最近在学习nodejs爬虫技术，学了request模块，所以想着写一个自己的爬虫项目，研究了半天，最后选定indeed作为目标网站，通过爬取indeed的职位数据，然后开发一个自己的职位搜索引擎，目前已经上线了，虽然功能还是比较简单，但还是贴一下网址job search engine，证明一下这个爬虫项目是有用的。下面就来讲讲整个爬虫的思路。
确定入口页面
众所周知，爬虫是需要入口页面的，通过入口页面，不断的爬取链接，最后爬取完整个网站。在这个第一步的时候，就遇到了困难，一般来说都是选取首页和列表页作为入口页面的，但是indeed的列表页面做了限制，不能爬取完整的列表，顶多只能抓取前100页，但是这没有难倒我，我发现indeed有一个Browse Jobs 页面，通过这个页面，可以获取indeed按地区搜索和按类型搜索的所有列表。下面贴一下这个页面的解析代码。
start: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
try {
const $ = cheerio.load(iconv.decode(page.con, 'utf-8'), { decodeEntities: false });
$('#states > tbody > tr > td > a').each((i, ele) => {
const url = URL.resolve(page.url, $(ele).attr('href'));
tasks.push({ _id: md5(url), type: 'city', host, url, done: 0, name: $(ele).text() });
});
$('#categories > tbody > tr > td > a').each((i, ele) => {
const url = URL.resolve(page.url, $(ele).attr('href'));
tasks.push({ _id: md5(url), type: 'category', host, url, done: 0, name: $(ele).text() });
});
const res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-start insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-start parse ${page.url} ${err}`);
return 0;
}
}
通过cheerio解析html内容，把按地区搜索和按类型搜索链接插入到数据库中。
爬虫架构
这里简单讲一下我的爬虫架构思路，数据库选用mongodb。每一个待爬取的页面存一条记录page，包含id,url,done,type,host等字段，id用md5(url)生成，避免重复。每一个type有一个对应的html内容解析方法，主要的业务逻辑都集中在这些解析方法里面，上面贴出来的代码就是例子。
爬取html采用request模块，进行了简单的封装，把callback封装成promise，方便使用async和await方式调用，代码如下。
const req = require('request');
const request = req.defaults({
headers: {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36'
},
timeout: 30000,
encoding: null
});
const fetch = (url) => new Promise((resolve) => {
console.log(`down ${url} started`);
request(encodeURI(url), (err, res, body) => {
if (res && res.statusCode === 200) {
console.log(`down ${url} 200`);
resolve(body);
} else {
console.error(`down ${url} ${res && res.statusCode} ${err}`);
if (res && res.statusCode) {
resolve(res.statusCode);
} else {
// ESOCKETTIMEOUT 超时错误返回600
resolve(600);
}
}
});
});
做了简单的反反爬处理，把user-agent改成电脑通用的user-agent，设置了超时时间30秒，其中encoding: null设置request直接返回buffer，而不是解析后的内容，这样的好处是如果页面是gbk或者utf-8编码，只要解析html的时候指定编码就行了，如果这里指定encoding: utf-8，则当页面编码是gbk的时候，页面内容会乱码。
request默认是回调函数形式，通过promise封装，如果成功，则返回页面内容的buffer，如果失败，则返回错误状态码，如果超时，则返回600，这些懂nodejs的应该很好理解。
完整的解析代码
const URL = require('url');
const md5 = require('md5');
const cheerio = require('cheerio');
const iconv = require('iconv-lite');
const json = (data) => {
let res;
try {
res = JSON.parse(data);
} catch (err) {
console.error(err);
}
return res;
};
const rules = [
/\/jobs\?q=.*&sort=date&start=\d+/,
/\/jobs\?q=&l=.*&sort=date&start=\d+/
];
const fns = {
start: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
try {
const $ = cheerio.load(iconv.decode(page.con, 'utf-8'), { decodeEntities: false });
$('#states > tbody > tr > td > a').each((i, ele) => {
const url = URL.resolve(page.url, $(ele).attr('href'));
tasks.push({ _id: md5(url), type: 'city', host, url, done: 0, name: $(ele).text() });
});
$('#categories > tbody > tr > td > a').each((i, ele) => {
const url = URL.resolve(page.url, $(ele).attr('href'));
tasks.push({ _id: md5(url), type: 'category', host, url, done: 0, name: $(ele).text() });
});
const res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-start insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-start parse ${page.url} ${err}`);
return 0;
}
},
city: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
const cities = [];
try {
const $ = cheerio.load(iconv.decode(page.con, 'utf-8'), { decodeEntities: false });
$('#cities > tbody > tr > td > p.city > a').each((i, ele) => {
// https://www.indeed.com/l-Charlotte,-NC-jobs.html
let tmp = $(ele).attr('href').match(/l-(?<loc>.*)-jobs.html/u);
if (!tmp) {
tmp = $(ele).attr('href').match(/l=(?<loc>.*)/u);
}
const { loc } = tmp.groups;
const url = `https://www.indeed.com/jobs?l=${decodeURIComponent(loc)}&sort=date`;
tasks.push({ _id: md5(url), type: 'search', host, url, done: 0 });
cities.push({ _id: `${$(ele).text()}_${page.name}`, parent: page.name, name: $(ele).text(), url });
});
let res = await global.com.city.insertMany(cities, { ordered: false }).catch(() => {});
