最近学习爬虫，分析了几种主流的爬虫框架，决定使用最原始的两大框架进行练手：
Jsoup&HttpUnit
其中jsoup可以获取静态页面，并解析页面标签，最主要的是，可以采用类似于jquery的语法获取想要的标签元素，例如：
//1.获取url地址的网页html html = Jsoup.connect(url).get(); // 2.jsoup获取新闻<a>标签 Elements newsATags = html.select("div#headLineDefault") .select("ul.FNewMTopLis") .select("li") .select("a");但是，有些网页（例如今日头条）并非是静态页面，而是在首页加载后通过ajax获取新闻内容然后用js渲染到页面上的。对于这种页面，我们需要使用htmlunit来模拟一个浏览器访问该url，即可获取该页面的html字符串。代码如下：
WebClient webClient = new WebClient(BrowserVersion.CHROME); webClient.getOptions().setJavaScriptEnabled(true); webClient.getOptions().setCssEnabled(false); webClient.getOptions().setActiveXNative(false); webClient.getOptions().setCssEnabled(false); webClient.getOptions().setThrowExceptionOnScriptError(false); webClient.getOptions().setThrowExceptionOnFailingStatusCode(false); webClient.getOptions().setTimeout(10000); HtmlPage htmlPage = null; try { htmlPage = webClient.getPage(url); webClient.waitForBackgroundJavaScript(10000); String htmlString = htmlPage.asXml(); return Jsoup.parse(htmlString); } finally { webClient.close(); }这三家的页面都是静态的，因此代码都差不多，只要分析页面标签找到对应的元素，提取出想要的内容即可。
爬虫基本步骤为以下四步：
（1）获取首页
（2）使用jsoup获取新闻<a>标签
（3）从<a>标签中抽取基本信息，封装成News对象
（4）根据新闻url访问新闻页面，获取新闻内容、图片等
一个接口，接口有一个抽象方法pullNews用于拉新闻，有一个默认方法用于获取新闻首页：
public interface NewsPuller { void pullNews(); // url:即新闻首页url // useHtmlUnit:是否使用htmlunit default Document getHtmlFromUrl(String url, boolean useHtmlUnit) throws Exception { if (!useHtmlUnit) { return Jsoup.connect(url) //模拟火狐浏览器 .userAgent("Mozilla/4.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)") .get(); } else { WebClient webClient = new WebClient(BrowserVersion.CHROME); webClient.getOptions().setJavaScriptEnabled(true); webClient.getOptions().setCssEnabled(false); webClient.getOptions().setActiveXNative(false); webClient.getOptions().setCssEnabled(false); webClient.getOptions().setThrowExceptionOnScriptError(false); webClient.getOptions().setThrowExceptionOnFailingStatusCode(false); webClient.getOptions().setTimeout(10000); HtmlPage htmlPage = null; try { htmlPage = webClient.getPage(url); webClient.waitForBackgroundJavaScript(10000); String htmlString = htmlPage.asXml(); return Jsoup.parse(htmlString); } finally { webClient.close(); } } } }@Component("sohuNewsPuller") public class SohuNewsPuller implements NewsPuller { private static final Logger logger = LoggerFactory.getLogger(SohuNewsPuller.class); @Value("${news.sohu.url}") private String url; @Autowired private NewsService newsService; @Override public void pullNews() { logger.info("开始拉取搜狐新闻！"); // 1.获取首页 Document html= null; try { html = getHtmlFromUrl(url, false); } catch (Exception e) { logger.error("==============获取搜狐首页失败: {}=============", url); e.printStackTrace(); return; } // 2.jsoup获取新闻<a>标签 Elements newsATags = html.select("div.focus-news") .select("div.list16") .select("li") .select("a"); // 3.从<a>标签中抽取基本信息，封装成news HashSet<News> newsSet = new HashSet<>(); for (Element a : newsATags) { String url = a.attr("href"); String title = a.attr("title"); News n = new News(); n.setSource("搜狐"); n.setUrl(url); n.setTitle(title); n.setCreateDate(new Date()); newsSet.add(n); } // 4.根据新闻url访问新闻，获取新闻内容 newsSet.forEach(news -> { logger.info("开始抽取搜狐新闻内容：{}", news.getUrl()); Document newsHtml = null; try { newsHtml = getHtmlFromUrl(news.getUrl(), false); Element newsContent = newsHtml.select("div#article-container") .select("div.main") .select("div.text") .first(); String title = newsContent.select("div.text-title").select("h1").text(); String content = newsContent.select("article.article").first().toString(); String image = NewsUtils.getImageFromContent(content); news.setTitle(title); news.setContent(content); news.setImage(image); newsService.saveNews(news); logger.info("抽取搜狐新闻《{}》成功！", news.getTitle()); } catch (Exception e) { logger.error("新闻抽取失败:{}", news.getUrl()); e.printStackTrace(); } }); } }@Component("ifengNewsPuller") public class IfengNewsPuller implements NewsPuller { private static final Logger logger = LoggerFactory.getLogger(IfengNewsPuller.class); @Value("${news.ifeng.url}") private String url; @Autowired private NewsService newsService; @Override public void pullNews() { logger.info("开始拉取凤凰新闻！"); // 1.获取首页 Document html= null; try { html = getHtmlFromUrl(url, false); } catch (Exception e) { logger.error("==============获取凤凰首页失败: {} =============", url); e.printStackTrace(); return; } // 2.jsoup获取新闻<a>标签 Elements newsATags = html.select("div#headLineDefault") .select("ul.FNewMTopLis") .select("li") .select("a"); // 3.从<a>标签中抽取基本信息，封装成news HashSet<News> newsSet = new HashSet<>(); for (Element a : newsATags) { String url = a.attr("href"); String title = a.text(); News n = new News(); n.setSource("凤凰"); n.setUrl(url); n.setTitle(title); n.setCreateDate(new Date()); newsSet.add(n); } // 4.