java爬知乎问题的所有回答

突然想爬知乎问题的答案， 然后就开始研究知乎页面，刚开始是爬浏览器渲染好的页面， 解析DOM，找到特定的标签，

后来发现，每次只能得到页面加载出来的几条数据，想要更多就要下拉页面，然后浏览器自动加载几条数据，这样的话解析DOM没用啊，

不能获得所有的回答，然后就搜索了下问题，发现可以使用模拟浏览器发送请求给服务器，获取服务器响应，解析返回的数据，

有了方法，接着就是分析网络请求了， 我用的是火狐浏览器， 按F12点击 网络

鼠标定位到当前位置的最底端

然后下拉滚动条，感觉已经加载新内容了就可以停止了， 这个时候请求新内容的url肯定已经出来了， 剩下的就是找出这个url。

一种方法是看url的意思， 这个不太好看的出来，另一种就是直接复制url到浏览器， 看返回结果，最后得到的请求url是

把链接拿到浏览器地址栏，查看的结果是

接下来就是写代码了

import com.google.gson.Gson;
import com.google.gson.internal.LinkedTreeMap;
import java.io.*;
import java.net.*;
import java.util.*;


public class ZhiHu {
    public static void main(String[] args){
        //请求链接
        String url = "https://www.zhihu.com/api/v4/questions/62209505/answers?" +
                "include=data[*].is_normal,admin_closed_comment,reward_info," +
                "is_collapsed,annotation_action,annotation_detail,collapse_reason," +
                "is_sticky,collapsed_by,suggest_edit,comment_count,can_comment,content," +
                "editable_content,voteup_count,reshipment_settings,comment_permission," +
                "created_time,updated_time,review_info,relevant_info,question,excerpt," +
                "relationship.is_authorized,is_author,voting,is_thanked,is_nothelp;data[*].mark_infos[*].url;" +
                "data[*].author.follower_count,badge[?(type=best_answerer)].topics&sort_by=default";
        //调用方法
        StringBuffer stringBuffer = sendGet(url,20,0);
        //输出结果
        System.out.println(delHTMLTag(new String(stringBuffer)));
    }
    public static StringBuffer sendGet(String baseUrl,int limit,int offset) {
        //存放每次获取的返回结果
        String responseResult = "";
        //读取服务器响应的流
        BufferedReader bufferedReader = null;
        //存放所有的回答内容
        StringBuffer stringBuffer = new StringBuffer();
        //每次返回的回答数
        int num = 0;
        try {
            //更改链接的limit设置每次返回的回答条数, 更改offset设置查询的起始位置
            //即上一次的limit+offset是下一次的起始位置,经过试验,每次最多只能返回20条结果
            String urlToConnect = baseUrl + "&limit="+limit+"&offset="+offset;
            URL url = new URL(urlToConnect);
            // 打开和URL之间的连接
            URLConnection connection = url.openConnection();
            // 设置通用的请求属性,这个在上面的请求头中可以找到
            connection.setRequestProperty("Referer","https://www.zhihu.com/question/276275499");
            connection.setRequestProperty("origin","https://www.zhihu.com");
            connection.setRequestProperty("x-udid","换成自己的udid");
            connection.setRequestProperty("Cookie","换成自己的cookie值");
            connection.setRequestProperty("accept", "application/json, text/plain, */*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("Host", "www.zhihu.com");
            connection.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0");
            // 建立实际的连接
            connection.connect();
            // 定义 BufferedReader输入流来读取URL的响应
            bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                responseResult += line;
            }
            //将返回结果转成map
            Gson gson = new Gson();
            Map<String, Object> map = new HashMap<String,Object>();
            map = gson.fromJson(responseResult, map.getClass());
            //获取page信息
            LinkedTreeMap<String,Object> pageList = (LinkedTreeMap<String,Object>)map.get("paging");
            //得到总条数
            double totals = (Double)pageList.get("totals");
            //等于0 说明查询的是最后不足20条的回答
            if(totals-(limit + offset) != 0) {
                //如果每页的页数加上起始位置与总条数的差大于20, 可以递归查找下一个20条内容
                if (totals - (limit + offset) > 20) {
                    //追加返回结果
                     stringBuffer.append(sendGet(baseUrl, 20, limit + offset));
                     stringBuffer.append("
");//换行,调整格式

                } else {
                    //如果不大于20,说明是最后的几条了,这时需要修改limit的值
                    stringBuffer.append(sendGet(baseUrl, (int) (totals - (limit + offset)), limit + offset));
                    stringBuffer.append("
");
                }
            }
            //获得包含回答的数组
            ArrayList<LinkedTreeMap<String,String>> dataList = (ArrayList<LinkedTreeMap<String,String>>)map.get("data");
            //追加每一条回答,用于返回
            for(LinkedTreeMap<String,String> contentLink : dataList){
                stringBuffer.append(contentLink.get("content")+"