res && console.log(`${host}-city insert ${res.insertedCount} from ${cities.length} cities`);
res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-city insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-city parse ${page.url} ${err}`);
return 0;
}
},
category: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
const categories = [];
try {
const $ = cheerio.load(iconv.decode(page.con, 'utf-8'), { decodeEntities: false });
$('#titles > tbody > tr > td > p.job > a').each((i, ele) => {
const { query } = $(ele).attr('href').match(/q-(?<query>.*)-jobs.html/u).groups;
const url = `https://www.indeed.com/jobs?q=${decodeURIComponent(query)}&sort=date`;
tasks.push({ _id: md5(url), type: 'search', host, url, done: 0 });
categories.push({ _id: `${$(ele).text()}_${page.name}`, parent: page.name, name: $(ele).text(), url });
});
let res = await global.com.category.insertMany(categories, { ordered: false }).catch(() => {});
res && console.log(`${host}-category insert ${res.insertedCount} from ${categories.length} categories`);
res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-category insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-category parse ${page.url} ${err}`);
return 0;
}
},
search: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
const durls = [];
try {
const con = iconv.decode(page.con, 'utf-8');
const $ = cheerio.load(con, { decodeEntities: false });
const list = con.match(/jobmap\[\d+\]= {.*}/g);
const jobmap = [];
if (list) {
// eslint-disable-next-line no-eval
list.map((item) => eval(item));
}
for (const item of jobmap) {
const cmplink = URL.resolve(page.url, item.cmplnk);
const { query } = URL.parse(cmplink, true);
let name;
if (query.q) {
// eslint-disable-next-line prefer-destructuring
name = query.q.split(' #')[0].split('#')[0];
} else {
const tmp = cmplink.match(/q-(?<text>.*)-jobs.html/u);
if (!tmp) {
// eslint-disable-next-line no-continue
continue;
}
const { text } = tmp.groups;
// eslint-disable-next-line prefer-destructuring
name = text.replace(/-/g, ' ').split(' #')[0];
}
const surl = `https://www.indeed.com/cmp/_cs/cmpauto?q=${name}&n=10&returnlogourls=1&returncmppageurls=1&caret=8`;
const burl = `https://www.indeed.com/viewjob?jk=${item.jk}&from=vjs&vjs=1`;
const durl = `https://www.indeed.com/rpc/jobdescs?jks=${item.jk}`;
tasks.push({ _id: md5(surl), type: 'suggest', host, url: surl, done: 0 });
tasks.push({ _id: md5(burl), type: 'brief', host, url: burl, done: 0 });
durls.push({ _id: md5(durl), type: 'detail', host, url: durl, done: 0 });
}
$('a[href]').each((i, ele) => {
const tmp = URL.resolve(page.url, $(ele).attr('href'));
const [url] = tmp.split('#');
const { path, hostname } = URL.parse(url);
for (const rule of rules) {
if (rule.test(path)) {
if (hostname == host) {
// tasks.push({ _id: md5(url), type: 'list', host, url: decodeURI(url), done: 0 });
}
break;
}
}
});
let res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-search insert ${res.insertedCount} from ${tasks.length} tasks`);
res = await global.com.task.insertMany(durls, { ordered: false }).catch(() => {});
res && console.log(`${host}-search insert ${res.insertedCount} from ${durls.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-search parse ${page.url} ${err}`);
return 0;
}
},
suggest: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
const companies = [];
try {
const con = page.con.toString('utf-8');
const data = json(con);
for (const item of data) {
const id = item.overviewUrl.replace('/cmp/', '');
const cmpurl = `https://www.indeed.com/cmp/${id}`;
const joburl = `https://www.indeed.com/cmp/${id}/jobs?clearPrefilter=1`;
tasks.push({ _id: md5(cmpurl), type: 'company', host, url: cmpurl, done: 0 });
tasks.push({ _id: md5(joburl), type: 'jobs', host, url: joburl, done: 0 });
companies.push({ _id: id, name: item.name, url: cmpurl });
}
let res = await global.com.company.insertMany(companies, { ordered: false }).catch(() => {});
res && console.log(`${host}-suggest insert ${res.insertedCount} from ${companies.length} companies`);
res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-suggest insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-suggest parse ${page.url} ${err}`);
