程网络爬虫实例

crawler4j是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(中文版API)，javacvs 爬取自如租房网（http://sh.ziroom.com/z/nl/）租房信息。

1.maven导入相关包

         <dependency>
             <groupId>edu.uci.ics</groupId>
             <artifactId>crawler4j</artifactId>
             <version>4.2</version>
         </dependency>
         <dependency>
             <groupId>org.jsoup</groupId>
             <artifactId>jsoup</artifactId>
             <version>1.8.3</version>
         </dependency>
         <dependency>
             <groupId>net.sourceforge.javacsv</groupId>
             <artifactId>javacsv</artifactId>
             <version>2.0</version>
         </dependency>

2.创建自己的Crawler类 继承 WebCrawler

 public class ZiroomCrawler extends WebCrawler {
     /** 爬取数据保存文件路径 */
     private final static String CSV_PATH = "data/crawl/ziroom.csv";
     /** 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 csv;

     private final File csv2;
     private CsvWriter cw;
     private CsvWriter cw2;

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

     public ZiroomCrawler() throws IOException {
         myCrawlStat = new CrawlStat();
         csv = new File(CSV_PATH);
         csv2 = new File(LINK_PATH);
         if (csv.isFile()) {
             csv.delete();
         }
         if (csv2.isFile()) {
             csv2.delete();
         }
         cw2 = new CsvWriter(new FileWriter(csv2, true), ',');
         cw2.write("请求路径");
         cw2.endRecord();
         cw2.close();
         cw = new CsvWriter(new FileWriter(csv, true), ',');
         cw.write("图片");
         cw.write("价格");
         cw.write("地址");
         cw.write("说明");
         cw.endRecord();
         cw.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();
         System.out.println("-----------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");
                 System.out.println("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);
                 System.out.println("地址：" + arr);
                 // 说明
                 final String rank = txt.select("p").first().text();
                 System.out.println("说明：" + rank);

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

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

     private void linkToCsv(Set<WebURL> links) throws IOException {
         cw2 = new CsvWriter(new FileWriter(csv2, true), ',');
         for (final WebURL webURL : links) {
             cw2.write(webURL.getURL());
         }
         cw2.flush();
         cw2.endRecord();
         cw2.close();

     }

public class CrawlStat {
    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;
    }
}

3.编写运行脚本的类

public class ZiroomController {

    public static void main(String[] args) {
        System.out.println("-------begin:" + new Timestamp(System.currentTimeMillis()));
        final String crawlStorageFolder = "data/crawl/root";
        final int numberOfCrawlers = 7;

        final CrawlConfig config = new CrawlConfig();
        config.setCrawlStorageFolder(crawlStorageFolder);
        config.setPolitenessDelay(1000);
        config.setIncludeBinaryContentInCrawling(false);
        config.setMaxPagesToFetch(50);
        // config.setResumableCrawling(true);
        /*
         * Instantiate the controller for this crawl.
         */
        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);
            /*
             * 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("http://sh.ziroom.com/z/nl/");
            // controller.addSeed("http://www.ziroom.com/z/nl/z3-u2.html/");
            // controller.addSeed("http://www.ics.uci.edu/~welling/");
            // controller.addSeed("http://www.ics.uci.edu/");

            /*
             * 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(ZiroomCrawler.class, numberOfCrawlers);

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

刚开始写博客 仅供参考！请多指教！

开源地址： https://github.com/yasserg/crawler4j