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springBoot+webMagic怎么实现网站爬虫

这篇文章主要讲解了springBoot+webMagic怎么实现网站爬虫,内容清晰明了,对此有兴趣的小伙伴可以学习一下,相信大家阅读完之后会有帮助。

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前端时间公司项目需要抓取各类数据,py玩的不6,只好研究Java爬虫方案,做一个总结。

开发环境:

springBoot 2.2.6、jdk1.8。

1、导入依赖


  
   us.codecraft
   webmagic-core
   0.7.3
   






  
  
  
   us.codecraft
   webmagic-extension
   0.7.3
  

  
  
   com.google.guava
   guava
   16.0
  

话不多说,直接上代码。

基础案例

下面代码说明以一个类似列表的页面为例

package com.crawler.project.proTask;

import com.alibaba.fastjson.JSONObject;
import org.springframework.scheduling.annotation.Scheduled;
import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Spider;
import us.codecraft.webmagic.processor.PageProcessor;
import us.codecraft.webmagic.scheduler.BloomFilterDuplicateRemover;
import us.codecraft.webmagic.scheduler.QueueScheduler;
import us.codecraft.webmagic.selector.Selectable;

import java.util.List;

public class TaskProcessor implements PageProcessor {

 /*
 * 此方法为爬虫业务实现
 * */
 @Override
 public void process(Page page) {

  //1、爬虫任务获取到一个page 解析page上的列表
  List list = page.getHtml().css("css selector").nodes();
  if (list.size() > 0){//说明为列表页面、需要解析列表中每个元素的链接,存入待获取page队列中
   for (Selectable selectable : list) {
    //遍历集合,将每个元素链接存入待获取page队列中
    page.addTargetRequest(selectable.links().toString());
   }
   //同时将下一页的url存入队列中
   page.addTargetRequest("下一页的url");
  }else {
   //此时为列表中单个元素对应的详情页
   //在自定义方法中处理详细页,获取需要的数据进行处理。
   handle(page);
  }
 }

 private void handle(Page page) {

  //例如 处理后的数据为一个JSONObject对象
  JSONObject tmp = new JSONObject();

  //将这个tmp交由自定义的TaskPipline类处理,若未自定义Pipline并设置到Spider参数中,框架会默认将tmp打印到控制台。
  page.putField("obj",tmp);
 }

 /*
 * 此方法为配置爬虫过程的一些参数
 * */
 private Site site = Site.me()
   .setCharset("UTF-8")
   .setTimeOut(60 * 1000)
   .setRetrySleepTime(60 * 1000)
   .setCycleRetryTimes(5);
 @Override
 public Site getSite() {
  return site;
 }

 /*
 设置定时任务,执行爬虫任务
 * */
 @Scheduled(initialDelay = 1 * 1000,fixedDelay = 2 * 1000)
 public void process(){
  System.out.println("开始执行爬虫抓取任务");
  Spider.create(new TaskProcessor())//注意这里的类名要和当前类名对应
    .addUrl("起始页url")
    .addPipeline(new TaskPipeline()) //此处课自定义 数据处理类 (在handle()方法中有);
    .setScheduler(new QueueScheduler().setDuplicateRemover(new BloomFilterDuplicateRemover(100000)))
    .thread(3)//此处设置线程数量(不宜过多,最好和列表页中列表元素数量一致)
    .run();
 }
}
package com.crawler.project.proTask;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import us.codecraft.webmagic.ResultItems;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.pipeline.Pipeline;

public class TaskPipeline implements Pipeline {
 @Override
 public void process(ResultItems resultItems, Task task) {
  if (resultItems.getAll() .size() > 0){
   Object obj = resultItems.getAll().get("obj");
   JSONObject jsonObject = JSON.parseObject(obj.toString());
   //获取到JSONObject对象下面可进行自定义的业务处理。
  }
 }
}

特殊情况一

需根据链接下载图片或文件

eg:在上面说到的详情页中含有iframe。

1、首先获取iframe的src

//获得iframe的src (这里要注意获得的src是绝对路径还是相对路径,相对路径需要拼接主站点url)
String src = html.css("css selector", "src").toString();

//采用jsoup解析
Document document = Jsoup.parse(new URL(src),1000);
//获得需要的元素
Element ele = document.select("css selector").last();
//获取需要下载的文件的链接
String downUrl = ele.attr("href");
//根据链接下载文件 返回一个文件的名称
String fileName = downloadFile(downUrl);
//通过url下载文件
public String downloadFile(String fileUrl) throws FileNotFoundException{
 try{
   URL httpUrl = new URL(fileUrl);
   String fileName = UUID.randomUUID().toString() + ".mp3";
   File file = new File(this.STATIC_FILEPATH + fileName);
   System.out.println("============保存文件方法被调用===============");
   FileUtils.copyURLToFile(httpUrl,file);
   return fileName;
  }catch (Exception e){
   e.printStackTrace();
   return null;
  }
}

特殊情况二

有些https站点 无法直接使用WebMagic默认的下载器下载,此时我们可以根据站点ssl类型修改下载器。

在项目中创建一个包用于存放自定义(修改)的下载器类

(!!!摘自webMagic框架中HttpClientDownloader,基于此类修改!!!)

