爬虫实例

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实例1：中国大学排名定向爬虫

功能描述

输入：大学排名URL链接

输出：大学排名信息的屏幕输出（排名，大学名称，总分）

技术路线：requests-bs4

定向爬虫：仅对输入URL进行爬取，不扩展爬取

程序的结构设计

步骤1：从网络上获取大学排名网页内容getHTMLText()

步骤2：提取网页内容中信息到合适的数据结构fillUnivList()

步骤3：利用数据结构展示并输出结果printUnivList()

大学排名除了排名之外还包括大学的基本信息，是一个典型的二维数据结构,所以采用二维列表组织相关信息

import requests
from bs4 import BeautifulSoup
import bs4

def getHTMLText(url):
try:
r = requests.get(url,timeout = 30)
r.raise_for_status()
r.encoding = r.apparent_encoding
return r.text
except:
return ""

def fillUnivList(ulist,html):
soup = BeautifulSoup(html,"html.parser")
for tr in soup.find('tbody').children:
if isinstance(tr,bs4.element.Tag):#检查tr标签的类型，如果tr标签的类型不是bs4库定义的tag类型，将过滤掉
tds = tr('td')
ulist.append((tds[0].string,tds[1].string,tds[3].string))

def printUnivList(ulist,num):
# print("{:^10}\t{:^6}\t{:^10}".format("排名","学校名称","总分"))
# for i in range(num):
# u=ulist[i]
# print("{:^10}\t{:^6}\t{:^10}".format(u[0],u[1],u[2]))
# print("Suc" + str(num))

#对中英文混排输出进行优化
tplt = "{0:^10}\t{1:{3}^10}\t{2:^10}"#{3}指的是在打印学校排名的这一栏中需要填充时，使用format函数的第三个变量进行填充，也就是使用中文的空格来进行填充
print(tplt.format("排名","学校名称","总分",chr(12288)))
for i in range(num):
u=ulist[i]
print(tplt.format(u[0],u[1],u[2],chr(12288)))
print("Suc" + str(num))
def main():
uinfo = []
url = "http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html"
html = getHTMLText(url)
fillUnivList(uinfo,html)
printUnivList(uinfo,20)#20 univs
main()

实例2：淘宝商品信息定向爬虫
功能描述
目标：获取淘宝搜索页面的信息，提取其中的商品名称和价格
理解：淘宝的搜索接口
　　　翻页的处理
技术路线：requests-re
定向爬虫可行性
程序的结构设计
步骤1：提交商品搜索请求，循环获取页面
步骤2：对于每个页面，提取商品名称和价格信息
步骤3：将信息输出到屏幕上

import requests
import re
def getHTMLTest(url):
    try:#coo的值为自己登录淘宝后，输入书包搜索后的cookie
        coo = 'thw=cn; cna=24t1FdsskikCAXEteKSVn8yS; v=0; t=6615fa5b788406278f02379f51d55807; \
        cookie2=55a650e680a8e140771936b04cb56e95; _tb_token_=f68134b3ee336; unb=763489836; \
        uc3=nk2=oAY%2Bx%2FHWV8vidQ%3D%3D&id2=VAcN5rR6zAjv&vt3=F8dBy32junLF5eJpjDs%3D&lg2=VT5L2FSpMGV7TQ%3D%3D;\
        csg=8ec2be45; lgc=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; cookie17=VAcN5rR6zAjv;\
        dnk=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; skt=e8b0543f48622a97; existShop=MTU2NDkwODMzOQ%3D%3D;\
        uc4=id4=0%40Vh5PI3jEh3Oc2p0oDeG%2Fvw4ylAo%3D&nk4=0%40olT0l5EQsQIZXSm9RQUe%2FzVpfGL%2F;\
        tracknick=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; _cc_=VT5L2FSpdA%3D%3D; tg=0; _l_g_=Ug%3D%3D;\
        sg=%E5%A4%9C6f; _nk_=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C;\
        cookie1=Vv6fkO6X3Dbd0%2BjR5Pm9%2FVMegu88LAEuGgMSjoFaFFg%3D;\
        enc=aBauooIlET%2FTz%2FO%2By206HZzzoZUzq%2BmM220DoSa8xXJAwE9%2FtIJe5hfuwu12e9GfpcG%2F9ZNzpm6JBo%2F2D%2BNsig%3D%3D; \
        mt=ci=110_1; hng=CN%7Czh-CN%7CCNY%7C156; swfstore=308335;\
        x=e%3D1%26p%3D*%26s%3D0%26c%3D0%26f%3D0%26g%3D0%26t%3D0%26__ll%3D-1%26_ato%3D0;\
        uc1=cookie14=UoTaHPGk7cSIQw%3D%3D&cookie15=V32FPkk%2Fw0dUvg%3D%3D;\
        whl=-1%260%260%261564908848429; JSESSIONID=9A789A993ECB09BAABEF6E4A29CC2510; \
        l=cBgxe_J4qUKhmO7bBOCg5uI8LO7OSIRA_uPRwCVXi_5Ba6Ls0d_Ok7JG-Fp6VjWd90TB4dG4psy9-etkiKy06Pt-g3fP.;\
        isg=BFtbb-bCgqTERv7QpzRjXQhf6r8FmG5bzZ8Il02YN9pxLHsO1QD_gnmuxswHC8cq'
        r = requests.get(url,headers={'cookie':coo},timeout = 30)
        r.raise_for_status()
        r.encoding = r.apparent_encoding
        return r.text
    except:
        return ""