");
                num++;//本次查询到多少条回答
            }
            System.out.println("回答数  "+num);
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (bufferedReader != null) {
                    bufferedReader.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        //返回本次查到的所有回答
        return stringBuffer;
    }

    private static final String regEx_script = "<script[^>]*?>[\s\S]*?<\/script>"; // 定义script的正则表达式
    private static final String regEx_style = "<style[^>]*?>[\s\S]*?<\/style>"; // 定义style的正则表达式
    private static final String regEx_html = "<[^>]+>"; // 定义HTML标签的正则表达式
    private static final String regEx_space = "\s*|	|
|
";//定义空格回车换行符
    /**
     * @param htmlStr
     * @return
     *  删除Html标签
     */
    public static String delHTMLTag(String htmlStr) {
        Pattern p_script = Pattern.compile(regEx_script, Pattern.CASE_INSENSITIVE);
        Matcher m_script = p_script.matcher(htmlStr);
        htmlStr = m_script.replaceAll(""); // 过滤script标签

        Pattern p_style = Pattern.compile(regEx_style, Pattern.CASE_INSENSITIVE);
        Matcher m_style = p_style.matcher(htmlStr);
        htmlStr = m_style.replaceAll(""); // 过滤style标签

        Pattern p_html = Pattern.compile(regEx_html, Pattern.CASE_INSENSITIVE);
        Matcher m_html = p_html.matcher(htmlStr);
        htmlStr = m_html.replaceAll(""); // 过滤html标签

        
        return htmlStr.replaceAll(" ",""); // 返回文本字符串
    }

}

 输出结果

回答数量越多，显示的时候需要的时间也就越长，显示的顺序跟页面上的不一样， 从下到上，20个一组显示

为了缩短等待时间， 使用多线程

ZhiHuSpider.java   先获取总共的条数,然后offset每次增加20,循环创建线程

import com.google.gson.Gson;
import com.google.gson.internal.LinkedTreeMap;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Map;

public class ZhiHuSpider {
    public static void main(String[] args){
        String baseUrl= "https://www.zhihu.com/api/v4/questions/62209505/answers?" +
                "include=data[*].is_normal,admin_closed_comment,reward_info," +
                "is_collapsed,annotation_action,annotation_detail,collapse_reason," +
                "is_sticky,collapsed_by,suggest_edit,comment_count,can_comment,content," +
                "editable_content,voteup_count,reshipment_settings,comment_permission," +
                "created_time,updated_time,review_info,relevant_info,question,excerpt," +
                "relationship.is_authorized,is_author,voting,is_thanked,is_nothelp;data[*].mark_infos[*].url;" +
                "data[*].author.follower_count,badge[?(type=best_answerer)].topics&sort_by=default";
        //存放每次获取的返回结果
        String responseResult = "";
        BufferedReader bufferedReader = null;
        //存放多有的的回答内容
        StringBuffer stringBuffer = new StringBuffer();
        //每次返回的回答数
        URLConnection connection = null;
        try {
            String urlToConnect = baseUrl+ "&limit="+20+"&offset="+0;
            URL url = new URL(urlToConnect);
            // 打开和URL之间的连接
            connection = url.openConnection();

        // 设置通用的请求属性
        connection.setRequestProperty("Referer","https://www.zhihu.com/question/276275499");
        connection.setRequestProperty("origin","https://www.zhihu.com");
        connection.setRequestProperty("x-udid","换成自己的udid值");
        connection.setRequestProperty("Cookie","换成自己的cookie值");
        connection.setRequestProperty("accept", "application/json, text/plain, */*");
        connection.setRequestProperty("connection", "Keep-Alive");
        connection.setRequestProperty("Host", "www.zhihu.com");
        connection.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0");
        // 建立实际的连接
        connection.connect();
        // 定义 BufferedReader输入流来读取URL的响应
        bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String line = null;
        while ((line = bufferedReader.readLine()) != null) {
            responseResult += line;
        }
        //将返回结果转成map
        Gson gson = new Gson();
        Map<String, Object> map = new HashMap<String,Object>();
        map = gson.fromJson(responseResult, map.getClass());
        //获取page信息
        LinkedTreeMap<String,Object> pageList = (LinkedTreeMap<String,Object>)map.get("paging");
        //得到总条数
        double totals = (Double)pageList.get("totals");
        for(int offset = 0 ;offset < totals; offset += 20){
            SpiderThread spiderThread = new SpiderThread(baseUrl,20,offset);
            new Thread(spiderThread).start();
        }
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
                try {
                    if(bufferedReader != null) {
                        bufferedReader.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }
    }
}

