Introduction to python crawling web pages

I have written a lot of code about crawlers crawling web pages on the Internet before. Recently, I still want to record the crawlers I wrote so that everyone can use them. Bar!

The code is divided into 4 parts:

Part 1: Find a website.

我这里还是找了一个比较简单的网站，就是大家都知道的https://movie.douban.com/top250?start=
大家可以登录里面看一下。

Here you may have some libraries that have not been installed. The above picture will let you install the libraries needed to crawl web pages. Among them, the libraries I used this time are: bs4, urllib, xlwt, re.

(Free learning recommendation: python video tutorial)

As shown

Select file here -setting-Project-then select the plus sign in the lower left corner and install the files you need by yourself.

The following code is the source code for crawling web pages:

import urllib.requestfrom bs4 import BeautifulSoupimport xlwtimport redef main():
    #   爬取网页
    baseurl = 'https://movie.douban.com/top250?start='
    datalist = getData(baseurl)
    savepath = '豆瓣电影Top250.xls'
    #   保存数据
    saveData(datalist,savepath)
    # askURL("https://movie.douban.com/top250?start=1")#影片详情的规则findLink = re.compile(r'<a>')  #创建从正则表达式，表示规则findImgSrc = re.compile(r'<img . alt="Introduction to python crawling web pages" >(.*)')#影片的评分findReating = re.compile(r'<span>(.*)</span>')#找到评价人数findJudge = re.compile(r'<span>(\d*)人评价</span>')#找到概况findInq = re.compile(r'<span>(.*)</span>')#找到影片的相关内容findBb = re.compile(r'<p>(.*?)</p>', re.S)#re.S忽视换行符</img.></a>

Part 2: Crawl web pages.

def getData(baseurl):
    datalist = []
    for i in range(0, 10):
        url = baseurl + str(i*25)
        html = askURL(url)    #保存获取到的网页源码

        #对网页进行解析
        soup = BeautifulSoup(html, 'html.parser')
        for item in soup.find_all('p', class_="item"):  #查找符合要求的字符串 形成列表
            #print(item)  #测试查看电影信息
            data = []
            item = str(item)
            link = re.findall(findLink, item)[0]  #re库用来查找指定的字符串
            data.append(link)
            imgSrc = re.findall(findImgSrc, item)[0]
            data.append(imgSrc) #添加图片
            titles = re.findall(finTitle, item)         #
            if (len(titles) == 2):
                ctitle = titles[0]      #添加中文名
                data.append(ctitle)
                otitle = titles[1].replace("/", "")   #replace("/", "")去掉无关的符号
                data.append(otitle)     #添加英文名
            else:
                data.append(titles[0])
                data.append(' ')#外国名字留空
            rating = re.findall(findReating, item)[0] #添加评分
            data.append(rating)

            judgeNum = re.findall(findJudge,item) #评价人数
            data.append(judgeNum)
            inq = re.findall(findInq, item)  #添加概述
            if len(inq) != 0:
                inq = inq[0].replace(".", "")  #去掉句号
                data.append(inq)
            else:
                data.append(" ")    #留空
            bd = re.findall(findBb,item)[0]
            bd = re.sub('<br>(\s+)?',' ', bd)  #去掉br  后面这个bd表示对bd进行操作
            bd = re.sub('/', ' ', bd)   #替换/
            data.append(bd.strip())  #去掉前后的空格strip()
            datalist.append(data)   #把处理好的一部电影放入datalist当中

    return datalist

Part 3: Get a specified url information.

#得到指定的一个url网页信息def askURL(url):
    head = {
        "User-Agent": "Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Mobile Safari/537.36"}
    request = urllib.request.Request(url,headers=head)    #  get请求不需要其他的的，而post请求需要 一个method方法
    html = ""
    try:
        response = urllib.request.urlopen(request)
        html = response.read().decode('utf-8')
        # print(html)
    except Exception as e:
        if hasattr(e,'code'):
            print(e.code)
        if hasattr(e,'reason'):
            print(e.reason)
    return  html

Part 4: Saving Data

#    3:保存数据def saveData(datalist,savepath):

    book = xlwt.Workbook(encoding="utf-8", style_compression=0)
    sheet = book.add_sheet('豆瓣电影Top250', cell_overwrite_ok=True)
    col = ('电影详情链接', '图片链接', '影片中文名', '影片外国名', '评分', '评价数', '概况', '相关信息')
    for i in range(0,8):
        sheet.write(0,i,col[i])  #列名
    for i in range(0,250):
        print("第%d条"%i)
        data = datalist[i]
        for j in range(0,8):
            sheet.write(i+1,j,data[j])
    book.save(savepath) #保存

Here, let’s take a look at the code. I wrote it very clearly about the annotation of the code.

Regarding learning this crawler, you also need to learn some basic regular expressions. Of course, basic python syntax is indispensable. I hope it will be helpful to everyone.

Related free learning recommendations: python tutorial(Video)

The above is the detailed content of Introduction to python crawling web pages. For more information, please follow other related articles on the PHP Chinese website!