Python爬取前程无忧十万条招聘数据

前言：本文是介绍利用代理IP池以及多线程完成前程无忧网站的是十万条招聘信息的采集工作，已适当控制采集频率，采集数据仅为了学习使用，采集十万条招聘信息大概需要十个小时。

起因是在知乎上看到另一个程序猿写的前程无忧的爬虫代码，对于他的一些反反爬虫处理措施抱有一丝怀疑态度，于是在他的代码的基础上进行改造，优化了线程的分配以及页面访问的频率，并加入了代理IP池的处理，优化了爬虫效率。

原始代码文章链接：https://zhuanlan.zhihu.com/p/146425439

首先，奉上本文依赖的基础的爬虫代码

def getdata(bot,top):
    for i in range(bot,top):
        print("正在爬取第" + str(i) + "页的数据")
        url0 = "https://search.51job.com/list/000000,000000,0000,00,9,99,%25E6%2595%25B0%25E6%258D%25AE,2,"
        url_end = ".html?"
        url = url0 + str(i) + url_end
        headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36'
        }
        html = requests.get(url, headers=headers)
        html.encoding = "gbk"
        etree = etree.HTML(html.text)
        # ①岗位名称
        JobName = etree.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@title')
        # ②公司名称
        CompanyName = etree.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t2"]/a[@target="_blank"]/@title')
        # ③工作地点
        Address = etree.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t3"]/text()')
        # ④工资
        sal = etree.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t4"]')
        salary = [i.text for i in sal]
        # ⑤发布时间
        ShowTime = etree.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t5"]/text()')
        # ⑥获取职位详情url
        DetailUrl = etree.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@href')
        OthersInfo = []
        JobDescribe = []
        CompanyType = []
        CompanySize = []
        Industry = []
        for i in range(len(DetailUrl)):
            htmlInfo = requests.get(DetailUrl[i], headers=headers)
            htmlInfo.encoding = "gbk"
            etreeInfo = etree.HTML(htmlInfo.text)
            # ⑦经验、学历信息等其他信息
            otherinfo = etreeInfo.xpath('//div[@class="tHeader tHjob"]//div[@class="cn"]/p[@class="msg ltype"]/text()')
            # ⑧岗位详情
            JobDescibe = etreeInfo.xpath('//div[@class="tBorderTop_box"]//div[@class="bmsg job_msg inbox"]/p/text()')
            # ⑨公司类型
            CompanyType = etreeInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[1]/@title')
            # ⑩公司规模(人数)
            CompanySize = etreeInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[2]/@title')
            # ⑪所属行业(公司)
            industry = etreeInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[3]/@title')
            #将上述信息存入列表中
            OthersInfo.append(otherinfo)
            JobDescribe.append(JobDescibe)
            CompanyType.append(CompanyType)
            CompanySize.append(CompanySize)
            Industry.append(industry)
            # 休眠
            time.sleep(0.5)
        # 一边爬取一边写入
        data = pd.DataFrame()
        data["岗位名称"] = JobName
        data["工作地点"] = Address
        data["公司名称"] = CompanyName
        data["工资"] = salary
        data["发布日期"] = ShowTime
        data["经验、学历"] = OthersInfo
        data["所属行业"] = Industry
        data["公司类型"] = CompanyType
        data["公司规模"] = CompanySize
        data["岗位描述"] = JobDescribe
        # 有些网页会跳转到公司官网，会返回空值，所以将其忽略
        try:
            data.to_csv("job_info.csv", mode="a+", header=None, index=None, encoding="gbk")
        except:
            print("跳转官网，无数据")
        time.sleep(1)
    print("数据爬取完成!!!!")

经过实验，发现这段代码存在以下几个问题，1.爬虫的效率低；2.爬虫的过程中报错有点频繁；3.访问网页的延时时间都是固定的，这样很容易被网站识别到

首先，解决第一个问题，原作者的解决方案是以多线程的方式处理，代码如下

import requests,time,warnings,threading
import pandas as pd
from lxml import etree
warnings.filterwarnings("ignore")

