基于Crawler4j + jsoup实现爬虫 Java相关

爬虫框架分类 1. 分布式爬虫
Nutch
2. Java单机爬虫
Crawler4j、WebMagic、WebCollector
3. 非Java单机爬虫
Scrapy

开发思路根据业务需求选择合适的爬虫框架
根据网站规则及业务需求抽取数据，保存到中间库
数据清洗/格式化，保存到目标库

基于Crawler4j + jsoup实现爬虫用Crawler4j构建多线程的web爬虫来抓取页面内容。Crawler4j的使用分为两个步骤：
(1) 实现一个继承自WebCrawler的爬虫类
需要覆盖两个主要方法：
shouldVisit：这个方法决定了要抓取的URL及其内容。
visit：当URL下载完成会调用这个方法。使用jsoup解析HTML，可以采用jQuery选择器的语法。
(2) 通过CrawController调用实现的爬虫类。
指定抓取的种子（seed）、中间数据存储的文件夹、并发线程的数目等信息，实现控制器类。

示例代码 pom.xml中依赖包设置

edu.uci.ics crawler4j 4.2 org.jsoup jsoup 1.10.1

代码

(1) 爬虫类

public class MyCrawler extends WebCrawler { private final static Pattern FILTERS = Pattern.compile(".*(\\.(css|js|gif|jpg" + "|png|mp3|mp3|zip|gz))$"); /** * This method receives two parameters. The first parameter is the page * in which we have discovered this new url and the second parameter is * the new url. You should implement this function to specify whether * the given url should be crawled or not (based on your crawling logic). * In this example, we are instructing the crawler to ignore urls that * have css, js, git, ... extensions and to only accept urls that start * with "http://www.ics.uci.edu/". In this case, we didn't need the * referringPage parameter to make the decision. */ @Override public boolean shouldVisit(Page referringPage, WebURL url) { String href = https://www.it610.com/article/url.getURL().toLowerCase(); return !FILTERS.matcher(href).matches() && href.startsWith("http://www.ics.uci.edu/"); } /** * This function is called when a page is fetched and ready * to be processed by your program. */ @Override public void visit(Page page) { String url = page.getWebURL().getURL(); System.out.println("URL: " + url); if (page.getParseData() instanceof HtmlParseData) { HtmlParseData htmlParseData = https://www.it610.com/article/(HtmlParseData) page.getParseData(); String text = htmlParseData.getText(); String html = htmlParseData.getHtml(); Set links = htmlParseData.getOutgoingUrls(); System.out.println("Text length: " + text.length()); System.out.println("Html length: " + html.length()); System.out.println("Number of outgoing links: " + links.size()); } } }

(2) Controller调用

public class Controller { public static void main(String[] args) throws Exception { String crawlStorageFolder = "/data/crawl/root"; int numberOfCrawlers = 7; CrawlConfig config = new CrawlConfig(); config.setCrawlStorageFolder(crawlStorageFolder); /* * Instantiate the controller for this crawl. */ PageFetcher pageFetcher = new PageFetcher(config); RobotstxtConfig robotstxtConfig = new RobotstxtConfig(); RobotstxtServer robotstxtServer = new RobotstxtServer(robotstxtConfig, pageFetcher); CrawlController 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://www.ics.uci.edu/~lopes/"); 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(MyCrawler.class, numberOfCrawlers); } }

【基于Crawler4j + jsoup实现爬虫】