/*
此方法中需要传入一个自定义的生成器(HttpClientGenerator)
*/

package com.crawler.project.spider_download;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.util.EntityUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.downloader.AbstractDownloader;
import us.codecraft.webmagic.downloader.HttpClientRequestContext;
import us.codecraft.webmagic.downloader.HttpUriRequestConverter;
import us.codecraft.webmagic.proxy.Proxy;
import us.codecraft.webmagic.proxy.ProxyProvider;
import us.codecraft.webmagic.selector.PlainText;
import us.codecraft.webmagic.utils.CharsetUtils;
import us.codecraft.webmagic.utils.HttpClientUtils;

import java.io.IOException;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;


/**
 * The http downloader based on HttpClient.
 *
 * @author code4crafter@gmail.com 
* @since 0.1.0 */ public class HttpClientDownloader extends AbstractDownloader { private Logger logger = LoggerFactory.getLogger(getClass()); private final Map httpClients = new HashMap(); //自定义的生成器(HttpClientGenerator)注意导入的应为自定义的HttpClientGenerator类,而不是WebMagic依赖中的HttpClientGenerator类。 private HttpClientGenerator httpClientGenerator = new HttpClientGenerator(); private HttpUriRequestConverter httpUriRequestConverter = new HttpUriRequestConverter(); private ProxyProvider proxyProvider; private boolean responseHeader = true; public void setHttpUriRequestConverter(HttpUriRequestConverter httpUriRequestConverter) { this.httpUriRequestConverter = httpUriRequestConverter; } public void setProxyProvider(ProxyProvider proxyProvider) { this.proxyProvider = proxyProvider; } private CloseableHttpClient getHttpClient(Site site) { if (site == null) { return httpClientGenerator.getClient(null); } String domain = site.getDomain(); CloseableHttpClient httpClient = httpClients.get(domain); if (httpClient == null) { synchronized (this) { httpClient = httpClients.get(domain); if (httpClient == null) { httpClient = httpClientGenerator.getClient(site); httpClients.put(domain, httpClient); } } } return httpClient; } @Override public Page download(Request request, Task task) { if (task == null || task.getSite() == null) { throw new NullPointerException("task or site can not be null"); } CloseableHttpResponse httpResponse = null; CloseableHttpClient httpClient = getHttpClient(task.getSite()); Proxy proxy = proxyProvider != null ? proxyProvider.getProxy(task) : null; HttpClientRequestContext requestContext = httpUriRequestConverter.convert(request, task.getSite(), proxy); Page page = Page.fail(); try { httpResponse = httpClient.execute(requestContext.getHttpUriRequest(), requestContext.getHttpClientContext()); page = handleResponse(request, request.getCharset() != null ? request.getCharset() : task.getSite().getCharset(), httpResponse, task); onSuccess(request); logger.info("downloading page success {}", request.getUrl()); return page; } catch (IOException e) { logger.warn("download page {} error", request.getUrl(), e); onError(request); return page; } finally { if (httpResponse != null) { //ensure the connection is released back to pool EntityUtils.consumeQuietly(httpResponse.getEntity()); } if (proxyProvider != null && proxy != null) { proxyProvider.returnProxy(proxy, page, task); } } } @Override public void setThread(int thread) { httpClientGenerator.setPoolSize(thread); } protected Page handleResponse(Request request, String charset, HttpResponse httpResponse, Task task) throws IOException { byte[] bytes = IOUtils.toByteArray(httpResponse.getEntity().getContent()); String contentType = httpResponse.getEntity().getContentType() == null ? "" : httpResponse.getEntity().getContentType().getValue(); Page page = new Page(); page.setBytes(bytes); if (!request.isBinaryContent()){ if (charset == null) { charset = getHtmlCharset(contentType, bytes); } page.setCharset(charset); page.setRawText(new String(bytes, charset)); } page.setUrl(new PlainText(request.getUrl())); page.setRequest(request); page.setStatusCode(httpResponse.getStatusLine().getStatusCode()); page.setDownloadSuccess(true); if (responseHeader) { page.setHeaders(HttpClientUtils.convertHeaders(httpResponse.getAllHeaders())); } return page; } private String getHtmlCharset(String contentType, byte[] contentBytes) throws IOException { String charset = CharsetUtils.detectCharset(contentType, contentBytes); if (charset == null) { charset = Charset.defaultCharset().name(); logger.warn("Charset autodetect failed, use {} as charset. Please specify charset in Site.setCharset()", Charset.defaultCharset()); } return charset; } }

然后在自定义的HttpClientGenerator类中修改有关ssl的参数

(!!!摘自webMagic框架中HttpClientGenerator,基于此类修改!!!)