def getdata(bot,top):
    for i in range(bot,top):
        print("正在爬取第" + str(i) + "页的数据")
        url0 = "https://search.51job.com/list/000000,000000,0000,00,9,99,%25E6%2595%25B0%25E6%258D%25AE,2,"
        url_end = ".html?"
        url = url0 + str(i) + url_end
        headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36'
        }
        html = requests.get(url, headers=headers)
        html.encoding = "gbk"
        Html = etree.HTML(html.text)
        # ①岗位名称
        JobName = Html.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@title')
        # ②公司名称
        CompanyName = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t2"]/a[@target="_blank"]/@title')
        # ③工作地点
        Address = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t3"]/text()')
        # ④工资
        sal = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t4"]')
        salary = [i.text for i in sal]
        # ⑤发布时间
        ShowTime = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t5"]/text()')
        # ⑥获取职位详情url
        DetailUrl = Html.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@href')
        OthersInfo = []
        JobDescribe = []
        CompanyType = []
        CompanySize = []
        Industry = []
        for i in range(len(DetailUrl)):
            HtmlInfo = requests.get(DetailUrl[i], headers=headers)
            HtmlInfo.encoding = "gbk"
            HtmlInfo = etree.HTML(HtmlInfo.text)
            # ⑦经验、学历信息等其他信息
            otherinfo = HtmlInfo.xpath('//div[@class="tHeader tHjob"]//div[@class="cn"]/p[@class="msg ltype"]/text()')
            # ⑧岗位详情
            JobDescibe = HtmlInfo.xpath('//div[@class="tBorderTop_box"]//div[@class="bmsg job_msg inbox"]/p/text()')
            # ⑨公司类型
            ComType = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[1]/@title')
            # ⑩公司规模(人数)
            ComSize = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[2]/@title')
            # ⑪所属行业(公司)
            industry = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[3]/@title')
            #将上述信息存入列表中
            OthersInfo.append(otherinfo)
            JobDescribe.append(JobDescibe)
            CompanyType.append(ComType)
            CompanySize.append(ComSize)
            Industry.append(industry)
            # 休眠
            time.sleep(0.5)
        # 一边爬取一边写入
        data = pd.DataFrame()
        data["岗位名称"] = JobName
        data["工作地点"] = Address
        data["公司名称"] = CompanyName
        data["工资"] = salary
        data["发布日期"] = ShowTime
        data["经验、学历"] = OthersInfo
        data["所属行业"] = Industry
        data["公司类型"] = CompanyType
        data["公司规模"] = CompanySize
        data["岗位描述"] = JobDescribe
        # 有些网页会跳转到公司官网，会返回空值，所以将其忽略
        try:
            data.to_csv("job_info.csv", mode="a+", header=None, index=None, encoding="gbk")
        except:
            print("跳转官网，无数据")
        time.sleep(1)
    print("数据爬取完成!!!!")

threads = []
t1 = threading.Thread(target=getdata,args=(1,125))
threads.append(t1)
t2 = threading.Thread(target=getdata,args=(125,250))
threads.append(t2)
t3 = threading.Thread(target=getdata,args=(250,375))
threads.append(t3)
t4 = threading.Thread(target=getdata,args=(375,500))
threads.append(t4)
t5 = threading.Thread(target=getdata,args=(500,625))
threads.append(t5)
t6 = threading.Thread(target=getdata,args=(625,750))
threads.append(t6)
t7 = threading.Thread(target=getdata,args=(750,875))
threads.append(t7)
t8 = threading.Thread(target=getdata,args=(875,1000))
threads.append(t8)
t9 = threading.Thread(target=getdata,args=(1000,1125))
threads.append(t9)
t10 = threading.Thread(target=getdata,args=(1125,1250))
threads.append(t10)
t11 = threading.Thread(target=getdata,args=(1250,1375))
threads.append(t11)
t12 = threading.Thread(target=getdata,args=(1375,1500))
threads.append(t12)

if __name__ == "__main__":
    for t in threads:
        t.setDaemon(True)
        t.start()

确实增加了爬虫的速度，但这样做会有一个问题，就是爬虫的质量变差了，准确的说就是出错的几率提高了，被反爬虫策略识别到的次数增加了

首先从代码生成的角度，我优化了一下多线程的生成方法，允许用户自定义线程数作为参数传递，通过总的页数进行均分，如下所示

# 分配线程任务
def start_spider(num):
    start = 1
    end = 0
    count = 2000
    size = count//(num-1)
    print(size)
    while num > 1:
        end = start+size
        t = threading.Thread(target=getdata,args=(start,end))
        start = end+1
        t.start()
        num = num-1
    # 分配剩下的任务给新的线程
    if(end < count):
        start = end+1
        end = count
        t = threading.Thread(target=getdata,args=(start,end))
        t.start()

代码优化了之后，我们调整下爬虫时页面访问的延迟，改为一个随机数

            Industry.append(industry)
            # 休眠
            time.sleep(random.uniform(0.1,1))
        # 一边爬取一边写入
        data = pd.DataFrame()
        data["岗位名称"] = JobName
        data["工作地点"] = Address
        data["公司名称"] = CompanyName
        data["工资"] = salary
        data["发布日期"] = ShowTime
        data["经验、学历"] = OthersInfo
        data["所属行业"] = Industry
        data["公司类型"] = CompanyType
        data["公司规模"] = CompanySize
        data["岗位描述"] = JobDescribe
        # 有些网页会跳转到公司官网，会返回空值，所以将其忽略
        try:
            data.to_csv("job_info.csv", mode="a+", header=None, index=None, encoding="gbk")
        except:
            print("跳转官网，无数据")
        time.sleep(random.uniform(0.2,0.5))