def parsePage(ilt,html):
    try:
        plt = re.findall(r'\"view_price\"\:\"[\d\.]*\"',html)
        tlt = re.findall(r'\"raw_title\":\".*?\"',html)
        for i in range(len(plt)):
            price = eval(plt[i].split(':')[1])#eval函数可以将获得的字符串的最外层的单引号或者双引号去掉
            title = eval(tlt[i].split(':')[1])
            ilt.append([price,title])
    except:
        print("")

def printGoodsList(ilt):
    tplt = "{:4}\t{:8}\t{:16}"
    print(tplt.format("序号","价格","商品名称"))
    count = 0
    for g in ilt:
        count = count + 1
        print(tplt.format(count,g[0],g[1]))

def main():
    goods = '书包'
    depth = 2
    start_url = 'https://s.taobao.com/search?q=' + goods
    infoList = []
    for i in range(depth):
        try:
            url = start_url + '&s=' + str(44*i)
            html = getHTMLTest(url)
            parsePage(infoList,html)
        except:
            continue
    printGoodsList(infoList)

main()

import requests
import re
def getHTMLTest(url):
    headers = {'user-agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.87 Safari/537.36'}
    try:#coo的值为自己登录淘宝后，输入书包搜索后的cookie
        coo = 'thw=cn; cna=24t1FdsskikCAXEteKSVn8yS; v=0; t=6615fa5b788406278f02379f51d55807; \
        cookie2=55a650e680a8e140771936b04cb56e95; _tb_token_=f68134b3ee336; unb=763489836; \
        uc3=nk2=oAY%2Bx%2FHWV8vidQ%3D%3D&id2=VAcN5rR6zAjv&vt3=F8dBy32junLF5eJpjDs%3D&lg2=VT5L2FSpMGV7TQ%3D%3D;\
        csg=8ec2be45; lgc=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; cookie17=VAcN5rR6zAjv;\
        dnk=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; skt=e8b0543f48622a97; existShop=MTU2NDkwODMzOQ%3D%3D;\
        uc4=id4=0%40Vh5PI3jEh3Oc2p0oDeG%2Fvw4ylAo%3D&nk4=0%40olT0l5EQsQIZXSm9RQUe%2FzVpfGL%2F;\
        tracknick=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C; _cc_=VT5L2FSpdA%3D%3D; tg=0; _l_g_=Ug%3D%3D;\
        sg=%E5%A4%9C6f; _nk_=%5Cu7709%5Cu770B%5Cu6708%5Cu4E4B%5Cu591C;\
        cookie1=Vv6fkO6X3Dbd0%2BjR5Pm9%2FVMegu88LAEuGgMSjoFaFFg%3D;\
        enc=aBauooIlET%2FTz%2FO%2By206HZzzoZUzq%2BmM220DoSa8xXJAwE9%2FtIJe5hfuwu12e9GfpcG%2F9ZNzpm6JBo%2F2D%2BNsig%3D%3D; \
        mt=ci=110_1; hng=CN%7Czh-CN%7CCNY%7C156; swfstore=308335;\
        x=e%3D1%26p%3D*%26s%3D0%26c%3D0%26f%3D0%26g%3D0%26t%3D0%26__ll%3D-1%26_ato%3D0;\
        uc1=cookie14=UoTaHPGk7cSIQw%3D%3D&cookie15=V32FPkk%2Fw0dUvg%3D%3D;\
        whl=-1%260%260%261564908848429; JSESSIONID=9A789A993ECB09BAABEF6E4A29CC2510; \
        l=cBgxe_J4qUKhmO7bBOCg5uI8LO7OSIRA_uPRwCVXi_5Ba6Ls0d_Ok7JG-Fp6VjWd90TB4dG4psy9-etkiKy06Pt-g3fP.;\
        isg=BFtbb-bCgqTERv7QpzRjXQhf6r8FmG5bzZ8Il02YN9pxLHsO1QD_gnmuxswHC8cq'
        cookies = {}
        for line in coo.split(';'):#浏览器伪装
            name,value = line.strip().split('=',1)
            cookies[name] = value
        r = requests.get(url,cookies = cookies,headers = headers,timeout = 30)
        r.raise_for_status()
        r.encoding = r.apparent_encoding
        return r.text
    except:
        return ""