/*
自定义的HttpClientGenerator生成器
*/

package com.sealion_crawler.project.spider_download;

import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.client.CookieStore;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.config.SocketConfig;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.DefaultHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.*;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.impl.cookie.BasicClientCookie;
import org.apache.http.protocol.HttpContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.downloader.CustomRedirectStrategy;

import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.IOException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Map;

/**
 * @author code4crafter@gmail.com 
* @since 0.4.0 */ public class HttpClientGenerator { private transient Logger logger = LoggerFactory.getLogger(getClass()); private PoolingHttpClientConnectionManager connectionManager; public HttpClientGenerator() { Registry reg = RegistryBuilder.create() .register("http", PlainConnectionSocketFactory.INSTANCE) .register("https", buildSSLConnectionSocketFactory()) .build(); connectionManager = new PoolingHttpClientConnectionManager(reg); connectionManager.setDefaultMaxPerRoute(100); } /* 此方法中设置ssl有关参数。 */ private SSLConnectionSocketFactory buildSSLConnectionSocketFactory() { try { return new SSLConnectionSocketFactory(createIgnoreVerifySSL(), new String[]{"SSLv3", "TLSv1", "TLSv1.1", "TLSv1.2"}, null, new DefaultHostnameVerifier()); // 优先绕过安全证书 } catch (KeyManagementException e) { logger.error("ssl connection fail", e); } catch (NoSuchAlgorithmException e) { logger.error("ssl connection fail", e); } return SSLConnectionSocketFactory.getSocketFactory(); } private SSLContext createIgnoreVerifySSL() throws NoSuchAlgorithmException, KeyManagementException { // 实现一个X509TrustManager接口,用于绕过验证,不用修改里面的方法 X509TrustManager trustManager = new X509TrustManager() { @Override public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException { } @Override public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException { } @Override public X509Certificate[] getAcceptedIssuers() { return null; } }; /* 下面为当前框架默认参数 SSLContext sc = SSLContext.getInstance("SSLv3"); 可修改为需要的ssl参数类型 */ SSLContext sc = SSLContext.getInstance("TLS"); sc.init(null, new TrustManager[] { trustManager }, null); return sc; } public HttpClientGenerator setPoolSize(int poolSize) { connectionManager.setMaxTotal(poolSize); return this; } public CloseableHttpClient getClient(Site site) { return generateClient(site); } private CloseableHttpClient generateClient(Site site) { HttpClientBuilder httpClientBuilder = HttpClients.custom(); httpClientBuilder.setConnectionManager(connectionManager); if (site.getUserAgent() != null) { httpClientBuilder.setUserAgent(site.getUserAgent()); } else { httpClientBuilder.setUserAgent(""); } if (site.isUseGzip()) { httpClientBuilder.addInterceptorFirst(new HttpRequestInterceptor() { public void process( final HttpRequest request, final HttpContext context) throws HttpException, IOException { if (!request.containsHeader("Accept-Encoding")) { request.addHeader("Accept-Encoding", "gzip"); } } }); } //解决post/redirect/post 302跳转问题 httpClientBuilder.setRedirectStrategy(new CustomRedirectStrategy()); SocketConfig.Builder socketConfigBuilder = SocketConfig.custom(); socketConfigBuilder.setSoKeepAlive(true).setTcpNoDelay(true); socketConfigBuilder.setSoTimeout(site.getTimeOut()); SocketConfig socketConfig = socketConfigBuilder.build(); httpClientBuilder.setDefaultSocketConfig(socketConfig); connectionManager.setDefaultSocketConfig(socketConfig); httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(site.getRetryTimes(), true)); generateCookie(httpClientBuilder, site); return httpClientBuilder.build(); } private void generateCookie(HttpClientBuilder httpClientBuilder, Site site) { if (site.isDisableCookieManagement()) { httpClientBuilder.disableCookieManagement(); return; } CookieStore cookieStore = new BasicCookieStore(); for (Map.Entry cookieEntry : site.getCookies().entrySet()) { BasicClientCookie cookie = new BasicClientCookie(cookieEntry.getKey(), cookieEntry.getValue()); cookie.setDomain(site.getDomain()); cookieStore.addCookie(cookie); } for (Map.Entry> domainEntry : site.getAllCookies().entrySet()) { for (Map.Entry cookieEntry : domainEntry.getValue().entrySet()) { BasicClientCookie cookie = new BasicClientCookie(cookieEntry.getKey(), cookieEntry.getValue()); cookie.setDomain(domainEntry.getKey()); cookieStore.addCookie(cookie); } } httpClientBuilder.setDefaultCookieStore(cookieStore); } }

好了,到这里 基于WebMagic框架 实现爬虫、包括jsoup的使用总结就到这里的。

看完上述内容,是不是对springBoot+webMagic怎么实现网站爬虫有进一步的了解,如果还想学习更多内容,欢迎关注创新互联行业资讯频道。


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