java - 增加爬虫的线程数

Question

This is the code taken from http://code.google.com/p/crawler4j/ and the name of this file is MyCrawler.java


public class MyCrawler extends WebCrawler {

        Pattern filters = Pattern.compile(".*(\\.(css|js|bmp|gif|jpe?g"
                + "|png|tiff?|mid|mp2|mp3|mp4"
                + "|wav|avi|mov|mpeg|ram|m4v|pdf"
                + "|rm|smil|wmv|swf|wma|zip|rar|gz))$");

        /*
         * You should implement this function to specify
         * whether the given URL should be visited or not.
         */
        public boolean shouldVisit(WebURL url) {
                String href = url.getURL().toLowerCase();
                if (filters.matcher(href).matches()) {
                        return false;
                }
                if (href.startsWith("http://www.xyz.us.edu/")) {
                        return true;
                }
                return false;
        }

        /*
         * This function is called when a page is fetched
         * and ready to be processed by your program
         */
        public void visit(Page page) {
                int docid = page.getWebURL().getDocid();
                String url = page.getWebURL().getURL();         
                String text = page.getText();
                List<WebURL> links = page.getURLs();            
        }
}

这是调用 MyCrawler 的 Controller.java 代码..

public class Controller {
        public static void main(String[] args) throws Exception {
                CrawlController controller = new CrawlController("/data/crawl/root");
                controller.addSeed("http://www.xyz.us.edu/");
                controller.start(MyCrawler.class, 10);  
        }
}

所以我只是想确定这行在controller.java文件中意味着什么

controller.start(MyCrawler.class, 10);

这里 10 的含义是什么..如果我们将这个 10 增加到 20 那么会产生什么效果...任何建议将不胜感激...

Answer 1

This网站显示了 CrawlController 的源代码。

从 10 增加到 20 会增加爬网程序的数量(每个爬网程序都在自己的线程中) - 研究该代码将告诉您这会产生什么影响。