最后利用代理IP池的方式来提高爬虫的质量

这里我分享一个很好用的代理IP池项目：https://github.com/jhao104/proxy_pool

这个项目在我等会分享的gitee开源项目中也拷贝了一份:https://gitee.com/chengrongkai/OpenSpiders

配置IP代理池的方法就参考这个项目的readme就行了

下面我奉上我对这个项目的代码改造

# 利用代理IP请求
def getHtml(url):
    # ....
    retry_count = 5
    proxy = get_proxy().get("proxy")
    while retry_count > 0:
        try:
            headers = {
                        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36'
                    }
            print("代理信息:{}".format(proxy))
            html = requests.get(url,headers=headers, proxies={"http": "http://{}".format(proxy)})
            # 使用代理访问
            return html
        except Exception:
            retry_count -= 1
    # 出错5次, 删除代理池中代理
    delete_proxy(proxy)
    return None

def getdata(bot,top):
    for i in range(bot,top):
        print("正在爬取第" + str(i) + "页的数据")
        url0 = "https://search.51job.com/list/000000,000000,0000,00,9,99,%25E6%2595%25B0%25E6%258D%25AE,2,"
        url_end = ".html?"
        url = url0 + str(i) + url_end
        html = getHtml(url)
        if(html == None):
            continue
        html.encoding = "gbk"
        Html = etree.HTML(html.text)
        # ①岗位名称
        JobName = Html.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@title')
        # ②公司名称
        CompanyName = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t2"]/a[@target="_blank"]/@title')
        # ③工作地点
        Address = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t3"]/text()')
        # ④工资
        sal = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t4"]')
        salary = [i.text for i in sal]
        # ⑤发布时间
        ShowTime = Html.xpath('//div[@class="dw_table"]/div[@class="el"]/span[@class="t5"]/text()')
        # ⑥获取职位详情url
        DetailUrl = Html.xpath('//div[@class="dw_table"]/div[@class="el"]//p/span/a[@target="_blank"]/@href')
        OthersInfo = []
        JobDescribe = []
        CompanyType = []
        CompanySize = []
        Industry = []
        for i in range(len(DetailUrl)):
            HtmlInfo = getHtml(DetailUrl[i])
            HtmlInfo.encoding = "gbk"
            HtmlInfo = etree.HTML(HtmlInfo.text)
            if(HtmlInfo == None):
                continue
            # ⑦经验、学历信息等其他信息
            otherinfo = HtmlInfo.xpath('//div[@class="tHeader tHjob"]//div[@class="cn"]/p[@class="msg ltype"]/text()')
            # ⑧岗位详情
            JobDescibe = HtmlInfo.xpath('//div[@class="tBorderTop_box"]//div[@class="bmsg job_msg inbox"]/p/text()')
            # ⑨公司类型
            ComType = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[1]/@title')
            # ⑩公司规模(人数)
            ComSize = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[2]/@title')
            # ⑪所属行业(公司)
            industry = HtmlInfo.xpath('//div[@class="tCompany_sidebar"]//div[@class="com_tag"]/p[3]/@title')
            #将上述信息存入列表中
            OthersInfo.append(otherinfo)
            JobDescribe.append(JobDescibe)
            CompanyType.append(ComType)
            CompanySize.append(ComSize)
            Industry.append(industry)
            # 休眠
            time.sleep(random.uniform(0.1,1))
        # 一边爬取一边写入
        data = pd.DataFrame()
        data["岗位名称"] = JobName
        data["工作地点"] = Address
        data["公司名称"] = CompanyName
        data["工资"] = salary
        data["发布日期"] = ShowTime
        data["经验、学历"] = OthersInfo
        data["所属行业"] = Industry
        data["公司类型"] = CompanyType
        data["公司规模"] = CompanySize
        data["岗位描述"] = JobDescribe
        # 有些网页会跳转到公司官网，会返回空值，所以将其忽略
        try:
            data.to_csv("job_info.csv", mode="a+", header=None, index=None, encoding="gbk")
        except:
            print("跳转官网，无数据")
        time.sleep(random.uniform(0.2,0.5))
        print("数据爬取完成!!!!")

我自己的机器测试了下，8个线程爬取了一个半小时，采集了一万五的数据，这里我有意的降慢了速度，大家可以根据实际情况进行调整，比如代理IP的重试可以去掉，如果出现无法采集就直接删除代理IP池中的该IP即可，另外线程数也可以按照电脑配置适当增加，在不计质量的情况下，应该可以达到一个小时一万五左右的采集量，单机的情况下，如果有更好的解决方案，欢迎留言，下篇文章将讲述如何对获取到的数据进行清洗以及数据分析。

本文所有代码均开源在https://gitee.com/chengrongkai/OpenSpiders

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