根据新闻url访问新闻，获取新闻内容 newsSet.parallelStream().forEach(news -> { logger.info("开始抽取凤凰新闻《{}》内容：{}", news.getTitle(), news.getUrl()); Document newsHtml = null; try { newsHtml = getHtmlFromUrl(news.getUrl(), false); Elements contentElement = newsHtml.select("div#main_content"); if (contentElement.isEmpty()) { contentElement = newsHtml.select("div#yc_con_txt"); } if (contentElement.isEmpty()) return; String content = contentElement.toString(); String image = NewsUtils.getImageFromContent(content); news.setContent(content); news.setImage(image); newsService.saveNews(news); logger.info("抽取凤凰新闻《{}》成功！", news.getTitle()); } catch (Exception e) { logger.error("凤凰新闻抽取失败:{}", news.getUrl()); e.printStackTrace(); } }); logger.info("凤凰新闻抽取完成！"); } }@Component("netEasyNewsPuller") public class NetEasyNewsPuller implements NewsPuller { private static final Logger logger = LoggerFactory.getLogger(NetEasyNewsPuller.class); @Value("${news.neteasy.url}") private String url; @Autowired private NewsService newsService; @Override public void pullNews() { logger.info("开始拉取网易热门新闻！"); // 1.获取首页 Document html= null; try { html = getHtmlFromUrl(url, false); } catch (Exception e) { logger.error("==============获取网易新闻首页失败: {}=============", url); e.printStackTrace(); return; } // 2.jsoup获取指定标签 Elements newsA = html.select("div#whole") .next("div.area-half.left") .select("div.tabContents") .first() .select("tbody > tr") .select("a[href~=^http://news.163.com.*]"); // 3.从标签中抽取信息，封装成news HashSet<News> newsSet = new HashSet<>(); newsA.forEach(a -> { String url = a.attr("href"); News n = new News(); n.setSource("网易"); n.setUrl(url); n.setCreateDate(new Date()); newsSet.add(n); }); // 4.根据url访问新闻，获取新闻内容 newsSet.forEach(news -> { logger.info("开始抽取新闻内容：{}", news.getUrl()); Document newsHtml = null; try { newsHtml = getHtmlFromUrl(news.getUrl(), false); Elements newsContent = newsHtml.select("div#endText"); Elements titleP = newsContent.select("p.otitle"); String title = titleP.text(); title = title.substring(5, title.length() - 1); String image = NewsUtils.getImageFromContent(newsContent.toString()); news.setTitle(title); news.setContent(newsContent.toString()); news.setImage(image); newsService.saveNews(news); logger.info("抽取网易新闻《{}》成功！", news.getTitle()); } catch (Exception e) { logger.error("新闻抽取失败:{}", news.getUrl()); e.printStackTrace(); } }); logger.info("网易新闻拉取完成！"); } }由于今日头条页面中的新闻是通过ajax获取后加载的，因此需要使用httpunit进行抓取。
主要代码如下：
@Component("toutiaoNewsPuller") public class ToutiaoNewsPuller implements NewsPuller { private static final Logger logger = LoggerFactory.getLogger(ToutiaoNewsPuller.class); private static final String TOUTIAO_URL = "https://www.toutiao.com"; @Autowired private NewsService newsService; @Value("${news.toutiao.url}") private String url; @Override public void pullNews() { logger.info("开始拉取今日头条热门新闻！"); // 1.load html from url Document html = null; try { html = getHtmlFromUrl(url, true); } catch (Exception e) { logger.error("获取今日头条主页失败！"); e.printStackTrace(); return; } // 2.parse the html to news information and load into POJO Map<String, News> newsMap = new HashMap<>(); for (Element a : html.select("a[href~=/group/.*]:not(.comment)")) { logger.info("标签a: \n{}", a); String href = TOUTIAO_URL + a.attr("href"); String title = StringUtils.isNotBlank(a.select("p").text()) ? a.select("p").text() : a.text(); String image = a.select("img").attr("src"); News news = newsMap.get(href); if (news == null) { News n = new News(); n.setSource("今日头条"); n.setUrl(href); n.setCreateDate(new Date()); n.setImage(image); n.setTitle(title); newsMap.put(href, n); } else { if (a.hasClass("img-wrap")) { news.setImage(image); } else if (a.hasClass("title")) { news.setTitle(title); } } } logger.info("今日头条新闻标题拉取完成!"); logger.info("开始拉取新闻内容..."); newsMap.values().parallelStream().forEach(news -> { logger.info("===================={}====================", news.getTitle()); Document contentHtml = null; try { contentHtml = getHtmlFromUrl(news.getUrl(), true); } catch (Exception e) { logger.error("获取新闻《{}》内容失败！", news.getTitle()); return; } Elements scripts = contentHtml.getElementsByTag("script"); scripts.forEach(script -> { String regex = "articleInfo: \\{\\s*[\\n\\r]*\\s*title: '.*',\\s*[\\n\\r]*\\s*content: '(.*)',"; Pattern pattern = Pattern.compile(regex); Matcher matcher = pattern.matcher(script.toString()); if (matcher.find()) { String content = matcher.group(1) .replace("<", "<") .replace(">", ">") .replace(""", "\"") .replace("=", "="); logger.info("content: {}", content); news.setContent(content); } }); }); newsMap.values() .stream() .filter(news -> StringUtils.isNotBlank(news.getContent()) && !news.getContent().equals("null")) .forEach(newsService::saveNews); logger.info("今日头条新闻内容拉取完成!"); } }拉取结果： 