Python3爬虫下载pdf（一）

"""
功能：下载指定url内的所有的pdf
语法：将含有pdf的url放到脚本后面执行就可以了
"""

from bs4 import BeautifulSoup as Soup
import requests
from sys import argv

try:
    ##用于获取命令行参数，argv[0]是脚本的名称
    root_url = argv[1]
except:
    print("please input url behind the script!!")
    exit()

##获得含有所有a标签的一个列表
def getTagA(root_url):
    res = requests.get(root_url)
    soup = Soup(res.text,'html.parser')
    temp = soup.find_all("a")
    return temp

##从所有a标签中找到含有pdf的，然后下载
def downPdf(root_url,list_a):
    number = 0
    ##如果网站url是以类似xx/index.php格式结尾，那么只取最后一个/之前的部分
    if not root_url.endswith("/"):     
        index = root_url.rfind("/")
        root_url = root_url[:index+1]
    for name in list_a:
        name02 = name.get("href")
        ##筛选出以.pdf结尾的a标签
        if name02.lower().endswith(".pdf"):
            pdf_name = name.string 
            number += 1
            print("Download the %d pdf immdiately!!!"%number,end='  ')
            print(pdf_name+'downing.....') 
             ##因为要下载的是二进制流文件，将strem参数置为True     
            response = requests.get(root_url+pdf_name,stream="TRUE")
            with open(pdf_name,'wb') as file:
                for data in response.iter_content():
                    file.write(data)

if __name__ == "__main__":
    downPdf(root_url,getTagA(root_url))