Jsoup初探

简介

jsoup is an open-source Java library of methods designed to extract and manipulate data stored in HTML documents.

Jsoup就是一个用java语言编写用来获取和操控html页面及元素的开源Jar包。
我们使用的一般是1.7的版本，博主用的是jsoup-1.7.2.jar

文档

jsoup有官方的中文使用文档，比较简单jsoup Cookbook(中文版)

用法

一小段代码爬取我的博客文章标题列表，带您简单了解它的用法
选择器截图：

主页选择器

package com.blog.jsoup;

import java.io.IOException;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;

public class BlogSpider {

public static void main(String[] args) {
  try {
    Document doc = Jsoup.connect("http://www.jianshu.com/users/7a8e041a132c/latest_articles").get();
    //通过选择器获取文章列表，选择器dom元素直接通过Chrome开发者工具检查元素Copy -> Copy Selector即可获取
    Elements articleList = doc.select("#list-container > ul > li > div > h4 > a");
    for (int i = 0; i < articleList.size(); i++) {
      System.out.println(articleList.get(i).text());
    }
  } catch (IOException e) {
    e.printStackTrace();
  }

}

}

运行结果如下：

运行结果

细心的读者可能会发现进入我的博客主页之后最新文章列表不止爬取显示的九篇，而是会不断加载更多，这是因为访问这个页面时生成的静态页面只请求了第一页的数据，而随着用户下拉，异步加载了更多的数据，这个是在浏览器生成静态页面之后做的，所以在这里没有办法拿到。这说明了很重要的一点，Jsoup访问页面所拿到的html是我们传统意义上查看网页源代码的数据，而不是你在审查元素的那些数据，所以，想要拿到异步加载的数据需要去解析异步访问的js，然后通过抓包来查看访问的servlet看看能不能模拟访问拿到更多数据。

访问https页面

由于https的证书加密了，直接通过上述方法去访问并提取html页面也会报错

javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No subject alternative DNS name matching m.v.qq.com found.
at com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Alerts.java:174)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1747)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:241)
at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Handshaker.java:235)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1209)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:135)
at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:593)
at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:529)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:943)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1188)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1215)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1199)
at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:476)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:166)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:133)
at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:439)
at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:424)
at org.jsoup.helper.HttpConnection.execute(HttpConnection.java:178)
at org.jsoup.helper.HttpConnection.get(HttpConnection.java:167)
at com.blog.jsoup.BlogSpider.main(BlogSpider.java:13)
Caused by: java.security.cert.CertificateException: No subject alternative DNS name matching m.v.qq.com found.
at sun.security.util.HostnameChecker.matchDNS(HostnameChecker.java:193)
at sun.security.util.HostnameChecker.match(HostnameChecker.java:77)
at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:264)
at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:250)
at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1188)
... 15 more

好在java有提供相应的方法去访问：
为了阅读方便，贴出整个class

package com.blog.jsoup;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.security.SecureRandom;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import javax.security.cert.CertificateException;
import javax.security.cert.X509Certificate;

import org.apache.http.conn.ssl.AllowAllHostnameVerifier;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;

public class BlogSpider {

public static void main(String[] args) {
try {
  Document doc = Jsoup.connect("http://www.jianshu.com/users/7a8e041a132c/latest_articles").get();
  // 通过选择器获取文章列表，选择器dom元素直接通过Chrome开发者工具检查元素Copy -> Copy Selector即可获取
  Elements articleList = doc.select("#list-container > ul > li > div > h4 > a");
  for (int i = 0; i < articleList.size(); i++) {
    System.out.println(articleList.get(i).text());
  }
} catch (IOException e) {
  e.printStackTrace();
}
try {
  SSLSocketFactory.getSocketFactory().setHostnameVerifier(new AllowAllHostnameVerifier());

  String https = "https://m.v.qq.com/x/page/xxxxxxxxx.html";
  // Document doc = Jsoup.connect(https).get();
  init();
  HttpsURLConnection conn = (HttpsURLConnection) new URL(https).openConnection();
  conn.setDoOutput(true);
  conn.setDoInput(true);
  conn.connect();
  BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
  StringBuffer sb = new StringBuffer();
  String line;
  while ((line = br.readLine()) != null)
    sb.append(line);

  Document doc = Jsoup.parse(sb.toString());
} catch (Exception e) {
  e.printStackTrace();
}

}

public static void init() {
try {
  SSLContext sc = SSLContext.getInstance("TLS");
  sc.init(null, new TrustManager[] { new X509TrustManager() {
    public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
    }

    public void checkServerTrusted(X509Certificate[] chain, String authType)

        throws CertificateException {
    }

    @Override
    public java.security.cert.X509Certificate[] getAcceptedIssuers() {
      return null;
    }

    @Override
    public void checkClientTrusted(java.security.cert.X509Certificate[] arg0, String arg1)
        throws java.security.cert.CertificateException {
      // TODO Auto-generated method stub

    }

    @Override
    public void checkServerTrusted(java.security.cert.X509Certificate[] arg0, String arg1)
        throws java.security.cert.CertificateException {
      // TODO Auto-generated method stub

    }
  } }, new SecureRandom());
  HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
  HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier() {
    @Override
    public boolean verify(String arg0, SSLSession arg1) {
      return true;
    }

  });
} catch (Exception e) {
  e.printStackTrace();
}
}

}