return 0;
}
},
// list: () => {},
jobs: async (page) => {
const host = URL.parse(page.url).hostname;
const tasks = [];
const durls = [];
try {
const con = iconv.decode(page.con, 'utf-8');
const tmp = con.match(/window._initialData=(?<text>.*);<\/script><script>window._sentryData/u);
let data;
if (tmp) {
const { text } = tmp.groups;
data = json(text);
if (data.jobList && data.jobList.pagination && data.jobList.pagination.paginationLinks) {
for (const item of data.jobList.pagination.paginationLinks) {
// eslint-disable-next-line max-depth
if (item.href) {
item.href = item.href.replace(/\u002F/g, '/');
const url = URL.resolve(page.url, decodeURI(item.href));
tasks.push({ _id: md5(url), type: 'jobs', host, url: decodeURI(url), done: 0 });
}
}
}
if (data.jobList && data.jobList.jobs) {
for (const job of data.jobList.jobs) {
const burl = `https://www.indeed.com/viewjob?jk=${job.jobKey}&from=vjs&vjs=1`;
const durl = `https://www.indeed.com/rpc/jobdescs?jks=${job.jobKey}`;
tasks.push({ _id: md5(burl), type: 'brief', host, url: burl, done: 0 });
durls.push({ _id: md5(durl), type: 'detail', host, url: durl, done: 0 });
}
}
} else {
console.log(`${host}-jobs ${page.url} has no _initialData`);
}
let res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-search insert ${res.insertedCount} from ${tasks.length} tasks`);
res = await global.com.task.insertMany(durls, { ordered: false }).catch(() => {});
res && console.log(`${host}-search insert ${res.insertedCount} from ${durls.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-jobs parse ${page.url} ${err}`);
return 0;
}
},
brief: async (page) => {
const host = URL.parse(page.url).hostname;
try {
const con = page.con.toString('utf-8');
const data = json(con);
data.done = 0;
data.views = 0;
data.host = host;
// format publish date
if (data.vfvm && data.vfvm.jobAgeRelative) {
const str = data.vfvm.jobAgeRelative;
const tmp = str.split(' ');
const [first, second] = tmp;
if (first == 'Just' || first == 'Today') {
data.publishDate = Date.now();
} else {
const num = first.replace(/\+/, '');
if (second == 'hours') {
const date = new Date();
const time = date.getTime();
// eslint-disable-next-line no-mixed-operators
date.setTime(time - num * 60 * 60 * 1000);
data.publishDate = date.getTime();
} else if (second == 'days') {
const date = new Date();
const time = date.getTime();
// eslint-disable-next-line no-mixed-operators
date.setTime(time - num * 24 * 60 * 60 * 1000);
data.publishDate = date.getTime();
} else {
data.publishDate = Date.now();
}
}
}
await global.com.job.updateOne({ _id: data.jobKey }, { $set: data }, { upsert: true }).catch(() => { });
const tasks = [];
const url = `https://www.indeed.com/jobs?l=${data.jobLocationModel.jobLocation}&sort=date`;
tasks.push({ _id: md5(url), type: 'search', host, url, done: 0 });
const res = await global.com.task.insertMany(tasks, { ordered: false }).catch(() => {});
res && console.log(`${host}-brief insert ${res.insertedCount} from ${tasks.length} tasks`);
return 1;
} catch (err) {
console.error(`${host}-brief parse ${page.url} ${err}`);
return 0;
}
},
detail: async (page) => {
const host = URL.parse(page.url).hostname;
try {
const con = page.con.toString('utf-8');
const data = json(con);
const [jobKey] = Object.keys(data);
await global.com.job.updateOne({ _id: jobKey }, { $set: { content: data[jobKey], done: 1 } }).catch(() => { });
return 1;
} catch (err) {
console.error(`${host}-detail parse ${page.url} ${err}`);
return 0;
}
},
run: (page) => {
if (page.type == 'list') {
page.type = 'search';
}
const fn = fns[page.type];
if (fn) {
return fn(page);
}
console.error(`${page.url} parser not found`);
return 0;
}
};
module.exports = fns;
每一个解析方法都会插入一些新的链接，新的链接记录都会有一个type字段，通过type字段，可以知道新的链接的解析方法，这样就能完整解析所有的页面了。例如start方法会插入type为city和category的记录，type为city的页面记录的解析方法就是city方法，city方法里面又会插入type为search的链接，这样一直循环，直到最后的brief和detail方法分别获取职位数据的简介和详细内容。
其实爬虫最关键的就是这些html解析方法，有了这些方法，你就能获取任何想要的结构化内容了。
数据索引
这部分就很简单了，有了前面获取的结构化数据，按照elasticsearch，新建一个schema，然后写个程序定时把职位数据添加到es的索引里面就行了。因为职位详情的内容有点多，我就没有把content字段添加到索引里面了，因为太占内存了，服务器内存不够用了，>_<。
DEMO
最后还是贴上网址供大家检阅，job search engine。