SpiderThread.java   

import com.google.gson.Gson;
import com.google.gson.internal.LinkedTreeMap;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;


public class SpiderThread implements Runnable{
    private String baseUrl;
    private int limit;
    private int offset;

    SpiderThread(String baseUrl,int limit,int offset){
        this.baseUrl = baseUrl;
        this.limit = limit;
        this.offset = offset;
    }
    public void run() {
        System.out.println(delHTMLTag(new String(sendGet(baseUrl,limit,offset))));
    }
    public  StringBuffer sendGet(String baseUrl,int limit,int offset) {
        //存放每次获取的返回结果
        String responseResult = "";
        BufferedReader bufferedReader = null;
        //存放多有的的回答内容
        StringBuffer stringBuffer = new StringBuffer();
        //每次返回的回答数
        int num = 0;
        try {
            //更改链接的limit设置每次返回的回答条数, 更改offset设置查询的起始位置
            //即上一次的limit+offset是下一次的起始位置,经过试验,每次最多只能返回20条结果
            String urlToConnect = baseUrl + "&limit="+limit+"&offset="+offset;
            URL url = new URL(urlToConnect);
            // 打开和URL之间的连接
            URLConnection connection = url.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("Referer","https://www.zhihu.com/question/276275499");
            connection.setRequestProperty("origin","https://www.zhihu.com");
            connection.setRequestProperty("x-udid","换成自己的udid值");
            connection.setRequestProperty("Cookie","换成自己的cookie值");
            connection.setRequestProperty("accept", "application/json, text/plain, */*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("Host", "www.zhihu.com");
            connection.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0");
            // 建立实际的连接
            connection.connect();
            // 定义 BufferedReader输入流来读取URL的响应
            bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                responseResult += line;
            }
            //将返回结果转成map
            Gson gson = new Gson();
            Map<String, Object> map = new HashMap<String,Object>();
            map = gson.fromJson(responseResult, map.getClass());
            //获得包含回答的数组
            ArrayList<LinkedTreeMap<String,String>> dataList = (ArrayList<LinkedTreeMap<String,String>>)map.get("data");
            //追加每一条回答,用于返回
            // String str = null;
            for(LinkedTreeMap<String,String> contentLink : dataList){
                stringBuffer.append(contentLink.get("content")+"

");
                num++;//本次查询到多少条回答
            }
            System.out.println("回答条数====================================="+num);
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (bufferedReader != null) {
                    bufferedReader.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        //返回本次查到的所有回答
        return stringBuffer;
    }

    private static final String regEx_script = "<script[^>]*?>[\s\S]*?<\/script>"; // 定义script的正则表达式
    private static final String regEx_style = "<style[^>]*?>[\s\S]*?<\/style>"; // 定义style的正则表达式
    private static final String regEx_html = "<[^>]+>"; // 定义HTML标签的正则表达式
    private static final String regEx_space = "\s*|	|
|
";//定义空格回车换行符
    /**
     * @param htmlStr
     * @return
     *  删除Html标签
     */
    public static String delHTMLTag(String htmlStr) {
        Pattern p_script = Pattern.compile(regEx_script, Pattern.CASE_INSENSITIVE);
        Matcher m_script = p_script.matcher(htmlStr);
        htmlStr = m_script.replaceAll(""); // 过滤script标签

        Pattern p_style = Pattern.compile(regEx_style, Pattern.CASE_INSENSITIVE);
        Matcher m_style = p_style.matcher(htmlStr);
        htmlStr = m_style.replaceAll(""); // 过滤style标签

        Pattern p_html = Pattern.compile(regEx_html, Pattern.CASE_INSENSITIVE);
        Matcher m_html = p_html.matcher(htmlStr);
        htmlStr = m_html.replaceAll(""); // 过滤html标签

        return htmlStr.replaceAll(" ",""); // 返回文本字符串
    }

}

 遇到一个问题

试了下， 其他的都是没问题的，totals就是总条数，就这个有问题，

链接是：https://www.zhihu.com/api/v4/questions/62209505/answers?include=data[*].is_normal,admin_closed_comment,reward_info,is_collapsed,annotation_action,annotation_detail,collapse_reason,is_sticky,collapsed_by,suggest_edit,comment_count,can_comment,content,editable_content,voteup_count,reshipment_settings,comment_permission,created_time,updated_time,review_info,relevant_info,question,excerpt,relationship.is_authorized,is_author,voting,is_thanked,is_nothelp;data[*].mark_infos[*].url;data[*].author.follower_count,badge[?(type=best_answerer)].topics&limit=20&offset=2020&sort_by=default

2018.6.1

添加了个去掉html标签的方法, 显示的更好看点