def parsePage(ilt,html):
    try:
        plt = re.findall(r'\"view_price\"\:\"[\d\.]*\"',html)
        tlt = re.findall(r'\"raw_title\":\".*?\"',html)
        for i in range(len(plt)):
            price = eval(plt[i].split(':')[1])#eval函数可以将获得的字符串的最外层的单引号或者双引号去掉
            title = eval(tlt[i].split(':')[1])
            ilt.append([price,title])
    except:
        print("")

def printGoodsList(ilt):
    tplt = "{:4}\t{:8}\t{:16}"
    print(tplt.format("序号","价格","商品名称"))
    count = 0
    for g in ilt:
        count = count + 1
        print(tplt.format(count,g[0],g[1]))

def main():
    goods = '书包'
    depth = 2
    start_url = 'https://s.taobao.com/search?q=' + goods
    infoList = []
    for i in range(depth):
        try:
            url = start_url + '&s=' + str(44*i)
            html = getHTMLTest(url)
            parsePage(infoList,html)
        except:
            continue
    printGoodsList(infoList)

main()

实例3：股票数据定向爬虫

功能描述

目标：获取上交所和深交所所有股票的名称和交易信息

输出：保存到文件中

技术路线：requests-bs4-re

候选数据网站的选择

新浪股票：https://finance.sina.com.cn/stock/

百度股票：https://gupiao.baidu.com/stock

选取原则：股票信息静态存在于HTML页面中，非js代码生成，没有Robots协议限制。

选取方法：浏览器F12，源代码查看等。

选取心态：不要纠结于某个网站，多找信息源尝试。

程序的结构设计

步骤1：从东方财富网获取股票列表

步骤2：根据股票列表逐个到百度股票获取个股信息

步骤3：将结果存储到文件

import requests
from bs4 import BeautifulSoup
import re
import traceback

#获得url对应的页面
def  getHTMLText(url,code = 'utf-8'):
    try:
        r = requests.get(url,timeout = 30)
        r.raise_for_status()
        #r.encoding  = r.apparent_encoding#编码识别的优化，手工的方式先获得编码的类型（apparent_encoding），然后直接赋给encoding
        r.encoding = code
        return r.text
    except:
        return ""

#获得股票的信息列表
def getStockList(lst,stockURL):
    html = getHTMLText(stockURL,'GB2312')
    soup = BeautifulSoup(html,'html.parser')
    a = soup.find_all('a')
    for i in a:
        try:
            href = i.attrs['href']
            lst.append(re.findall(r"[s][hz]\d{6}",href)[0])
        except:
            continue

#获得每一支个股的股票信息，并且把他存到某一个数据结构
def getStockInfo(lst,stockURL,fpath):
    count = 0
    for stock in lst:
        url = stockURL +stock + ".html"
        html = getHTMLText(url)
        try:
            if html == "":
                continue
            infoDict = {}
            soup = BeautifulSoup(html,'html.parser')
            stockInfo = soup.find('div',attrs={'class':'stock-bets'})
            name = stockInfo.find_all(attrs={'class':'bets-name'})[0]
            infoDict.update({'股票名称':name.text.split()[0]})
            keyList = stockInfo.find_all('dt')
            valueList = stockInfo.find_all('dd')
            for i in range(len(keyList)):
                key = keyList[i].text
                val = valueList[i].text
                infoDict[key] = val
            with open(fpath,'a',encoding='utf-8') as f:
                f.write(str(infoDict) + '\n')
                count = count + 1
                print("\r当前进度：{:.2f}%".format(count*100/len(lst)),end=' ')#增加动态的进度显示，
                #\r能够将我们打印的字符串的最后的光标提到当前这一行的头部，下一次再进行相关打印的时候，
                #打印的信息就会覆盖之前打印的内容，这样实现了一个不换行的、动态变化的信息展示
        except:
            count = count + 1
            print("\r当前进度：{:.2f}%".format(count*100/len(lst)),end=' ')
            traceback.print_exc()
            continue

def main():
    stock_list_url = 'http://quote.eastmoney.com/stock_list.html'
    stock_info_url = 'https://gupiao.baidu.com/stock/'
    output_file = 'D://BaiduStockInfo.txt'
    slist = []
    getStockList(slist,stock_list_url)
    getStockInfo(slist,stock_info_url,output_file)
    
main()

>>> r = requests.get('http://quote.eastmoney.com/stock_list.html',timeout = 30)
>>> r.apparent_encoding
'GB2312'
>>> r = requests.get('https://gupiao.baidu.com/stock/',timeout = 30)
>>> r.apparent_encoding
'utf-8'

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