springBoot+webMagic实现网站爬虫的实例代码

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

<!--WebMagic核心包-->
  <dependency>
   <groupId>us.codecraft</groupId>
   <artifactId>webmagic-core</artifactId>
   <version>0.7.3</version>
   <!--这里可以去掉WebMagic自带的日志（因为打印的很多。。。。）-->
<!--   <exclusions>-->
<!--    <exclusion>-->
<!--     <groupId>org.slf4j</groupId>-->
<!--     <artifactId>slf4j-log4j12</artifactId>-->
<!--    </exclusion>-->
<!--   </exclusions>-->
  </dependency>
  <!--WebMagic扩展-->
  <dependency>
   <groupId>us.codecraft</groupId>
   <artifactId>webmagic-extension</artifactId>
   <version>0.7.3</version>
  </dependency>

  <!--WebMagic对布隆过滤器的支持-->
  <dependency>
   <groupId>com.google.guava</groupId>
   <artifactId>guava</artifactId>
   <version>16.0</version>
  </dependency>

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<Selectable> 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 <br>
 * @since 0.1.0
 */
public class HttpClientDownloader extends AbstractDownloader {

 private Logger logger = LoggerFactory.getLogger(getClass());

 private final Map<String, CloseableHttpClient> httpClients = new HashMap<String, CloseableHttpClient>();

 //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 <br>
 * @since 0.4.0
 */
public class HttpClientGenerator {

 private transient Logger logger = LoggerFactory.getLogger(getClass());

 private PoolingHttpClientConnectionManager connectionManager;

 public HttpClientGenerator() {
  Registry<ConnectionSocketFactory> reg = RegistryBuilder.<ConnectionSocketFactory>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<String, String> cookieEntry : site.getCookies().entrySet()) {
   BasicClientCookie cookie = new BasicClientCookie(cookieEntry.getKey(), cookieEntry.getValue());
   cookie.setDomain(site.getDomain());
   cookieStore.addCookie(cookie);
  }
  for (Map.Entry<String, Map<String, String>> domainEntry : site.getAllCookies().entrySet()) {
   for (Map.Entry<String, String> 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。

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