从用户请求的Headers反反爬

  在访问某些网站的时候，网站通常会用判断访问是否带有头文件来鉴别该访问是否为爬虫，用来作为反爬取的一种策略。很多网站都会对Headers的User-Agent进行检测，还有一部分网站会对Referer进行检测（一些资源网站的防盗链就是检测Referer）。针对这种反爬机制，我们可以伪装headers，将浏览器的User-Agent复制到爬虫的Headers中；或者将Referer值修改为目标网站域名或者为上一个请求地址。

分析Chrome的头信息

访问请求头中包含了浏览器以及系统的信息（headers所含信息众多，其中User-Agent就是用户浏览器身份的一种标识，具体可自行查询）、Referer、Cookie。

代码

引入依赖

        <dependency>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
            <version>1.16.1</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>3.3.2</version>
        </dependency>

@SpringBootTest
class CrawlerApplicationTest {

    @Test
    void contextLoads() {
        Set<String> domainResult = new HashSet<>();
        String urlStr = "http://ssssss.com/domain";
        int pageSize = 0;
        try {
            for (int i = 0; i < 194994; i++) {
                String crawlerUrl = "";
                if (i == 0) {
                    crawler(urlStr, domainResult, null);
//                    crawlerUrl = "http://swkong.com/domain/index" + pageSize + ".html";
//                    System.out.println(pageSize);
//                    System.out.println(crawlerUrl);
                } else {
                    String referrerUrl = "";
                    if (i == 1) {
                        referrerUrl = "http://ssssss.com/domain";
                    } else {
                        referrerUrl = "http://ssssss.com/domain/index" + (pageSize - 1) + ".html";
                    }
                    crawlerUrl = "http://ssssss.com/domain/index" + pageSize + ".html";
                    crawler(crawlerUrl, domainResult, referrerUrl);
                    System.out.println(pageSize);
                    pageSize += 1;

                    System.out.println(crawlerUrl);
                    System.out.println(referrerUrl);
                }
                System.out.println("-----------------------------");
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println(domainResult.size());
            System.out.println("catch");
        } finally {
            System.out.println(domainResult.size());
            writeExcel(domainResult);
        }

    }

    public void crawler(String urlStr, Set<String> domainResult, String referrer) throws IOException, InterruptedException {
        Document parse = sendRequest(urlStr, referrer);
        Elements dispdomain = Objects.requireNonNull(parse.getElementById("dispdomain")).getElementsByAttribute("href");
        getDomain(dispdomain, domainResult);
        System.out.println("请求地址：" + urlStr);
        System.out.println("__________________________________________");
//        Elements xpage = Objects.requireNonNull(parse.getElementById("xpage")).getElementsByAttribute("href");
//        System.out.println(xpage);
//        String crawlerUrl = "http://swkong.com" + xpage.get(page).attr("href");
    }

    public void getDomain(Elements elements, Set<String> result) {
        for (int i = 0; i < elements.size(); i++) {
            String attr = elements.get(i).select("a").attr("href");
            if (attr.contains("?q=")) {
                String s = attr.split("q=")[1];
                result.add(s);
            }
        }
        System.out.println(result.size());
    }

    public Document sendRequest(String urlStr, String referrer) throws IOException {
        Map<String, String> cookies = new HashMap<>();
        cookies.put("cargo_keyword", "xxxxxxxxxxxxxxxxx");
        cookies.put("PHPSESSID", "xxxxxxxxxxxxxxxxx");
        cookies.put("language", "zh-cn");
        if (StringUtils.hasText(referrer)) {
            return Jsoup.connect(urlStr)
                    .timeout(5000)
                    .ignoreContentType(true)
                    .userAgent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36")
                    .cookies(cookies)
                    .referrer(referrer)
                    .get();
        }
        return Jsoup.connect(urlStr)
                .timeout(5000)
                .ignoreContentType(true)
                .userAgent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36")
                .cookies(cookies)
                .get();
    }

    public void writeExcel(Set<String> domainResult) {
        List<DomainDto> resultExcel = new ArrayList<>();
        for (String domain : domainResult) {
            DomainDto domainDto = new DomainDto();
            domainDto.setDomainUrl(domain);
            resultExcel.add(domainDto);
        }

        String path = "D:\\" + System.currentTimeMillis() + ".xlsx";
        EasyExcel.write(path, DomainDto.class).sheet("域名").doWrite(resultExcel);
    }